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7890 Series GC Troubleshooting

1. e Gas supply bulkhead fittings e Gas cylinder fitting e Regulator fittings e Traps e Shut off valves e T fittings Perform a pressure drop test 1 Turn off the GC 2 Set the regulator pressure to 415 kPa 60 psi Agilent 7890 Series Troubleshooting 127 7 128 Checking for Leaks Fully turn the regulator pressure adjustment knob counterclockwise to shut the valve Wait 10 min If there is a pressure loss greater than 7 kPa 1 psi there is a leak in the external connections Agilent 7890 Series Troubleshooting To Check for GC Leaks Agilent 7890 Series Troubleshooting Checking for Leaks 7 Check for leaks at these connections e Inlet septum septum head liner split vent trap split vent trap line and purge vent fittings e Column connections to inlets detectors valves splitters and unions e Fittings from the flow modules to the inlets detectors and valves e Column adapters e Agilent capillary flow fittings First use the GC s built in leak test to check for leaks at the inlet column fitting septum liner split vent trap line and so forth See To Perform an Inlet Leak Check Correct any leaks found using this test If the GC still shows symptoms of a leak check the other possible leak points If using Agi
2. A n oe ig ee er ate 3 Ss Oo o f g ll 8 8 A CA 5 Ss o I Le op i a e jo 93 4 GC Not Ready Symptoms Temperature Never Becomes Ready 94 To be considered ready a temperature must be at setpoint 1 C for 30 s If a temperature never becomes ready do the following e Check for a missing insulation cup on an inlet or detector e Check for a very large temperature difference between the oven and inlet or detector e Check for missing insulation around the inlet or detector e If using an inlet cryo cooling COC PTV or MMI Check cryo coolant level Check if operating limits have been exceeded If for example you are operating the GC in a hot room at a high oven temperature and a very low inlet temperature an inlet may not reach its desired temperature Agilent 7890 Series Troubleshooting GC Not Ready Symptoms 4 Cannot Set a Flow or Pressure Agilent 7890 Series Troubleshooting If you cannot set a flow or pressure using the split splitless MMI PTV VI or cool on column inlets do the following Check the column mode Check that a capillary column is configured to the correct inlet Check the configured column dimensions Check that the flow is turned on If you cannot set a flow or pressure using the purged packed inlet do the following Check the column mode
3. To Perform an Inlet Leak Check To Check for Leaks in a Split Splitless Inlet To Perform a PP Pressure Decay Leak Test To Check for Leaks in a Multimode Inlet To Perform a COC Pressure Decay Leak Test To Perform a PTV Pressure Decay Test To Perform a VI Pressure Decay Test e Check for sufficient carrier gas supply pressure The pressure delivered to the GC must be at least 40 kPa 10 psi greater than the maximum inlet pressure required at final oven temperature e Run replicates of known standards to verify the problem e Verify that you are using the correct liner type for the sample being injected See Selecting the correct inlet liner e Consider if this is the first run Has the GC stabilized e If using an FID or NPD and retention times increase drift check the jet for contamination or replace the jet To Replace an FID Jet To Check for a Plugged FID Jet To Maintain the NPD Collector Ceramic Insulators and Jet To Check for a Plugged NPD Jet 42 Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Peak Areas Not Repeatable Check the ALS syringe operation See the Troubleshooting section of the sampler user manual 7693A 7650A 7683B e Replace the syringe e Check for leaks in the inlet liner as applicable and column connection See Checking for Leaks e Check sample level in vials e Run replicates of known standards to verify the problem e Consider if this is the firs
4. 1 If recent changes were made in the system such as changing carrier or detector gases performing inlet or column maintenance or changing the column investigate the possibilities that contamination or leaks were introduced 2 If the problem has been chronic and is now acute enough to interfere with analysis suspect contamination column degradation or ultimately a bad ECD cell See also Display signal evaluation Sensitivity 63 3 64 Chromatographic Symptoms Display signal evaluation The first consideration is the signal value when the GC is in the idle state The idle signal level is a function of the type and quality of the carrier and detector gases as well as the flows and application It may be different for different situations but as a general rule the following values apply Table 4 Figure 3 shows typical uECD life cycle stages Table 4 uECD signal evaluation ECD signal Comments lt 200 uECD is healthy 200 to 400 Slightly elevated no cause for concern at this point Signal still in good range 400 to 1000 System showing signs of contamination from gases column or samples If the signal increases in response to increased oven temperature suspect the column 1000 to 2000 Suspect more severe contamination follow the troubleshooting guidelines gt 2000 If the following procedures do not work suspect the uECD cell It may take 24 hours for the uEC
5. 3 Chromatographic Symptoms FID Flame Goes Out During a Run and Attempts to Reignite 70 The following is an example chromatogram showing a flameout from a large solvent peak pA 9 co N o o ZS wo N 1 2 3 4 5 min After a flameout the GC will try to ignite the flame three times The GC tries to reignite whenever the detector output falls below the Lit offset setpoint regardless of whether or not the flame was extinguished In a very clean system the baseline output may be less than 2 pA If the FID flame goes out during a run do the following e See if an aromatic solvent peak or water extinguished the flame e Check for a plugged jet e Verify that the gas flow settings are correct Verify that Lit offset is set appropriately If the FID flame attempts to reignite but is already lit do the following e Verify that the FID Lit offset setting is appropriate for the run typically lt 2 0 pA e Check to see if an aromatic peak or water extinguished the flame e Check for a partially plugged jet Measure actual hydrogen air and makeup flows at the detector See To Measure a Detector Flow Replace the jet as needed Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 e Check that column is properly installed Reinstall it See To Install a Capillary Column in the FID Make sure the column is installed all the way to the tip and withdrawn 1 2 mm column id gt
6. FRONT INLET TRAP CHECK Inlet Pressure 5 471 psi lt Test Inlet ON to Start Test flow rate 400mL min Bag Warning if pressure check OFF Fault if pressure check OFF Last test results Tue Oct 20 16 07 2009 Test pressure OK 4 8 Reset the test results yes Figure 5 Example front inlet trap check display Example assumes a test has been previously run Scroll to see all lines of the display Scroll to Test flow rate and enter a flow rate A typical flow rate for this test is 400 mL min but you may find other values more appropriate for your setup Scroll to Test Inlet and press On Yes to start the test Wait while the pressure stabilizes When stable the Test Inlet line of the display changes to Test pressure OK x xx where x xx is the current pressure If the inlet cannot achieve the test setpoint check for a leak at the inlet split vent trap or split vent line or low supply gas pressure Note the resulting Inlet Pressure If the measured pressure exceeds any limits you have set up the GC will respond accordingly See To Check or Monitor Split Vent Line Backpressure Typical pressures for a clean split flow path are 1 2 psi 7 14 kPa at 400 mL min for a split liner 3 10 psi 21 69 kPa at 400 mL min for a splitless liner If the pressure for a splitless liner seems abnormally high for a clean system try reinstalling the liner 187 8 Troubleshooting Tasks If pressure on a clean
7. Long term noise drift eee Wander JPR DOO DA pr Short term noise Noisy baseline Agilent 7890 Series Troubleshooting A noisy baseline or high detector output can indicate leaks contamination or electrical problems Some noise is inevitable with any detector although high attenuations can mask it Since noise limits useful detector sensitivity it should be minimized e For all detectors check for leaks at the column fittings See Checking for Leaks e For the FID see To Isolate the Cause of FID Noise e For the TCD verify data collection at lt 5 Hz 57 3 58 Chromatographic Symptoms If noise appears suddenly on a previously clean baseline do the following Consider recent changes made to the system Bakeout the inlet See the following To Bakeout Contaminants from the Split Splitless Inlet To Bakeout Contaminants from the MMI Inlet To Bakeout Contaminants from the Purged Packed Inlet To Bakeout Contaminants from the COC Inlet To Bakeout Contaminants from the PTV Inlet To Bakeout Contaminants from the VI Inlet Bakeout can reduce septum bleed and other contaminants New septa may contribute noise from bleed of low molecular weight material If noise decreases when inlet temperature is lowered this is a likely cause Use only high quality septa and store them where they cannot become contaminated Verify the purity of carrier and detector gases If a tank was replaced recently and the old on
8. Set the equilibration time to 0 0 Verify that the flow settings are correct and appropriate See Flows temperatures and bead information If the process still fails there could be a large leak in the system This causes measured flow rates to be different from actual flow rates Thoroughly leak check the whole system especially the detector column adapter fitting See Checking for Leaks Check for fault messages Press Service Mode then go to Diagnostics gt Front detector or Back detector gt Detector signal You can also read the bead voltage Check the condition of the bead Replace if necessary Inspect the jet to see if it is clogged See To Check for a Plugged NPD Jet Measure the actual detector flows See To Measure a Detector Flow If the hydrogen or makeup flows are zero or much lower than the displayed flow suspect a plugged jet 37 2 ALS and Detector Symptoms FPD Temperature Will Not Become Ready 38 If the FPD emission block temperature will not become ready Check the oven temperature If the oven temperature is high over 325 C for a long time set the emission block temperature to its highest value 165 C Check the transfer line temperature If the transfer line is set to a very high temperature near 400 C set the emission block temperature to at least 150 C Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2 Blinking Not Ready Light Detector Ha
9. Check that the flow is turned on Check the inlet mode When using inlet flow control you can set only flow control modes for columns When using inlet pressure control you can set the column for both flow and pressure modes 95 4 GC Not Ready Symptoms A Gas Does Not Reach Setpoint Pressure or Flow 96 If an inlet does not reach its pressure setpoint it will shut down in an amount of time determined by the type of inlet Do the following Check for sufficient gas supply delivery pressure The pressure at the supply should be at least 10 psi greater than the desired setpoint Check for leaks See Checking for Leaks A large leak may be present somewhere in the system Use an electronic leak detector to find leaks then correct them Do not forget to check the column a broken column is a very large leak To troubleshoot a multimode or split splitless inlet see To Check for Leaks in a Multimode Inlet or To Check for Leaks in a Split Splitless Inlet If using gas saver be sure that the gas saver flow rate is high enough to maintain the highest column head pressure used during a run Check for an incorrectly installed column Check for a defective inlet or detector pressure sensor If you are using a split splitless inlet MMI inlet PTV inlet or volatiles interface Check the split ratio Increase the amount of split flow Agilent 7890 Series Troubleshooting GC NotReadySymptoms 4 A
10. area packing to allow complete sample vaporization Increase the inlet temperature and verify that the insulation cup is installed and contains insulation Check column cut and installation into the inlet See the topic for the SS MMI PTV and VI For any inlet operating in splitless mode with any detector 54 Check the inlet for leaks See Checking for Leaks Check liner type Use a liner optimized for splitless analysis deactivated large volume Verify that the oven starting temperature is less than the solvent boiling point Check column cut and installation into the inlet See the topic for the SS MMI PTV and VI Check that the solvent vapor volume does not exceed the liner capacity Check for appropriate purge delay time Liner volume column flow Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Sample Decomposition in Inlet Missing Peaks e Lower the inlet temperature e Check for air or water in the carrier gas verify gas purity and functionality of traps e Verify that the liner is appropriate for the sample being run e Perform complete inlet maintenance Replace all consumable parts and bake out the inlet e Install a deactivated liner if liner is used e Check for leaks at the septum liner and column fittings See Checking for Leaks e Install an Agilent Direct Connect liner e Use a pulsed pressure method for quicker sample transfer to column
11. assume that sufficient stabilization time has elapsed since the last change in operating conditions 59 3 60 Chromatographic Symptoms Baseline spiking If experiencing baseline wander check for leaks especially at the septum and at the column See Checking for Leaks If the leak is at the detector end of the column retention times are stable from run to run but sensitivity is reduced If it is at the inlet end sensitivity is reduced and retention times are increased Also consider whether the oven temperature program is sufficient Baseline drift is most often seen during temperature programming To correct baseline drift do the following e Verify that column compensation is used and the profile is current To compensate for bleed e Verify that the column is conditioned e Check column bleed while at operating temperature e Check the signal mode assigned to the column in the data system e Check the column compensation profile It may be too little upscale drift or too much downscale drift This cause of drift is minimized by thorough column conditioning Operating at a lower temperature reduces the drift but prolongs the analysis Use of a chromatographically equivalent column with a higher temperature limit is also possible There are two types of spiking on the baseline output cyclic and random Spiking will not normally be noticed on the display it will be noticed only on a plot or online
12. 100 um e Check for leaks at the detector column fitting See Checking for Leaks Agilent 7890 Series Troubleshooting 71 3 Chromatographic Symptoms FID Baseline Output Above 20 pA 72 Verify the purity of the carrier and detector gas supply See the Agilent GC GC MS and ALS Site Preparation Guide Inspect the column for column bleed Lower the oven temperature to ambient If the detector output drops significantly suspect a contaminated or bleeding column or contaminated carrier gas Confirm column bleed by turning off column flow with oven cool and checking the detector output Check the gas supply trap indicators dates and ensure that the traps are not expended Verify that the detector was reassembled properly after recent maintenance Inspect the detector for contamination Bake out the detector Check that the FID leakage current is lt 2 0 pA See To Measure FID Leakage Current Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 FID Baseline Output at Maximum 8 Million Agilent 7890 Series Troubleshooting If the FID output seems to be stuck at a very high value up to 8 million counts check for a shorted collector 1 Check if the interconnect spring has been bent Remove the collector assembly and visually inspect the spring Disassemble the collector assembly and visually check for rust buildup on any parts Replace parts as needed To avoid this problem
13. 70 kPa higher than the inlet pressure Wait 5 minutes for the pressure to equilibrate If pressure cannot be achieved there is either a large leak or the supply pressure is too low Set the Septum purge flow to 3 0 mL min Allow the inlet temperature to stabilize Temperature changes can invalidate the test Cap the septum purge fitting with the ECD TCD detector plug 155 7 Checking for Leaks Back inlet split vent Front inlet split vent 156 Back inlet purge vent O Front inlet o B O purge vent oo Front purge vent shown plugged 11 From the keypad press Service Mode Select Diagnostics gt Front or Back Inlet gt Pneumatics Control gt Septum Purge control 12 Scroll to the Constant duty cycle and enter 50 Wait 10 seconds 13 Press Front or Back Inlet Scroll to Pressure and press Off No 14 Quickly turn off the carrier gas supply at its source 15 Monitor the pressure for 10 minutes Use the timer by pressing Time and Enter A pressure drop of less than 1 0 psig 0 1 psi min or less 6 9 kPa or 0 69 kPa min is acceptable Agilent 7890 Series Troubleshooting Checking for Leaks 7 If the pressure drops much faster than the acceptable rate see To Correct Leaks in the Cool On Column Inlet Retest 16 After the inlet passes the test restore the GC to operating condition
14. Gas Exceeds Pressure Setpoint or Flow If a gas exceeds its pressure or flow setpoint do the following If using a split splitless inlet MMI inlet PTV inlet or volatiles interface Decrease the split ratio Replace the split vent filter See the procedure for the SS MMI PTV or VI Check the split vent trap line for contamination or an abnormal restriction Run the split vent restriction test in Agilent Instrument Utilities if available or from the GC front panel See To Check or Monitor Split Vent Line Backpressure To Run the Inlet Trap Check To Check a Split Vent Line for Contamination Verify that the correct liner is selected if liner is used See Selecting the correct MMI inlet liner or Selecting the correct SS inlet liner Verify the method pressure settings for the SS inlet are above the minimum viable settings available on the GC See Table 4 Check the gold seal for contamination for split splitless inlet See To Replace the Gold Seal on the Split Splitless Inlet For a split splitless inlet if using a liner that causes a restriction install a high flow gold seal If using an FID or NPD Check for a plugged jet See To Check for a Plugged FID Jet or To Check for a Plugged NPD Jet Valves Agilent 7890 Series Troubleshooting Check for a misaligned rotor Align the rotor 97 4 GC Not Ready Symptoms The Inlet Pressure or Flow Fluctuates 98 A fluctuation in inlet pres
15. Hydrogen and Makeup Gas Flows Much Less Than Setpoint e Check for a clogged or partially clogged jet A clogged jet creates backpressure Since the flow module uses pressure control the increased backpressure simulates proper flow The actual flow rate will drop but the GC remains functional See To Check for a Plugged FID Jet To Check for a Plugged NPD Jet e Check for a column fitting leak at the detector base e Replace the FID or NPD jet 104 Agilent 7890 Series Troubleshooting GC Not Ready Symptoms 4 NPD Adjust Offset Process Fails Agilent 7890 Series Troubleshooting Inspect the jet to see if it is clogged See To Check for a Plugged NPD Jet Measure the actual detector flows See To Measure a Detector Flow If the hydrogen or makeup flows are zero or much lower than the displayed flow suspect a plugged jet Check the condition of the bead Replace if necessary Verify that the flow settings are correct See Flows temperatures and bead information If the process still fails there could be a large leak in the system This causes measured flow rates to be different from actual flow rates Thoroughly leak check the whole system especially the detector column fitting See Checking for Leaks Set the equilibration time to 0 0 105 4 FPD Does Not Ignite 106 GC Not Ready Symptoms e Check that the FPD temperature is high enough for ignition gt 150 C e Check FPD flow ra
16. MSD can react to the shutdown event The GC cannot detect leaks in the detector gas streams For this reason it is vital that the column fittings of the FID NPD and any other detectors that use hydrogen always be connected to a column or have a cap or plug installed and that hydrogen streams be configured so that the GC is aware of them 114 Agilent 7890 Series Troubleshooting Shutdown Symptoms 5 To recover from a hydrogen shutdown state 1 Fix the cause of the shutdown Replace the inlet septum See the Maintenance manual Replace the inlet O ring See the Maintenance manual Check for broken column Check the supply pressure Make sure the gas supply meets the pressure recommendations listed in the Agilent GC GC MS and ALS Site Preparation Guide Check the system for leaks See Leak Check Tips 2 Power cycle the GC 3 After the GC powers back on press the key for the device that initiated the shutdown Scroll to the pneumatic parameter that is flashing Off then press On or Off For example if the front inlet ran out of carrier gas press Front Inlet scroll to the pressure or flow parameter then press On After a column shutdown you can turn on a detector gas flow even if the keyboard is locked by a data system Agilent 7890 Series Troubleshooting 115 5 Shutdown Symptoms 7890B MSD Shutdown If the 7890B receives a shutdown event from or loses communications with a connected 5977 MSD the GC
17. On After a column shutdown you can turn on a detector gas flow even if the keyboard is locked by a data system Agilent 7890 Series Troubleshooting 113 5 Shutdown Symptoms Hydrogen Shutdowns Hydrogen gas may be used as a carrier or as fuel for some detectors When mixed with air hydrogen can form explosive mixtures The GC monitors inlet and auxiliary gas streams If a stream is unable to reach its flow or pressure setpoint and if that stream is configured to use hydrogen the GC assumes that a leak exists It will warn you with a beep after 25 seconds and it will continue to beep in intervals After about 5 minutes the GC will shut down components to create a safe state The GC e Displays Hydrogen Safety Shutdown e Closes the carrier supply valve to the inlet and closes and turns off both pressure and flow controls When viewed these parameters will flash Off e Opens the split vent valves in the split splitless and PTV inlets e Turns off the oven heater and fan and opens the oven flaps e Turns off all heaters including any devices connected to the auxiliary heater controls such as valve box heaters and transfer line heaters When viewed these parameters will flash Off e Turns off the TCD filament e Turns off the FID or FPD ignitor and the air and fuel gas flows e Turns off the NPD bead and air and fuel gas flows e Sounds an alarm e 7890B Communicates with 5977 MSD if present so the
18. Remove any caps plugs Reinstall the column Restore the correct column configuration Load the operating method Agilent 7890 Series Troubleshooting 157 7 Checking for Leaks To Correct Leaks in the Cool On Column Inlet 158 If the inlet fails a pressure decay test check the following Check the caps plugs used in the test make sure each is correctly installed and tight If you performed the leak test after performing maintenance check for proper installation of the part s handled during the maintenance Check the tightness of the septum nut or cooling tower assembly See To change a septum nut or cooling tower and septum on a COC inlet Check the septum Replace if old or damaged Make sure the inlet temperature remained constant during the test If these items do not resolve the problem contact Agilent for service Agilent 7890 Series Troubleshooting Checking for Leaks 7 To Perform a PTV Pressure Decay Test See the procedure below If the test fails e Check the plugged column fitting and septum purge cap e Check the septum head Tighten if needed e Replace the septum if necessary e If using a septumless head tighten Rebuild as needed e Inspect and re install the liner if it is leaking e Replace the inlet adapter if it is leaking e Tighten the split vent trap if needed or install a new cartridge and O rings e Tighten the split vent line connection to the inlet To Perform a PT
19. Replace the syringe if necessary 7693A 7650A 7683 Check the viscosity of the sample against the viscosity parameter Reset the viscosity parameter if necessary Restart the sequence If the error occurs again obtain Agilent service Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2 Vial Mishandled by ALS 7693A Agilent 7890 Series Troubleshooting Refer to your sampler operating documentation for additional information When you find a mishandled sample vial do the following Check for folds or wrinkles in the crimp cap especially near the neck of the sample vial Use Agilent recommended sample vials The figure below shows the critical dimensions for sample vials and microvial inserts to be used with the 7693A ALS system These dimensions do not make up a complete set of specifications Body Diameter BD 11 7 0 2 Cap Diameter CD BD x 1 03 maximum All dimensions in millimeters co gt 6 25 0 25 3 7 min t A 33 5 1 5 32 40 5 Vial plus cap height 25 minimum body height S lt pp gt Maximum height of a capped vial Crimp cap sample vial Verify the transfer turret is installed if using a G4514A tray Check sample labels if applicable Check that they are the correct size Verify that the labels do not interfere with the gripper Vials are available with a write on spot for easy marking If you choose to make and apply your own
20. and Makeup Gas Flows Much Less Than Setpoint 104 Troubleshooting NPD Adjust Offset Process Fails 105 FPD Does Not Ignite 106 Valve Not Ready 108 External valves 108 Gas sampling valves 108 Multiposition valve 108 Blinking Not Ready Light Detector Hardware Fault TCD Filament Voltage 109 5 Shutdown Symptoms Column Shutdowns 112 Hydrogen Shutdowns 114 7890B MSD Shutdown 116 Clearing an MS Shutdown 116 After resolving an MS Shutdown 117 Thermal Shutdowns 118 6 GC Power On and Communication Symptoms GC Does NotTurnOn 120 PC Cannot Communicate with GC 121 GC Cannot Communicate with 5977 MSD 122 GC Does Not Recover After Firmware Update 123 GC Turns On Then Stops During Startup During Self Test 124 7 Checking for Leaks Leak Check Tips 126 To Check for External Leaks 127 To Check for GC Leaks 129 Leaks in Capillary Flow Fittings 130 To Perform an Inlet Leak Check 131 To set warning limits for a leak check 133 To disable a warning limit for the inlet leak check 133 To Check for Leaks in a Split Splitless Inlet 134 Cannot Reach Pressure Setpoint 134 Low Sensitivity or Poor Repeatability 135 To Perform a SS Pressure Decay Leak Test 136 To perform a SS inlet pressure decay test atthe GC keyboard 136 Troubleshooting Troubleshooting To Correct Leaks in the Split Splitless Inlet 141 To Check for Leaks in a Multimode Inlet 142 Cannot Reach Pressure Setpoint 142 Low Sensitivity or Poor Repeatability 143 To Perform a M
21. can invalidate the test 15 Cap the septum purge fitting with the ECD TCD detector plug Back inlet split Back inlet purge vent vent Front inlet split O vent n Front inlet Be O purge vent Ce 0 c Front purge vent shown plugged Agilent 7890 Series Troubleshooting 151 7 152 Checking for Leaks 16 1 18 19 2 21 22 From the keypad press Service Mode Select Diagnostics gt Front or Back Inlet gt Pneumatics Control gt Septum Purge control Scroll to the Constant duty cycle and enter 50 Wait 10 seconds Press Front or Back Inlet Scroll to Pressure and press Off No Quickly turn off the carrier gas supply at its source Monitor the pressure for 10 minutes Use the timer by pressing Time and Enter A pressure drop of less than 0 7 psig 0 07 psi min or less 4 8 kPa or 0 48 kPa min is acceptable If the pressure drops much faster than the acceptable rate see To Correct Leaks in the Packed Column Inlet Retest After the inlet passes the test restore the GC to operating condition Remove any caps plugs Reinstall the column Restore the correct column configuration Load the operating method Agilent 7890 Series Troubleshooting Checking for Leaks 7 To Correct Leaks in the Packed Column Inlet Agilent 7890 Series Troubleshooting If the inlet fails a pressure decay test check the fo
22. condition or to turn off the Service Due indicator 1 2 Press Service Mode scroll to Front inlet leak check or Back inlet leak check then press Enter Scroll to Reset the test results and press On Yes To disable a warning limit for the inlet leak check 1 2 Agilent 7890 Series Troubleshooting Press Service Mode scroll to Front inlet leak check or Back inlet leak check then press Enter Scroll to the warning limit then press Off No 133 7 Checking for Leaks To Check for Leaks in a Split Splitless Inlet 134 This procedures describes how to check for and fix leaks in the split splitless inlet Follow the procedures below based on the inlet s symptoms Cannot Reach Pressure Setpoint If the split splitless EPC inlet does not reach its pressure setpoint the GC will be Not Ready Pressing Status indicates the front or back inlet pressure is not ready The GC will shut down in approximately 5 5 minutes if the inlet cannot pressurize and control If you have recently performed maintenance first check for leaks on any fittings parts you handled 1 Verify sufficient gas supply pressure delivered to the GC see the GC GC MS and ALS Site Preparation Guide and verify no leaks in the gas supply see To Check for External Leaks The inlet requires 70 kPa 10 psi above the highest pressure used in the method 120 psi maximum for 0 100 psi inlet 170 psi maximum for 0 150 psi
23. flow rate See To Measure a Column Flow Hydrogen flow should be greater than the sum of the column flow and makeup flow If the analysis permits substitute nitrogen for helium as makeup 101 4 GC Not Ready Symptoms FID Ignitor Does Not Glow During Injection Sequence WARNING Keep body parts at a safe distance from the FID chimney while performing this task If using hydrogen the FID flame will not be visible 1 Remove the detector top cover 2 Turn the FID flame On 3 Observe the ignitor plug though the FID chimney The small hole should glow during ignition sequence If the test fails check for the following possible causes e The ignitor may be bad replace the ignitor See To Perform Maintenance on the FID Collector Assembly e Detector temperature is set to lt 150 C Agilent recommends operating the FID at gt 300 C e The ignitor is not making a good connection to the ground The ignitor must be tightly screwed into the FID castle assembly The three T 20 Torx screws that hold the collector assembly in place must be tight 102 Agilent 7890 Series Troubleshooting GC Not Ready Symptoms 4 e The brass knurled nut that holds the FID castle assembly in place must be tight Perform FID maintenance if these parts are corroded or oxidized T 20 Torx screws 3 Ignitor Knurled nut Agilent 7890 Series Troubleshooting 103 4 GC Not Ready Symptoms FID or NPD Measured
24. for split analysis e Method pressure parameter or resultant pressure from a flow setting is too low for the carrier gas type See Split Splitless inlet split mode minimum operating pressures or Multimode inlet split mode minimum operating pressures and the table below Table 5 Approximate minimum viable inlet pressures for inlet in split mode in psi split splitless multimode Helium and hydrogen carrier gases Split liners 5183 4647 19251 60540 Splitless liners 5062 3587 5181 8818 Nitrogen carrier gas Split liners 19251 60540 5183 4647 Splitless liners 5062 3587 5181 8818 Split vent flow mL min 50 100 100 200 2 5 3 5 4 0 5 5 3 0 4 0 4 0 6 0 200 400 4 5 8 0 400 600 6 0 11 0 Agilent 7890 Series Troubleshooting e Check for a plugged liner e Check for contamination or restriction in the split vent line See To Perform a SS Split Vent Restriction Test To Check or Monitor Split Vent Line Backpressure To Run the Inlet Trap Check To Check a Split Vent Line for Contamination e For the split splitless inlet replace gold seal See To Replace the Gold Seal on the Split Splitless Inlet 99 4 GC Not Ready Symptoms The Measured Column Flow Does Not Equal the Displayed Flow 100 If the actual column flow does not match the calculated flow displayed on the GC within 10 do the following Verify that the measured flows are corrected to 25 C and 1 atmosphere Verif
25. inch tube adapter between the detector exhaust and the flowmeter tubing Bois ee Flow Tracker 1000 8 Connect the flowmeter to the flowmeter adapter 9 Measure the actual flow rate of each gas one at a time Measuring NPD flows 1 Gather the following e NPD flowmeter adapter tool G1534 60640 180 Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 e Flow measuring insert 19301 60660 e Electronic flowmeter calibrated for the gas and flow rates of concern 2 Set the bead voltage to 0 0 V 3 Cool the NPD to 100 C WARNING Be careful The detector may be hot enough to cause burns If the detector is hot wear heat resistant gloves to protect your hands 4 Remove the bead and store it carefully until reinstallation 5 Insert the NPD flowmeter adapter tool into the NPD collector 6 Attach the flow measuring insert to the NPD flowmeter adapter tool Agilent 7890 Series Troubleshooting 181 8 Troubleshooting Tasks 7 Place the flowmeter tubing over the flow measuring insert to begin measuring flows 182 Agilent 7890 Series Troubleshooting Troubleshooting Tasks To Perform the GC Self Test 1 Turn the GC off 2 Wait 1 min then turn the GC back on If the main GC status screen appears the GC has passed the self test Agilent 789 B GC B xx xx xxx Power on successful Agilent 7890 Series Troubleshooting 183 8 Troubleshooting Tasks To Check or Monitor Sp
26. inlet maintenance Replace all consumable parts and bake out the inlet Perform column maintenance Bake out contaminants remove the contaminated length of column near the inlet and reverse and bake out the column as needed Verify that the column is installed properly Consider the filter type sulfur or phosphorus Check the system for leaks See Checking for Leaks Verify that the method settings are appropriate Check the flow rates Check the makeup gas type 71 3 Chromatographic Symptoms FPD Large Peak Width at Half Height If the FPD produces peaks that are abnormally wide at half the peak height do the following e Check the actual injection volume reduce if necessary e Verify that the liner is not reacting with the sample 78 Agilent 7890 Series Troubleshooting Chromatographic Symptoms FPD Baseline Output High gt 20 pA Agilent 7890 Series Troubleshooting Check the supply gas purity Check all trap indicators and dates Check the detector for contamination Check for light leaks at the photomultiplier tube PMT tighten the PMT if it is loose Perform complete inlet maintenance Replace all consumable parts and bake out the inlet Perform column maintenance Bake out contaminants as needed 3 79 3 Chromatographic Symptoms NPD Solvent Quenching 80 If the baseline does not recover after a solvent peak try the following e Turn hydrogen off on around the solvent pea
27. its pressure setpoint the GC will be Not Ready Pressing Status indicates the front or back inlet pressure is not ready The GC will shut down in approximately 5 5 minutes if the inlet cannot pressurize and control If you have recently performed maintenance first check for leaks on any fittings parts you handled 1 Verify sufficient gas supply pressure delivered to the GC see the GC GC MS and ALS Site Preparation Guide and verify no leaks in the gas supply see To Check for External Leaks The inlet requires 70 kPa 10 psi above the highest pressure used in the method 120 psi maximum for 0 100 psi inlet 170 psi maximum for 0 150 psi inlet Check the total flow setting Total flow must be high enough to maintain inlet pressure throughout the run Wide bore columns require higher flow rates Typically 50 mL min is sufficient To increase total flow Increase split ratio if in split mode Increase the purge flow for splitless mode Put your thumb or a septum over the split vent exhaust If the inlet pressure begins to rise to the setpoint call Agilent for service If the pressure remains low continue with the next step Perform the inlet leak check See To Perform an Inlet Leak Check The total flow provides an indication of the magnitude of the leak Monitor the total flow while checking tightening fittings Septum nut Column Split vent trap O rings Liner O rings Split vent line connection to
28. its state temperature flow pressure and so forth will continue to be ignored even if using this device in the analysis Agilent 7890 Series Troubleshooting To consider a device s readiness set Ignore Ready to False 205 oe Agilent Technologies To Use the Stopwatch In the stopwatch mode both the time to 0 1 second and reciprocal time to 0 01 min 1 are displayed Use the stopwatch when measuring flows with a bubble flowmeter 1 Press Time and scroll to the time line 2 Press Enter to start the stopwatch 3 Press Enter again to stop 4 Press Clear to set to zero You can access other functions while the stopwatch is running Press Time again to view the stopwatch display
29. labels Agilent Technologies recommends the positioning and maximum label thickness shown in the figure below 2 ALS and Detector Symptoms All dimensions in millimeters 13 2 maximum Text areas are optional A Text 3 6 min 26 6 max A ene Overlap mismatch ii 1 0 max 13 4 minimum 16 4 0 5 No label or tape l Yy Label skew 12 56 Maximum width measured at overlap e Check that the tray vial racks are clean and snapped into the tray base e Calibrate the system 20 Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2 Alignment Light on 7693A 7650A Injector Tower is On If the Align Mode light is on first verify that the turret is properly installed Then perform the alignment procedure as described in the 7693A Automatic Liquid Sampler Installation Operation and Maintenance manual or the 7650A Automatic Liquid Sampler Installation Operation and Maintenance manual Agilent 7890 Series Troubleshooting 21 2 ALS and Detector Symptoms Vial Mishandled by ALS 7683 Refer to your sampler operating documentation for additional information When you find a mishandled sample vial do the following e Check for folds or wrinkles in the crimp cap especially near the neck of the sample vial e Use Agilent recommended sample vials The distance from the vial bottom to the top of the neck should be approximately 28 4 mm The bottle neck diameter should be 8 2 0
30. or replacement The following procedure checks for causes of low sensitivity by frequency of occurrence For sensitivity loss associated with noise wander or drift also see Noisy Detector Including Wander Drift and Baseline Spikes 1 Check detector flow settings See Recommended starting conditions for new FID methods The general rule is 1 1 flow ratio of hydrogen to column makeup gas 2 Measure the actual detector flow rates See To Measure a Detector Flow If the actual hydrogen makeup and Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 capillary column flows are lower than the display the jet is becoming plugged See To Check for a Plugged FID Jet Replace the jet Check that column is properly installed Reinstall it See To Install a Capillary Column in the FID Make sure the column is installed all the way to the tip and withdrawn 1 2 mm column id gt 100 um Check inlet parameters that control venting such as split ratio and splitless purge delay time Make sure the sample is not being inadvertently vented Perform inlet maintenance replace all consumable parts and pressure test the inlet when completed See the maintenance manual and Checking for Leaks Perform complete FID maintenance Disassemble the FID and clean or replace all parts Refer to the following To Perform Maintenance on the FID Collector Assembly 69
31. peaks 75 3 Chromatographic Symptoms FPD Output Too High or Too Low e Verify that the correct filter is being used Do not use a phosphorus filter with sulfur optimized flows or a sulfur filter with phosphorus optimized flows e Check the position of the column as installed in the detector e Check the gas purity e Verify that the flows are optimized for the filter being used Monitor the FPD output The table below provides examples of detector output when the filter installed in the detector and the gas flows in use do not match Outputs Gas flows optimized With sulfur filter With phosphorus filter for Sulfur 30 to 50 10 to 12 low Phosphorus 240 to 250 high 30 to 50 Besides having a mismatch between the filter installed and a particular set of gas flows check the FPD signal output with the flame lit e If the output is 0 5 to 3 0 check that the flame is ON e If the output is 0 check if the electrometer is turned OFF or the signal cable is disconnected e If the output lt 30 the flame may be in the wrong position Check detector flows column flow and column position See the following To Measure a Column Flow To Measure a Detector Flow 76 Agilent 7890 Series Troubleshooting FPD Low Peak Areas Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Check the flow settings then measure the actual detector flows See To Measure a Detector Flow Perform complete
32. system is within these ranges but is near the operating pressure for the method consider a change in hardware or the method See also Cannot Maintain a Pressure as Low as the Setpoint on a Split Inlet 6 Press Off No to stop the test The most recent test results display at the bottom of the display Scroll down to see them To clear a Not Ready condition or Service Due indicator scroll to Reset the test results and press On Yes 188 Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 To Perform a SS Split Vent Restriction Test Agilent 7890 Series Troubleshooting Use the Agilent Instrument Utilities Split Vent Restriction Test to determine if there is an abnormal restriction in the split vent flow path Open the software select the GC and run the test for the inlet Alternately see To Run the Inlet Trap Check If the test fails e Consider whether the setup exceeds the minimum viable pressures obtainable by the GC See also Table 4 e Consider the liner used Agilent recommends a low pressure drop liner for split analyses part number 5183 4647 e Replace the split vent trap filter e Inspect and replace the gold seal If not using the low pressure drop liner consider installing a high flow gold seal 5182 9652 e Check for contamination in the split vent line See To Check a Split Vent Line for Contamination If the problem remains contact Agilent for service 189 Trouble
33. temperature by 50 C e Check for dead volume in the system Check for correct column installation at both ends If peak tailing decreases with retention time reduce dead volume in transfer line connections fused silica unions and so forth A column installed too high into a detector or inlet can create dead volume areas e Inspect any transfer lines for cold spots Cold spots cause tailing that usually increases with retention time NPD Peak Tailing For NPD do the following e Verify that you are using the correct bead for the sample being run If you are analyzing phosphorus install a black bead White beads can cause peak tailing when phosphorus is being analyzed e Verify that the correct jet is installed Use an extended jet e Replace the ceramic insulators Agilent 7890 Series Troubleshooting 53 3 Chromatographic Symptoms Peak Boiling Point or Molecular Weight Discrimination Poor If you have trouble with peak boiling point or molecular weight discrimination inlet discrimination do the following Check the inlet for contamination Clean and change the liner if necessary Replace all inlet consumable parts See the Maintenance manual Adjust the inlet temperature Run standards against a known method to determine expected performance For any inlet operating in split mode with any detector Check liner type Use a liner optimized for split analysis one that contains glass wool or other surface
34. that the 24 V supply to the pneumatics valves is actually less than 16 5 V All valves are disabled to prevent improper operation When full voltage is restored the GC becomes ready This Not Ready state could indicate a hardware problem in the external valve or in the GC analog and power board Gas sampling valves The GC is normally not ready whenever the inject time or load time has not elapsed It becomes ready when the specified load or inject time has passed Multiposition valve 108 A multiposition valve can cause the GC to be in a not ready state for one of the following reasons e The multiposition valve is not at the setpoint position The GC remains not ready until the valve reaches the setpoint e The BCD cable is missing or not plugged into the receptacle If the cable is missing the valve will never become ready e The BCD setpoint is incorrect for the valve BCD output polarity The valve will most likely shutdown with Illegal Position or Not Switching shutdown errors e If the valve is plugged or the sample is viscous the switching time may be too short for the valve to switch Increase the switching time Agilent 7890 Series Troubleshooting GC Not Ready Symptoms 4 Blinking Not Ready Light Detector Hardware Fault TCD Filament Voltage Agilent 7890 Series Troubleshooting If the TCD filament is open the Not Ready LED blinks and the GC will not become Ready 1 Press Status If the display
35. the VI from the sampler as described in To Prepare the VI for a Closed System Leak Check on page 168 After performing maintenance first check for leaks in externally accessible areas See To Check for External Leaks If a leak is known to exist check the externally accessible inlet fittings first especially any connection that has seen recent maintenance such as the column connection split vent line and so forth The pressure decay leak test described below requires removing the column and capping the inlet column fitting This test can cannot find the following types of leaks Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting Checking for Leaks 7 The test can find leaks at the The test cannot find leaks at the sampler connection column fitting pressure sensing line connection to gas supply bulkhead fittings to the the interface flow module split vent line connection to the tubing and connections in a transfer interface line connected to the inlet the connected sampler s entire sample flow path flow manifold split vent valve flow manifold septum purge valve split vent tubing and trap 1 oo N Q CI 10 11 12 Gather the following see Consumables and parts for the VI No hole ferrule 1 4 inch wrench Heat resistant gloves if the inlet is hot Long column nut ECD TCD Detector plug part no 5060 9055 Load the inlet maintenance method and wait for
36. trace Figure 1 Cyclic spiking Cyclic spiking can be caused by the following e An electric motor e Building heating cooling system Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Other electronic interferences in the lab Figure 2 Random spiking Spikes are isolated baseline disturbances usually appearing as sudden and large upscale movements If accompanied by noise resolve the noise problem first since spiking may disappear at the same time Agilent 7890 Series Troubleshooting Check for a contaminated detector In an extremely dirty FID particles of carbon or silicon dioxide may break away and fall into the detection zone For a packed column check that the packed column exit is properly sealed with glass wool This will cause packing particles to be blown into the detector A defective or missing glass wool plug at the exit of a packed column will do this This may happen with any detector but the flame detector is particularly susceptible because of the narrow bore of the jet Check packed column installation The bottom of the jet or the end of a transfer tube extends into the end of the column If it touches a glass wool plug spikes are produced Check for the correct jet See the following Selecting an FID jet To replace an FID jet Selecting an NPD jet To Maintain the NPD Collector Ceramic Insulators and Jet 61 62 3 Chromatographic Symptoms Check that the detector tempe
37. troubleshooting for 7890 Series GCs in general when describing GC keyboard usage and firmware features this manual assumes a 7890B GC using firmware B 02 01 Features that are specific to one GC model only 7890A or 7890B are noted How to troubleshoot using this manual The Status key Use the following steps as a general approach to troubleshooting 1 Observe the symptoms of the problem 2 Look up the symptoms in this manual using the Table of Contents or the Search tool Review the list of possible causes of the symptom 3 Check each possible cause or perform a test that narrows the list of possible causes until the symptom is resolved Be sure to also use the Status and Info keys on the GC keypad while using this troubleshooting information These keys will display additional useful information related to the status of the GC and its components Agilent 7890 Series Troubleshooting Error conditions Agilent 7890 Series Troubleshooting Concepts and General Tasks If a problem occurs a status message appears If the message indicates broken hardware more information may be available Press the applicable component key for example Front Det Oven or Front Inlet 1 1 Concepts and General Tasks 7890B 5977 GC MSD Systems When used with a 5977 MSD the 7890B GC and MSD closely interact with each other In addition to simply sending start run commands and general status information ready or not rea
38. 1 2 days Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Low Peak Area or Height Low Sensitivity Agilent 7890 Series Troubleshooting If using an inlet in split mode check the split ratio Check for leaks See Checking for Leaks To troubleshoot small leaks in a multimode or split splitless inlet see To Check for Leaks in a Split Splitless Inlet or To Check for Leaks in a Multimode Inlet Check the inlet for contamination See Contamination or Carryover Check each column and verify that it was cut and installed properly at each end Verify that the column type is correct Perform column maintenance Bake out contaminants remove the contaminated length of column near the inlet and reverse and bake out the column as needed Verify that the liner type is appropriate for the sample Verify that the detector flow settings are correct Measure the actual detector flows If an actual flow does not match the GC display check for contamination and restrictions for example a plugged jet See the following To Measure a Detector Flow To Check for a Plugged FID Jet To Check for a Plugged NPD Jet Check the supply gas purity Check all trap indicators and dates Verify that the method parameters are correct Some samples change with heat or ultraviolet light Check sample stability Check configured syringe size Some syringe sizes are specified at half capacity If the maximum syringe vo
39. 2 mm The sampler injector and the tray use clear or amber glass sample vials with crimp caps or Target DP screw cap vials Use amber glass vials for light sensitive samples Refer to your Agilent catalog for consumables and supplies for acceptable vial types Incompatible sample vials cause tray and turret errors The figure below shows the critical dimensions for sample vials and microvial inserts to be used with the sampler These dimensions do not make up a complete set of specifications 5 minimum o 6 25 0 25 34 5 maximum re 11 7 0 2 Microvial insert Crimp cap sample vial Maximum height of a capped vial All dimensions in millimeters 22 Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2 Verify the transfer turret is installed if using a tray and G2913A injector Check sample labels if applicable Check that they are the correct size Verify that the labels do not interfere with the gripper Vials are available with a write on spot for easy marking If you choose to make and apply your own labels Agilent Technologies recommends the positioning and maximum label thickness shown in the figure below All dimensions in millimeters A No label or tape P 0 44 A a Bar code 3 6 min 5 6 0 6 25410 i No label or tape Y y Check that the tray vial racks are cle
40. Bends During Injection into Inlet 25 FID Fails Leakage Current Test 26 Possible causes 26 Procedure 26 NPD Fails Leakage Current Test 27 FID Fails Baseline Test 28 To Resolve Low Sensitivity with an FID 29 FID Does Not Ignite 30 FID Ignitor Does Not Glow During Ignition Sequence 31 Corrosion in FID Collector and Ignitor Glow Plug 33 Troubleshooting FPD Does Not Ignite 34 NPD Adjust Offset Process Fails 36 NPD Bead Will Not Ignite 37 FPD Temperature Will Not Become Ready 38 Blinking Not Ready Light Detector Hardware Fault TCD Filament Voltage 39 Shutdown Defective Device 40 3 Chromatographic Symptoms Retention Times Not Repeatable 42 Peak Areas Not Repeatable 43 Contamination or Carryover 44 Isolate the source 44 Check possible causes all inlet and detector combinations 44 Larger Peaks Than Expected 47 Peaks Not Displayed No Peaks 48 Baseline Rise During Oven Temperature Program 50 Poor Peak Resolution 51 Peak Tailing 52 NPD Peak Tailing 53 Peak Boiling Point or Molecular Weight Discrimination Poor 54 For any inlet operating in split mode with any detector 54 For any inlet operating in splitless mode with any detector 54 Sample Decomposition in Inlet Missing Peaks 55 Peak Fronting 56 Noisy Detector Including Wander Drift and Baseline Spikes 57 Noisy baseline 5 7 Baseline wander and drift 59 Baseline spiking 60 Microcell Electron Capture Detector uECD Noise and Sensitivity 63 Display signal
41. D baseline to completely stabilize especially if you are starting with a cold system and want to assure high sensitivity operation For the most accurate results run the detector at normal operating conditions for as long as possible at least 2 hours and up to 24 hours before running the frequency test If you will be injecting into an unused inlet you must use low bleed septa Make sure to condition new septa before use in an inlet for several hours with 1 to 5 mL min carrier flow Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Typical ECD Life Cycle Stages Stage 1 New cell Background 100 Hz Cell meets Agilent signal to noise S N standard Stage 2 6 months 1 year Background 180 Hz Increased response Stage 3 1 2 years Background 350 Hz More response increasing noise lower S N Stage 4 2 4 years Background gt 500 Hz Noisy baseline negative peaks Thermal cleaning required Stage 5 4 10 years Background gt 1000 Hz Huge response Very noisy cell contaminated Requires cell exchange Figure 3 Typical ECD life cycle Sensitivity If the ECD is in the good signal range and sensitivity is the issue the problems quite likely may be in the inlet or column Consider the following issues 1 If using an inlet with split and splitless modes verify that the mode has not changed and that the split valve is functioning This can be done by verifying that there is a correspond
42. Decay Test To Perform a PP Pressure Decay Leak Test To Perform a PTV Pressure Decay Test To Perform a VI Pressure Decay Test Agilent 7890 Series Troubleshooting Checking for Leaks 7 To set warning limits for a leak check The GC provides two alerts related to the inlet leak check Warning if pressure check If the measured pressure exceeds the limit turn on the Service Due indicator Fault if pressure check If the measured pressure exceeds the limit make the GC Not Ready You can determine reasonable inlet leak check results then set the GC to either go Not Ready or set the Service Due indicator if the leak check fails To set one or both limits 1 When the inlet is considered leak free run the inlet leak check Assume the inlet is leak free if the TotalFlow and Col readings are very close and you are satisfied with the GC s chromatographic results Note the TotalFlow result Scroll to Warning if pressure check or Fault if pressure check Enter a limit using the keypad then press Enter Select a flow rate that is higher than the acceptable TotalFlow reading Ideally enter a value that corresponds to known chromatographic problems The warning and fault limits can be different for example a warning at a lower limit and a fault at a higher one If desired repeat for Fault if pressure check The test is now set up Periodically rerun the test When the test fails fix any leaks To clear a Not Ready
43. Diagnostics gt Front or Back Inlet gt Pneumatics Control gt Septum Purge control Scroll to the Constant duty cycle and enter 50 Wait 10 seconds Press Front Inlet or Back Inlet Scroll to Pressure and press Off No Quickly turn off the carrier gas supply at its source Monitor the pressure for 10 minutes Use the timer by pressing Time and Enter For GCs with no device installed in the carrier flow path A pressure drop of less than 0 5 psig 0 05 psi min or less 3 4 kPa or 0 34 kPa min is acceptable If the pressure drops much faster than the acceptable rate see To Correct Leaks in the Split Splitless Inlet Retest For a GC with a 7697A Headspace Sampler A pressure drop of less than 1 7 psig 0 17 psi min or less 11 7 kPa or 1 17 kPa min is acceptable If the 7697A passes all its leak tests restriction pressure decay and cross port and if the GC inlet pressure decay test passes without the 7697A installed check the 7697A carrier flow path See the Headspace Sampler documentation For a GC with a G1888 Headspace Sampler A pressure drop of less than 2 psig in 5 minutes 0 4 psi min or less 13 8 kPa or 2 76 kPa min is acceptable when using a 1 cc sample loop For all GCs Note that liner size impacts pressure drop An inlet with a smaller volume liner does not tolerate as large a leak rate as an inlet with a larger volume liner 139 7 Checking for Leaks 21 After the inlet pass
44. EO 101150234 5 Agilent 7890 Series Gas Chromatograph Troubleshooting Agg Agilent Technologies Notices Agilent Technologies Inc 2013 No part of this manual may be reproduced in any form or by any means including electronic storage and retrieval or translation into a foreign language without prior agreement and written consent from Agilent Technologies Inc as governed by United States and international copyright laws Manual Part Number 63430 90053 Edition First edition January 2013 Printed in USA Agilent Technologies Inc 2850 Centerville Road Wilmington DE 19808 1610 USA BCR 18 ERAS LSS THAR St RX RER 412 5 Ai 800 820 3278 Warranty The material contained in this document is provided as is and is subject to being changed without notice in future editions Further to the maximum extent permitted by applicable law Agilent disclaims all warranties either express or implied with regard to this manual and any information contained herein including but not limited to the implied warranties of merchantability and fitness for a particular purpose Agilent shall not be liable for errors or for incidental or consequential damages in connection with the furnishing use or performance of this document or of any information contained herein Should Agilent and the user have a separate written agreement with warranty terms covering the material in this document that conflict with these te
45. Front or Back Inlet gt Pneumatics Control gt Septum Purge control Scroll to the Constant duty cycle and enter 50 Wait 10 seconds Press Front or Back Inlet Scroll to Pressure and press Off No Quickly turn off the carrier gas supply at its source Monitor the pressure for 10 minutes Use the timer by pressing Time and Enter A pressure drop of less than 0 5 psig 0 05 psi min or less 3 4 kPa or 0 34 kPa min is acceptable If the pressure drops much faster than the acceptable rate see To Correct Leaks in the PTV Inlet Retest Note that liner size impacts pressure drop An inlet with a smaller volume liner does not tolerate as large a leak rate as an inlet with a larger volume liner After the inlet passes the test restore the GC to operating condition Remove any caps plugs Reinstall the column Restore the correct column configuration Load the operating method Agilent 7890 Series Troubleshooting Checking for Leaks 7 To Correct Leaks in the PTV Inlet If the inlet fails a pressure decay test check the following Check the caps plugs used in the test make sure each is correctly installed and tight If you performed the leak test after performing maintenance check for proper installation of the part s handled during the maintenance If using a septum head check the tightness of the septum nut See To change the septum on the PTV inlet If using a septum head check the septum Repla
46. Leak Test If the test passes consider the inlet leak free and check other possible causes for the low sensitivity or poor repeatability 2 If the pressure decay test fails perform the inlet leak check See To Perform an Inlet Leak Check Monitor the total flow while checking tightening fittings Septum nut Column Split vent trap Liner O ring Gold seal Split vent line connection to the inlet body Flow block fittings on the flow manifold 3 If the inlet prep run leak check did not resolve the problem the leak may be too small to detect using that test Use an electronic leak detector to check the fittings connections If these checks do not resolve the problem contact Agilent for service Agilent 7890 Series Troubleshooting 135 7 Checking for Leaks To Perform a SS Pressure Decay Leak Test 136 Use the Agilent Instrument Utilities Split Splitless Inlet Pressure Decay Test to determine if the inlet is leaking Open the software select the GC and run the test for the inlet See To Perform an Inlet Leak Check and To Perform a SS Split Vent Restriction Test If the Instrument Utilities software is not available see the procedure below If the test fails e See To Check for Leaks in a Split Splitless Inlet e Check the plugged column fitting and septum purge cap To perform a SS inlet pressure decay test at the GC keyboard The pressure decay test checks for leaks from the inlet flow module u
47. Leaks Prepare and use a column compensation profile Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Poor Peak Resolution e Set column flow to optimum linear velocity e Install and use deactivated consumable parts in the inlet for example a liner e Perform column maintenance Bake out contaminants remove the contaminated length of column near the inlet and reverse and bake out the column as needed e Check column installation at both ends e Select a higher resolution column Agilent 7890 Series Troubleshooting 51 3 Peak Tailing 52 Chromatographic Symptoms The figure below shows an example of tailing peaks When troubleshooting tailing peaks consider e Which peaks are tailing e Are the tailing peaks active compounds all compounds or are there trends such as early eluters or late eluters Check the column for severe contamination If using a capillary column remove 1 2 to 1 meter from the front of the column For bonded and cross linked phases solvent rinse the column Check for inlet contamination Tailing will sometimes increase with compound retention Clean the inlet and replace contaminated inlet parts See the 7890 Series Maintenance manual Consider the column stationary phase active column This only affects active compounds An active column usually produces tailing that increases with retention time Cut off 1 mete
48. MI Pressure Decay Test 144 To Perform a Multimode Inlet Pressure Decay Test 144 To Correct Leaks in the Multimode Inlet 148 To Perform a PP Pressure Decay Leak Test 149 To Perform a PP Inlet Pressure Decay Test 149 To Correct Leaks in the Packed Column Inlet 153 To Perform a COC Pressure Decay Leak Test 154 To Performa COC Pressure Decay Test 154 To Correct Leaks in the Cool On Column Inlet 158 To Perform a PTV Pressure Decay Test 159 To Perform a PTV Pressure Decay Test 159 To Correct Leaks inthe PTV Inlet 163 To Perform a VI Pressure Decay Test 164 To Perform a VI Pressure Decay Test 164 To Prepare the VI for a Closed System Leak Check 168 To Correct Leaks in the Volatiles Interface 169 8 Troubleshooting Tasks To Measure a Column Flow 172 Measuring FID TCD uECD and FPD column flow 172 Measuring NPD column flow 173 To Measure a Split Vent or Septum Purge Flow 176 To Measure a Detector Flow 178 Measuring FID TCD uECD and FPD flows 178 Measuring NPD flows 180 To Perform the GC Self Test 183 To Check or Monitor Split Vent Line Backpressure 184 To set a warning limit for the inlet trap check 185 To disable a warning limit for the inlet trap check 186 To Run the Inlet Trap Check 187 To Perform a SS Split Vent Restriction Test 189 To Adjust the FID Lit Offset 190 To Verify That the FID Flame Is Lit 191 To Verify FID Ignitor Function During Ignition Sequence 192 To Measure FID Leakage Current 193 To Measu
49. OTE connector and whether they are flashing or constant For older GCs look through the slots in the GC right side panel where shown below Contact Agilent for service and provide the display information to the Agilent support personnel See also Information to Obtain Before Calling Agilent for Service Older GC LEDs visible through side panel Agilent 7890 Series Troubleshooting Agilent 7890 Series Gas Chromatograph Troubleshooting 7 Checking for Leaks Leak Check Tips 126 To Check for External Leaks 127 To Check for GC Leaks 129 Leaks in Capillary Flow Fittings 130 To Perform an Inlet Leak Check 131 To Check for Leaks in a Split Splitless Inlet 134 To Perform a SS Pressure Decay Leak Test 136 To Correct Leaks in the Split Splitless Inlet 141 To Check for Leaks in a Multimode Inlet 142 To Perform a MMI Pressure Decay Test 144 To Correct Leaks in the Multimode Inlet 148 To Perform a PP Pressure Decay Leak Test 149 To Correct Leaks in the Packed Column Inlet 153 To Perform a COC Pressure Decay Leak Test 154 To Correct Leaks in the Cool On Column Inlet 158 To Perform a PTV Pressure Decay Test 159 To Correct Leaks inthe PTV Inlet 163 To Perform a VI Pressure Decay Test 164 To Prepare the VI for a Closed System Leak Check 168 To Correct Leaks in the Volatiles Interface 169 Phe Agilent Technologies 125 7 Checking for Leaks Leak Check Tips When checking for leaks consider the syst
50. Series Troubleshooting Chromatographic Symptoms 3 NPD Low Selectivity High hydrocarbon response relative to nitrogen or phosphorus e Verify that the hydrogen flow is correct lt 3 mL min e Inspect the bead it may be defective or expended e Verify correct bead voltage e Replace the collector and insulators Agilent 7890 Series Troubleshooting 85 3 Chromatographic Symptoms Negative Peaks Seen with TCD 86 Verify that the correct gas type is being used Check for a leak in the system especially at the detector column fitting See Checking for Leaks Consider thermal conductivity of analytes relative to carrier Check the flow settings then measure the actual detector flows See To Measure a Detector Flow Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 TCD Baseline Has Dampened Sinusoidal Noise Trailing Peaks Ringing Baseline TCD1 A RINGINGICT_50001 D 25 uv 120 100 Q w o o 3 9 3 92 3 94 3 96 8 N 1 2 3 Wrong data rate is selected in the data system For TCD the data rate should be lt 5 Hz Agilent 7890 Series Troubleshooting 87 3 Chromatographic Symptoms TCD Peaks Have Negative Dip on Tail e Check for leaks at the detector column adapter fitting See Checking for Leaks e Upgrade the detector to a passivated filament 88 Agilent 7890 Series Troubleshooting Agilent 7890 Series Gas Chromatograph Troublesho
51. V Pressure Decay Test The pressure decay test checks for leaks from the inlet flow module up to the column fitting After performing maintenance first check for leaks in externally accessible areas See To Check for External Leaks If a leak is known to exist check the externally accessible inlet fittings first especially any connection that has seen recent maintenance such as the septum nut column adapter column connection and so forth The pressure decay leak test described below requires removing the column and capping the inlet column fitting This test can cannot find the following types of leaks Agilent 7890 Series Troubleshooting 159 7 160 Checking for Leaks The test can find leaks at the The test cannot find leaks at the septum column fitting septum nut gas supply bulkhead fittings to the flow module liner O ring seal tubing and connections in a transfer line connected to the inlet gold seal washer and reducing nut inlet body flow manifold split vent valve flow manifold septum purge valve split vent tubing and trap septum purge tubing seals within the tubing between the inlet flow module and the inlet body 1 Gather the following see Consumables and parts for the PTV inlet No hole ferrule 1 4 inch wrench Heat resistant gloves if the inlet is hot Column nut New septum New Graphpak 3D ferrule and liner ECD TCD Detector plug part no 5060 9055 2 Load the inlet mainten
52. ackground signal Reduce the bead voltage to zero to establish a reference level and then look for a sudden sharp increase in output as the bead voltage increases which indicates that ignition occurred If 4 V are being supplied to the bead but it is not igniting the bead is probably burned out Replace the bead e Replace the insulators collector e Check for liquid phase contamination polar phases Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 NPD Baseline Output gt 8 million e The collector is shorted to the detector housing Disassemble the collector and insulators and reinstall Agilent 7890 Series Troubleshooting 83 3 Chromatographic Symptoms NPD Adjust Offset Process Not Functioning Properly 84 Inspect the jet to see if it is clogged See To Check for a Plugged NPD Jet Measure the actual detector flows See To Measure a Detector Flow If the hydrogen or makeup flows are zero or much lower than the displayed flow suspect a plugged jet Check the condition of the bead Replace if necessary Verify that the flow settings are correct See Flows temperatures and bead information If the process still fails there could be a large leak in the system This causes measured flow rates to be different from actual flow rates Thoroughly leak check the whole system especially the detector column fitting See Checking for Leaks Set the equilibration time to 0 0 Agilent 7890
53. an and snapped into the tray base If the tray cannot deliver or retrieve vials from a bar code reader 1 Press Config Scroll to and select Sample tray Scroll to Grip offset and press Mode Type Aa WwW N Scroll to the desired adjustment Up Default or Down and press Enter If the sample vial touches the side of the turret hole as the vial is raised or lowered adjust the turret rotation For 7683B adjust the gripper height as follows 1 Press Config Scroll to and select Sample tray Scroll to Front injector offset and press Mode Type Aa O N Scroll to the desired adjustment Clock Counterclock or Default and press Enter 23 2 ALS and Detector Symptoms Alignment Light on 7683B Injector Tower is On Refer to the 7683B Automatic Liquid Sampler Installation Operation and Maintenance manual for additional information When the Align Mode light is on the injector will not operate until the following procedure is performed 1 24 When the injector is not operating open the injector tower door Slide the syringe carriage up until it stops Remove the syringe Carefully remove the needle support assembly from the injector Use a pen to press the recessed alignment button located above the indicator lights then close the door The injector will then go through the following steps a The turret rotates to verify that the needle support assembly was removed then rotates to deter
54. an enclosed space for example a flow meter Purge flowmeters with inert gas as needed Always measure gases individually Always turn off detectors to prevent flame bead autoignition CAUTION 1 Gather the following Appropriate flowmeter adapter tube can be found in the GC ship kit Electronic flowmeter calibrated for the gas and flow rates of concern To avoid damaging the column cool the oven before turning off the column flow 2 Set the oven temperature to ambient 35 C 3 Turn off the column flow and pressure 4 Shut off all detector gases Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 Turn off where applicable the FID flame FPD flame and TCD filament Cool the detector Connect the appropriate adapter to the detector exhaust Flowmeter tube diameters vary by model modify the adapter to the flowmeter tubing as needed A rubber adapter tube attaches directly to a uECD or TCD exhaust vent A separate adapter 19301 60660 is supplied for the FID Insert the adapter into the detector exhaust vent as far as possible You will feel resistance as the adapter O ring is forced into the detector exhaust vent Twist and push the adapter during insertion to ensure a good seal 179 8 Troubleshooting Tasks For the FPD remove the plastic tubing from the FPD exhaust and connect the flowmeter directly to the FPD vent tube If necessary use a 1 4
55. ance method and wait for the GC to become ready 3 Remove the column if installed 4 Plug the column fitting with a column nut and a no hole ferrule 5 If using the septum head and the quality of the septum or Microseal and GRAPHPACK 3D ferrule on the glass liner are unknown replace them now See To change the septum on the PTV inlet and To change the liner on the PTV inlet 6 Set the inlet to Split Mode 7 Configure the column as 0 length Agilent 7890 Series Troubleshooting Back inlet split oso co Checking for Leaks 7 Set the inlet temperature to 100 C Set the Total flow to 60 mL min Enter a pressure setpoint of 25 psi 172 kPa Make sure that the pressure supplied to the GC is at least 10 psi 70 kPa higher than the inlet pressure If pressure cannot be achieved there is either a large leak or the supply pressure is too low Set the Septum purge flow to 3 0 mL min Allow the inlet temperature to stabilize Temperature changes can invalidate the test Cap the septum purge fitting with the ECD TCD detector plug Back inlet purge vent vent Front inlet split O vent co Front inlet Be O purge vent Agilent 7890 Series Troubleshooting 161 7 Checking for Leaks gt A Front purge vent shown plugged E eal 15 1 ao 17 18 1 o 20 162 From the keypad press Service Mode Select Diagnostics gt
56. artificially low signal in the GC incorrectly indicating that the flame has gone out As a result the run aborts and the GC tries to relight an already lit flame You can verify that the flame is lit by holding a cold shiny surface such as a mirror or a wrench over the exit tube Condensation on the surface indicates that the flame is lit Reset the Lit offset to 2 0 74 Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 FPD Quenching Repeatability Agilent 7890 Series Troubleshooting Hydrocarbon quenching occurs when a high concentration of carbon dioxide from a hydrocarbon peak is in the flame at the same time as the sulfur species Part of the light emitted by the sulfur species is absorbed by some CO2 species Self quenching occurs at high concentrations of the heteroatom species Some other ground state inactivated species reabsorbs the emitted photon preventing it from reaching the PMT To resolve hydrocarbon quenching e The column should provide good separation of the compounds those that contain sulfur or phosphorus as well as those that do not but may absorb light e Optimize the chromatographic separation such that hydrocarbon peaks are resolved from sulfur or phosphorus peaks 1 Run the analysis first on a FID in order to see all the peaks the FPD ignores hydrocarbons 2 Run the analysis on the FPD 3 Modify the method so that the peak of interest is separate from the rest of the
57. ased on history of a given detector or comparison with another detector in the lab For proper diagnosis of noise it is important to evaluate the detector noise under documented conditions against a known standard Find more detailed information about noise in Noisy Detector Including Wander Drift and Baseline Spikes Before troubleshooting the detector perform a noise test using your Agilent data system If the detector fails the noise test then troubleshoot the cause as described below To isolate the cause of FID noise 1 If the noise test fails remove the column and re evaluate detector noise with the FID capped and re ignited using only H2 air and makeup detector gases If it passes suspect contaminated column carrier gas 2 If the noise failed with no column installed repeat the noise test with only H2 and air set makeup flow to Off If it passes suspect contaminated makeup gas 3 If the noise test still fails see To Measure FID Leakage Current If the leakage test fails replace or clean the collector and PTFE insulators the interconnect with spring and or the entire FID electrometer assembly If the leakage test fails replace or clean the collector and PTFE insulators the interconnect with spring and or the entire FID electrometer assembly 4 If the leakage current test is OK suspect a contaminated jet or contaminated H2 or Air detector gas supplies gases tubing traps especially if the background of the
58. ccessible areas See To Check for External Leaks If a leak is known to exist check the externally accessible inlet fittings first especially any connection that has seen recent maintenance such as the septum nut column adapter column connection and so forth See To Check for External Leaks The pressure decay leak test described below requires removing the column and capping the inlet column fitting This test can cannot find the following types of leaks 154 Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting Checking for Leaks 7 The test can find leaks at the The test cannot find leaks at the septum column fitting septum nut or cooling tower gas supply bulkhead fittings to the flow module seals within the tubing between the inlet flow module and the inlet body inlet body 1 10 Gather the following see Consumables and parts for the COC inlet No hole ferrule 1 4 inch wrench Heat resistant gloves if the inlet is hot Column nut New septum ECD TCD Detector plug part no 5060 9055 Load the inlet maintenance method and wait for the GC to become ready Remove the column if installed Plug the column fitting with a column nut and no hole ferrule Remove the old septum and replace it with a new one See To change a septum on the COC inlet Enter a pressure setpoint of 25 psi 172 kPa Make sure that the pressure supplied to the GC is at least 10 psi
59. ce if old or damaged Check that the septumless or septum head assembly is installed tightly Replace the liner and Graphpak 3D ferrule See To change the liner on the PTV inlet Check the Graphpak adapter seal against the inlet body Replace the silver seal and reinstall the adapter if needed See To replace the inlet adapter for the PTV inlet If using the septumless head check for leaks around the guide cap Replace the PTFE ferrule in the guide cap See To replace the PTFE ferrule on a PTV inlet Check for leaks at the split vent trap Tighten as necessary Replace the split vent trap filter and O rings See To replace the filter in the PTV inlet split vent line Make sure the inlet temperature remained constant during the test If these items not resolve the problem contact Agilent for service Agilent 7890 Series Troubleshooting 163 7 Checking for Leaks To Perform a VI Pressure Decay Test 164 See the procedure below If the test fails e Check the plugged column fitting and septum purge cap e Tighten the pneumatic connections to the volatiles interface Install new seals as needed e Tighten the split vent trap if needed or install a new cartridge and O rings To Perform a VI Pressure Decay Test The pressure decay test checks for leaks from the inlet flow module up to the column fitting Initially test the VI with a sampling system installed If the system fails the leak test then isolate
60. ce method and wait for the GC to become ready 3 Remove the column if installed 4 Plug the column fitting with a column nut and a no hole ferrule 5 Remove the old septum and replace it with a new one See To change the septum on the split splitless inlet 6 Inspect the O ring and replace it if it is hard and brittle or cracked See To change the liner and O ring on the split splitless inlet 7 Set the inlet to Split Mode 137 7 Checking for Leaks Back inlet split vent Front inlet split vent 138 oso co Configure the column as Inlet Unspecified Set the inlet temperature to 70 C Set the Total flow to 60 mL min Enter a pressure setpoint of 25 psi 172 kPa Make sure that the pressure supplied to the GC is at least 10 psi 70 kPa higher than the inlet pressure If pressure cannot be achieved there is either a large leak or the supply pressure is too low Set the Septum purge flow to 3 0 mL min Allow the inlet temperature to stabilize Temperature changes can invalidate the test Cap the septum purge fitting with the ECD TCD detector plug Back inlet purge vent O m c Front inlet Be O purge vent Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting 1 1 1 1 2 9 Checking for Leaks 7 lt lt Front purge vent shown plugged a From the keypad press Service Mode Select
61. consider the compound solubility in the injection solvent Change the solvent Use a retention gap Check purity of sample solvent For solvents with large differences in polarity or boiling points a mixed sample solvent can cause peak fronting Change the sample solvent Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Noisy Detector Including Wander Drift and Baseline Spikes Total noise Noise should be measured under normal operating conditions with a column connected and carrier gas on FID electrometer noise or drift flame off for instance will not provide much indication of how the detector will perform in practice because major sources of noise are not included in this measurement Noise typically has a high frequency component electronic in origin and lower frequency components that are referred to as wander and drift Wander is random in direction but at a lower frequency than the short term electronic noise Long term noise drift is a monotonic change in signal over a period that is long compared to the wander and electronic noise see below Terms like short and long are relative to the width of the chromatographic peaks In general one should measure noise over a period of time that is about 10 times the peak width at half height or 10 times the area height ratio for a Gaussian peak Measuring for longer times can over estimate noise shorter times may underestimate noise
62. ct Agilent for service fl oo gt me 5 o c0 40 o amp SSS 7 O o o A 1 8 8 ZT l hi I Ss lg a o Be o o e jo _ TT I If using cryo cooling e Check for sufficient cryo coolant e Check if operating limits have been exceeded 92 Agilent 7890 Series Troubleshooting Oven Never Heats Up GC Not Ready Symptoms 4 e Press Status to check for errors to report to Agilent The exhaust coming from the back of the GC is very hot Keep hands and face away from the exhaust vent Agilent 7890 Series Troubleshooting e Power cycle the GC e Check oven flapper operation 1 Increase oven temperature by at least 20 degrees 2 Verify that the oven flaps in the back of the GC are closed The figure below illustrates the location of the two oven flaps If the flap is stuck open or if the flaps are closed and the oven still does not heat contact Agilent
63. detector when lit is gt 20 pA Agilent 7890 Series Troubleshooting 195 Troubleshooting Tasks To Measure NPD Leakage Current 196 Load the analytical method Set the NPD Adjust Offset to Off and the Bead Voltage to 0 00 V Leave the NPD at operating temperature Leave flows on or off Press Front Det or Back Det then scroll to Output Verify that the output leakage current is stable and lt 1 0 pA The output should slowly drop toward 0 0 pA and should stabilize in the tenths of a picoamp Current gt 2 0pA indicates a problem If the current is gt 2 0pA do the following Inspect the jet for contamination Check the column or column adapter fitting for leaks Ensure that the metal sealing ring is not crushed or misaligned See To Maintain the NPD Collector Ceramic Insulators and Jet Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 To Check for a Plugged FID Jet The most common cause of FID ignition problems is a plugged or partially plugged jet If the jet is not completely plugged and the flame still ignites a secondary symptom will be lengthening peak retention times Jet plugging is most common with thick film high bleed or packed columns and high temperature applications It is best to operate the column oven within the temperature limits of the column and also to operate the FID at least 20 C hotter than the maximum oven temperature in the GC method If the FID jet is becoming p
64. down e Turns off to avoid column damage e Opens oven flaps in the back of the oven halfway e Flashes oven temperature setpoint Off e Turns off all flows for the column When viewed their parameters flash Off For example the septum purge and column flows for a split splitless inlet would turn off e Turns off all other heaters When viewed their temperature parameters flash Off e Attempts to turn on a shut down zone fail with an error message e Turns off the TCD filament e Turns off the FID or FPD ignitor and the air and fuel gas flows e Turns off the NPD bead and air and fuel gas flows e 7890B Communicates with 5977 MSD if present so the MSD can react to the shutdown event To recover from this state 1 Fix the cause of the shutdown Verify the carrier gas supply The GC requires a delivered gas pressure of 70 kPa 10 psi higher than the highest pressure used in the run See the Agilent GC GC MS and ALS Site Preparation Guide Check for a broken column near the inlet Check for leaks Replace the inlet septum Replace the inlet O ring Check the supply pressure 2 Press the key for the device that initiated the shutdown Scroll to the pneumatic parameter that is flashing Off then press On or Off 112 Agilent 7890 Series Troubleshooting Shutdown Symptoms 5 For example if the front inlet ran out of carrier gas press Front Inlet scroll to the pressure or flow parameter then press
65. dy the instruments change their settings based on each other s status For example e A GC shutdown may cause the MSD to shut down or otherwise protect itself e Venting the MSD causes changes in the GC to support the venting process e An MSD shutdown may cause the GC to change its settings to protect itself and the MSD e A loss of communications between the instruments may causes changes in one or both instruments e The GC sleep wake cycle triggers the MSD sleep wake cycle Gif available Because of this interaction always check the displays on both instruments and in the data system to learn the complete system status In general the GC display will present many MSD status and other information messages 12 Agilent 7890 Series Troubleshooting Concepts and General Tasks 1 Configurable Items to Always Keep Current Certain configurable items in the GC must always be kept current Failure to do so will lead to reduced sensitivity chromatographic errors and possible safety concerns If equipped with the optional G3494A or G3494B Barcode Reader accessory 7890B only you can directly scan parts data column liner and ALS syringe information into the GC without having to type it into the GC at the keypad Inlet and detector configuration Be sure to configure the GC and all related components to reflect an inlet or detector change Below are some examples of components to keep current after making changes to the
66. e Bake out the inlet See the following To Bakeout Contaminants from the Split Splitless Inlet To Bakeout Contaminants from the Multimode Inlet To Bakeout Contaminants from the Purged Packed Inlet To Bakeout Contaminants from the COC Inlet To Bakeout Contaminants from the PTV Inlet To Bakeout Contaminants from the VI Inlet e Clean the inlet See the following To Clean the Split Splitless Inlet To Clean the Multimode Inlet To Clean the Purged Packed Inlet To Clean the COC Inlet To Clean the Septumless Head on the PTV Inlet To Clean the Septum Seat in the Septum Head Assembly of the PTV Inlet To Clean the VI Agilent 7890 Series Troubleshooting 55 3 Chromatographic Symptoms Peak Fronting The figure below shows examples of the three types of peaks symmetric fronting and overloaded PN eas Symmetrical Fronting Overloaded If peak fronting or overloading occurs try the following 56 Verify that the injection volume is appropriate Column overload is the most common cause for fronting peaks Decrease injection volume dilute the sample and or increase the split ratio Change the column type or film thickness Ensure that the column is installed properly If not reinstall the column in the inlet Verify that the appropriate injection technique is being used This is usually related to erratic plunger depression or having sample in the syringe needle If using capillary splitless injection
67. e is still available and still has some gas in it try the older tank to see if noise decreases If the new gas is so badly contaminated that it saturates traps changing to the old one may show little improvement until the traps are replaced or regenerated This problem is most common with nitrogen carrier gas Deal with a reliable gas supplier For the TCD check for ambient air pressure fluctuations at the GC Air currents from a fan or air conditioner blowing across the GC may interfere with gas exiting the detector This is a possible though not very likely cause of noise since detectors are well protected Switching off the air current source or shielding the detector exit identifies this problem Install the TCD outlet restrictor G1532 60070 Loose connections in the detector or its signal path generate noise Verify proper reassembly after recent maintenance Inspect the detector for contamination If noise increases gradually to an unacceptable level check the following possible causes Bakeout the detector FID TCD uECD Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 e Inspect the detector for contamination Replace parts as needed See the 7890 Series Maintenance manual e Inspect the column and inlet for contamination e Inspect the FID or NPD jet for contamination To Check for a Plugged FID Jet To Replace an FID Jet To Check for a Plugged NPD Jet To Maintain the NPD Collector Cera
68. ector detector gas supply Check all gas trap indicators and dates Verify the gas purity Perform replicate runs several with a short interval between them then several with a large interval If the contamination peaks are larger for the runs made with the longer interval suspect contaminated gas the contamination has more time to deposit onto the column and liner Check for supply tubing and fitting contamination If you suspect that there is contamination in the detector perform the bakeout procedure FID TCD uECD Verify the operation of the detectors Replace the contaminated detector parts To Maintain the NPD Collector Ceramic Insulators and Jet Maintaining the FID Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Larger Peaks Than Expected Agilent 7890 Series Troubleshooting e Check each configured column s dimensions against the actual column dimensions See Configurable Items to Always Keep Current Refer to To configure a single column or To configure multiple columns in the Advanced User Guide for procedures on configuring columns Check the autosampler injection volume In the normal injection mode the sampler uses fast injection to deliver a representative amount of the sample Fast injection minimizes needle fractionation Chromatograms from manual injection or slower auto injection devices show higher levels of low molecular weight materials versus higher molecular wei
69. ed maintenance on the NPD first verify that the detector was reassembled properly before troubleshooting detector problems 1 2 Agilent 7890 Series Troubleshooting Replace the ceramic insulators Restest Set the bead voltage to 0 0 V Turn off the adjust offset View the output leakage current Remove the bead and store in a safe place Remove the three screws that secure the lid in place then remove the lid Examine the interconnect spring Make sure that the interconnect spring is not damaged bent or dirty The interconnect spring should be touching the bottom of the collector If the inteconnect spring is damaged bent or dirty call Agilent for service Correct If the interconnect spring is not damaged or dirty and the detector output signal is still high contact Agilent for service 27 28 2 ALS and Detector Symptoms FID Fails Baseline Test If you have just performed maintenance on the FID first verify that the detector was reassembled properly before troubleshooting detector problems If the FID fails the baseline test e Ensure the purity and quality of the gas e Replace dirty expended chemical traps e Bakeout the detector Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2 To Resolve Low Sensitivity with an FID See To Resolve Low Sensitivity with an FID Agilent 7890 Series Troubleshooting 29 2 ALS and Detector Symptoms FID Does Not Ignite 30 Ver
70. em in two parts external leak points and GC leak points External leak points include the gas cylinder or gas purifier regulator and its fittings supply shutoff valves and connections to the GC supply fittings GC leak points include inlets detectors column connections valve connections and connections between flow modules and inlets detectors Hydrogen H2 is flammable and is an explosion hazard when mixed with air in an enclosed space for example a flow meter Purge flowmeters with inert gas as needed Always measure gases individually Always turn off detectors to prevent flame bead autoignition Hazardous sample gases may be present 126 1 2 Gather the following Electronic leak detector capable of detecting the gas type 7 16 in 9 16 in and 1 4 in wrenches for tightening Swagelok and column fittings Check any potential leak points associated with any maintenance recently performed Check GC fittings and connections that undergo thermal cycling since thermal cycling tends to loosen some fitting types Use the electronic leak detector to determine if a fitting is leaking Start by checking any newly made connections first Remember to check connections in the gas supply lines after changing traps or supply cylinders Agilent 7890 Series Troubleshooting Checking for Leaks 7 To Check for External Leaks Check for leaks at these connections Riv
71. en the column adapter connection Re install if needed e Check the plugged column fitting and the septum purge cap To Perform a PP Inlet Pressure Decay Test Agilent 7890 Series Troubleshooting The pressure decay test checks for leaks from the inlet flow module up to the column fitting After performing maintenance first check for leaks in externally accessible areas See To Check for External Leaks If a leak is known to exist check the externally accessible inlet fittings first especially any connection that has seen recent maintenance such as the septum nut column adapter column connection and so forth The pressure decay leak test described below requires removing the column and capping the inlet column fitting This test can cannot find the following types of leaks The test can find leaks at the The test cannot find leaks at the septum column fitting septum nut gas supply bulkhead fittings to the flow module glass insert O ring seal adapter and ferrule inlet body 149 7 150 Checking for Leaks The test can find leaks at the The test cannot find leaks at the top insert weldment seals within the tubing between the inlet flow module and the inlet body 1 Gather the following see Consumables and parts for the purged packed inlet No hole ferrule 1 4 inch wrench 7 16 inch wrench Heat resistant gloves if the inlet is hot 9 16 inch wrench 1 8 and 1 4 inch S
72. ends to core the septum and drop pieces into the sample causing contamination and ghost peaks Perform complete inlet maintenance Replace all consumable parts and bake out the inlet Check for sample carryover from previous runs Make several no injection blank runs and see if the ghost peaks go away or get smaller Check the septum purge flow If it is too low the septum may have collected contamination or condensate may be clogged in the purge line For SS MMI PTV and PP inlets Set the purge flow to at least 3 mL min to keep the septum clean For COC inlets set the septum purge flow to at least 15 mL min Measure the flow See To Measure a Column Flow Check all gas trap indicators and dates Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 e Verify the gas purity Perform replicate runs several with a short interval between them then several with a large interval If the contamination peaks are larger for the runs made with the longer interval suspect contaminated gas the contamination has more time to deposit onto the column and liner e Check for supply tubing and fitting contamination e If you suspect that there is contamination in the inlet perform the bakeout procedure SS MMI PP COC PTV VI e Verify the operation of the inlets Clean the inlet and replace the contaminated inlet parts To Clean the Split Splitless Inlet To Clean the Purged Packed Inlet To Clean the Cool O
73. entering and contaminating the GC system or damaging the column Some traps are single purpose for the removal of oxygen moisture or hydrocarbons while combination traps remove all those contaminants The best way to know when it is time to change a trap is to use an indicating trap which should be placed after a high capacity trap Agilent recommends using glass indicating traps such the Gas Clean Filter system whose clear tubes display a distinct color change in response to contamination This color change tells the analyst it is time to change traps If no indicating traps are used it is best to follow the manufacturer s recommendation for replacement frequency Typically the manufacturer will state how many gas cylinders can be purified with a given trap If desired it is possible to estimate when to replace the trap by performing a rough calculation For example you have a standard K size cylinder with He at 99 995 purity that contains 7 800 L of He Assuming a worst case scenario in which the remaining 0 005 is all oxygen you should have 39 mL or about 56 mg of O2 in the tank Agilent s OT3 oxygen trap for example has a capacity of 600 mg O2 Therefore you need to replace the OT3 trap every 10 cylinders This is just a rough estimate and it is prudent to change traps too early rather than too late Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 To Check a Split Vent Line for Contamination T
74. eptum septum nut liner O ring seal inlet body flow manifold split vent valve flow manifold septum purge valve split vent tubing and trap septum purge tubing seals within the tubing between the inlet flow module and the inlet body column fitting gas supply bulkhead fittings to the flow module tubing and connections in a transfer line connected to the inlet 1 Gather the following see Consumables and parts for the Multimode inlet No hole ferrule 1 4 inch wrench Heat resistant gloves if the inlet is hot Column nut New septum O ring ECD TCD Detector plug part no 5060 9055 2 Load the inlet maintenance method and wait for the GC to become ready 3 Remove the column if installed 4 Plug the column fitting with a column nut and a no hole ferrule 5 Remove the old septum and replace it with a new one See To change the septum on the multimode inlet 6 Inspect the O ring and replace it if it is hard and brittle or cracked See To change the liner and O ring on the Multimode inlet 7 Set the inlet to Split Mode 8 Configure the column as Inlet Unspecified 9 Set the inlet temperature to 70 C 145 7 Checking for Leaks 10 Set the Total flow to 60 mL min 11 Enter a pressure setpoint of 25 psi 172 kPa Make sure that the pressure supplied to the GC is at least 10 psi 70 kPa higher than the inlet pressure 12 If pressure cannot be achieved there is either a lar
75. eries Gas Chromatograph Troubleshooting 2 ALS and Detector Symptoms Plunger Errors 18 Vial Mishandled by ALS 7693A 19 Alignment Light on 7693A 7650A Injector Tower is On 21 Vial Mishandled by ALS 7683 22 Alignment Light on 7683B Injector Toweris On 24 Syringe Needle Bends During Injection into Inlet 25 FID Fails Leakage Current Test 26 NPD Fails Leakage Current Test 27 FID Fails Baseline Test 28 To Resolve Low Sensitivity with an FID 29 FID Does Not Ignite 30 FID Ignitor Does Not Glow During Ignition Sequence 31 Corrosion in FID Collector and Ignitor Glow Plug 33 FPD Does Not Ignite 34 NPD Adjust Offset Process Fails 36 NPD Bead Will Not Ignite 37 FPD Temperature Will Not Become Ready 38 Blinking Not Ready Light Detector Hardware Fault TCD Filament Voltage 39 Shutdown Defective Device 40 phe Agilent Technologies 2 ALS and Detector Symptoms Plunger Errors 18 Procedure If the ALS reports a front or back plunger error check the following possible causes The syringe plunger is sticking or is not securely connected to the plunger carrier The plunger solenoid is binding The plunger carrier encoder is inoperable The autoinjector plunger carrier mechanism will not move The plunger does not move freely due to sample residue or wear Install a new syringe making sure to prime the syringe with solvent before installing Remove the syringe and check it for plunger stickiness or binding
76. es the test restore the GC to operating condition Remove any caps plugs Reinstall the column Restore the correct column configuration Load the operating method 140 Agilent 7890 Series Troubleshooting Checking for Leaks 7 To Correct Leaks in the Split Splitless Inlet Agilent 7890 Series Troubleshooting If the inlet fails a pressure decay test check the following Check the caps plugs used in the test make sure each is correctly installed and tight If you performed the leak test after performing maintenance check for proper installation of the part s handled during the maintenance Check the tightness of the septum nut See To change the septum on the split Splitless inlet Check the septum Replace if old or damaged Check the insert assembly installation Check the liner and liner O ring See To change the liner and O ring on the split splitless inlet If you changed the gold seal verify correct installation See To replace the gold seal on the split splitless inlet Make sure the inlet temperature remained constant during the test If these items do not resolve the problem contact Agilent for service 141 7 Checking for Leaks To Check for Leaks in a Multimode Inlet 142 This procedures describes how to check for and fix leaks in the Multimode inlet Follow the procedures below based on the inlet s symptoms Cannot Reach Pressure Setpoint If the Multimode EPC inlet does not reach
77. est is unsuccessful do the following e Check the LAN cabling e Verify the IP address subnet mask and gateway addresses e Make sure all network devices hubs switches and so forth are turned on properly connected and working e Check for a defective LAN card in the PC e If using a direct PC to GC setup make sure you are using a crossover cable If using a setup with a hub or switch that is connecting to a building or site LAN make sure you are NOT using a crossover cable 121 6 GC Power On and Communication Symptoms GC Cannot Communicate with 5977 MSD 122 First check that GC to MS communications are enabled a Press Aux Det b Scroll to MS2GC If the entry reads Off press On Yes If the entry reads Connecting but does not connect continue troubleshooting Check that the GC IP address is correctly entered and correct as needed Go to Options gt Communications Check that the MS IP address is correctly entered into the GC Under Options gt Communications scroll to Mass Spec to see the current MS IP address Compare it against the IP address shown on the MS display Use the MS keypad to check the MS and GC IP addresses entered into the MS They must exactly match those entered into the GC If the addresses are correct in both the GC and the MS ping the GC and MS from a computer on the same local LAN See PC Cannot Communicate with GC for more information about the PC ping com
78. et the bead voltage to 0 0 V 3 Cool the NPD to 100 C WARNING Be careful The detector may be hot enough to cause burns If the detector is hot wear heat resistant gloves to protect your hands 4 Remove the bead and store it carefully until reinstallation 5 Insert the NPD flowmeter adapter tool into the NPD collector 6 Attach the flow measuring insert to the NPD flowmeter adapter tool 174 Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 7 Place the flowmeter tubing over the flow measuring insert to begin measuring flows Agilent 7890 Series Troubleshooting 175 8 Troubleshooting Tasks To Measure a Split Vent or Septum Purge Flow Back inlet split vent Front inlet split vent 176 Note that the GC reports flows calibrated to 25 C and 1 atmosphere Correct flowmeter results accordingly Hydrogen H2 is flammable and is an explosion hazard when mixed with air in an enclosed space for example a flow meter Purge flowmeters with inert gas as needed Always measure gases individually Always turn off detectors to prevent flame bead autoignition Septum purge and split vent flows exit through the pneumatic module at the top rear of the GC See the figure below Back inlet purge o vent O m Front inlet 9 O purge vent To measure split vent or septum
79. evaluation 64 Sensitivity 65 Contamination high baseline 66 Low Peak Area or Height Low Sensitivity 67 To Resolve Low Sensitivity with an FID 68 FID Flame Goes Out During a Run and Attempts to Reignite 70 Troubleshooting FID Baseline Output Above 20 pA 72 FID Baseline Output at Maximum 8 Million 73 FPD Flame Goes Out During a Run and Attempts to Reignite 74 FPD Quenching Repeatability 75 FPD Output Too High or Too Low 76 FPD Low Peak Areas 77 FPD Large Peak Width at Half Height 78 FPD Baseline Output High gt 20pA 79 NPD Solvent Quenching 80 NPD Response Low 81 NPD Baseline Output gt 8 million 83 NPD Adjust Offset Process Not Functioning Properly 84 NPD Low Selectivity 85 Negative Peaks Seen with TCD 86 TCD Baseline Has Dampened Sinusoidal Noise Trailing Peaks Ringing Baseline 87 TCD Peaks Have Negative Dip on Tail 88 4 GC Not Ready Symptoms GC Never Becomes Ready 90 Flow Never Becomes Ready 91 Oven Temperature Never Cools Down Cools Very Slowly 92 Oven Never HeatsUp 93 Temperature Never Becomes Ready 94 Cannot Seta Flow or Pressure 95 A Gas Does Not Reach Setpoint Pressure or Flow 96 A Gas Exceeds Pressure Setpoint or Flow 97 The Inlet Pressure or Flow Fluctuates 98 Cannot Maintain a Pressure as Low as the Setpoint ona Split Inlet 99 The Measured Column Flow Does Not Equal the Displayed Flow 100 FID Does Not Ignite 101 FID Ignitor Does Not Glow During Injection Sequence 102 FID or NPD Measured Hydrogen
80. for Leaks Verify that the Test pressure is acceptable Typically the default pressure of 10 psi works well If desired enter a different inlet pressure For repeatable results use the same value for the same hardware Enter a higher test pressure if using a column that produces high backpressure Scroll to Test Inlet and press On Yes After a moment the test stabilizes The TotalFlow reading shows the total flow of carrier gas through the inlet The Col reading shows the flow through the column The approximate leak rate is TotalFlow Col in mL min Consider the inlet leak free if the Col reading approximately equals the TotalFlow reading While monitoring the readings tighten fittings replace the septum change the liner O ring and so forth as needed If the repair stops the leak you will see the Col reading decrease to be approximately equal to the TotalFlow reading If you ran the test on a leak free inlet before performing maintenance the leak test result after maintenance should be about the same as it was before maintenance 7 If the test still fails Replace the septum Reinstall the column into the inlet Replace the liner and liner O ring Open the split vent trap and check the O ring seating Replace the split vent trap if needed If the test passes but you still suspect an inlet leak perform a pressure decay leak test See To Perform a SS Pressure Decay Leak Test To Perform a MMI Pressure
81. ge leak or the supply pressure is too low 13 Set the Septum purge flow to 3 0 mL min 14 Allow the inlet temperature to stabilize Temperature changes can invalidate the test 15 Cap the septum purge fitting with the ECD TCD detector plug Back inlet split Back inlet purge vent vent Front inlet split O vent Front inlet Be O purge vent A Front purge vent shown plugged 146 Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting 16 1 18 19 2 21 Checking forLeaks 7 From the keypad press Service Mode Select Diagnostics gt Front or Back Inlet gt Pneumatics Control gt Septum Purge control Scroll to the Constant duty cycle and enter 50 Wait 10 seconds Press Front or Back Inlet Scroll to Pressure and press Off No Quickly turn off the carrier gas supply at its source Monitor the pressure for 10 minutes Use the timer by pressing Time and Enter A pressure drop of less than 0 5 psig 0 05 psi min or less 3 4 kPa or 0 34 kPa min is acceptable If the pressure drops much faster than the acceptable rate see To Correct Leaks in the Multimode Inlet Retest Note that liner size impacts pressure drop An inlet with a smaller volume liner does not tolerate as large a leak rate as an inlet with a larger volume liner After the inlet passes the test restore the GC to operating condition Re
82. ght materials because the volatiles boil out of the needle faster than the higher weight materials Check the vial caps Loose vial caps can cause selective loss of lighter materials from a sample The cap should not rotate easily if installed properly Check configured syringe size Some syringe sizes are specified at half capacity If the maximum syringe volume is marked at half height on the barrel not at the top of the barrel enter twice the labeled volume when configuring the syringe size 47 3 Chromatographic Symptoms Peaks Not Displayed No Peaks 48 e If using an autosampler Ensure that there is sample in the vial Verify that the ALS plunger carriage is secured to the syringe plunger Check that the syringe is installed correctly and draws sample Verify that the turret tray is loaded correctly and injections are not from out of sequence vials Watch to see that the sample is pulled into the syringe Verify the detector in use is assigned to a signal Check the column for proper installation Ensure that the column is not plugged See To Measure a Column Flow Perform column maintenance Check for leaks See Checking for Leaks Check the flow settings then measure the actual detector flows See To Measure a Detector Flow Some samples change with heat or ultraviolet light Check sample stability Check the sample level in the vial If the sample is viscous try the f
83. he air or into the GC oven Reconfigure the GC every time the gas type is changed If the GC is configured to a gas other than what is actually being plumbed incorrect flow rates will result To confirm the gas configuration 1 Press Config 2 Scroll to the appropriate detector or column item on the display and press Enter to see the type of gas configured 14 Agilent 7890 Series Troubleshooting Concepts and General Tasks 1 To View the Run Log Maintenance Log and Event Log The GC maintains internal event logs each of which holds up to 250 entries Use these logs to troubleshoot problems especially when a message no longer appears on the display To access the logs press Logs to toggle to the desired log The display will indicate the number of entries the log contains Scroll through the list Run Log For each run the run log records deviations from the planned method This log is overwritten at the start of each run The run log information can be used for Good Laboratory Practice GLP standards and can be uploaded to an Agilent data system When the Run Log contains entries the RunLog LED lights Maintenance Log The maintenance log contains an entry for each time an Early Maintenance Feedback limit is reached reset or changed The log records details such as the counter item the counter value the new counter value and whether or not the counter was reset indicating a part replacement When the ma
84. his procedure applies to the multimode and split splitless inlets WARNING Be careful The oven inlet and or detector may be hot enough to cause burns If the oven inlet or detector is hot wear heat resistant gloves to protect your hands 1 Gather the following 7 16 inch wrench Wrench hex for changing septum Heat resistant gloves if the inlet is hot Cleaning brushes 2 Load the inlet maintenance method and wait for the GC to become ready 3 Loosen the 1 8 inch Swagelok nut that seals the copper split vent line to the injection port 4 Inspect the 1 8 inch copper split line for condensed sample Flush or replace the copper split vent line 5 Remove the septum head 6 Check the split tube fitting in the shell weldment for blockage Clean the split tube with a brush and suitable solvent 7 Reassemble the split splitless inlet and run the split vent restriction test to test for restrictions in the split vent flow path If the inlet still fails suspect flow module contamination or defects Agilent 7890 Series Troubleshooting 203 8 Troubleshooting Tasks 8 Check for leaks Run the pressure decay test See To Perform a SS Pressure Decay Leak Test or To Perform a MMI Pressure Decay Leak Test 204 Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 To Ignore a Devices Readiness State CAUTION By default the GC monitors the status of all configured devices inlets detectors valve bo
85. ify that the Lit Offset is lt 2 0 pA Ensure that the FID temperature is high enough for ignition gt 150 C Agilent recommends gt 300 C Check that the FID ignitor glows during ignition sequence See To Verify FID Ignitor Function During Ignition Sequence Check that the air and hydrogen pressures meet Agilent s recommendations hydrogen gt 35 psi 210 kPa and air gt 55 psi 380 kPa See the Agilent GC GC MS and ALS Site Preparation Guide Try increasing the supply pressures to the FID flow module This makes the flame easier to light without changing the setpoints Increase hydrogen flow and decrease or turn off makeup gas flow until ignition occurs then reduce them toward the method values Experiment for the best values Increasing hydrogen flow and decreasing makeup flow will help the FID ignite more easily If it will light under these modified conditions the cause could be a partially clogged jet a weak ignitor or a leak at the column fitting Check for a plugged or partially plugged jet See To Check for a Plugged FID Jet Measure the FID flow rates Actual flow rates should be within 10 of the setpoint See FID starting conditions The hydrogen air ratio greatly impacts ignition Nonoptimal flow settings can prevent flame ignition See To Measure a Detector Flow There could be a large leak in the system if the flame still will not light Large leaks result in measured flow rates bei
86. important example is when an inlet or detector heater is defective Normally this fault prevents the GC from becoming ready and starting a run However you can set the GC to ignore this problem so that you can use the other inlet or detector until the device is repaired Not all devices can be ignored You can ignore the readiness state of inlets detectors the oven or an EPC module The readiness state of other devices and components can never be ignored for example injection devices such as a switching valve or automatic liquid sampler To ignore the status of a device 1 Turn off the device s heater and gas flows as applicable Make sure that it cannot create a safety hazard 2 Press Config then select the element 3 Scroll to Ignore Ready and press On Yes to set it to True You can now use the GC until the device is repaired Do not ignore the readiness state of a device that is being used unless you do not care if it reaches setpoint Be sure to return a broken device to Ignore Ready False after it is repaired Otherwise its state temperature flow pressure and so forth will continue to be ignored even if using this device in the analysis 40 To consider a device s readiness set Ignore Ready to False Agilent 7890 Series Troubleshooting Agilent 7890 Series Gas Chromatograph Troubleshooting 3 Chromatographic Symptoms Retention Times Not Repeatable 42 Peak Areas Not Repeatable 43 Contam
87. ination or Carryover 44 Larger Peaks Than Expected 47 Peaks Not Displayed No Peaks 48 Baseline Rise During Oven Temperature Program 50 Poor Peak Resolution 51 Peak Tailing 52 Peak Boiling Point or Molecular Weight Discrimination Poor 54 Sample Decomposition in Inlet Missing Peaks 55 Peak Fronting 56 Noisy Detector Including Wander Drift and Baseline Spikes 57 Microcell Electron Capture Detector uECD Noise and Sensitivity 63 Low Peak Area or Height Low Sensitivity 67 FID Flame Goes Out During a Run and Attempts to Reignite 70 FID Baseline Output Above 20 pA 72 FID Baseline Output at Maximum 8 Million 73 FPD Flame Goes Out During a Run and Attempts to Reignite 74 FPD Quenching Repeatability 75 FPD Output Too High or Too Low 76 FPD Low Peak Areas 77 FPD Large Peak Width at Half Height 78 FPD Baseline Output High gt 20 pA 79 FPD Chromatographic Output Showing Clipped Peaks HIDDEN NPD Solvent Quenching 80 NPD Response Low 81 NPD Baseline Output gt 8 million 83 NPD Adjust Offset Process Not Functioning Properly 84 NPD Low Selectivity 85 Negative Peaks Seen with TCD 86 TCD Baseline Has Dampened Sinusoidal Noise Trailing Peaks Ringing Baseline 87 TCD Peaks Have Negative Dip on Tail 88 ait Agilent Technologies 3 Chromatographic Symptoms Retention Times Not Repeatable e Replace the septum e Check for leaks in the inlet liner as applicable and column connection See Checking for Leaks
88. ing change in the response by making split and then splitless injection all other method parameters remaining the same If using split mode verify the split flow using a flow meter 2 Check all flow rates See Measuring FID TCD uECD and FPD flows Agilent 7890 Series Troubleshooting 65 3 Chromatographic Symptoms 3 Confirm that complete inlet maintenance has been performed This includes trimming and re installing the column Verify that the injecting device is working properly If the method uses a sampling valve make a direct syringe injection of concentration similar to that introduced by the valve Rule out a problem with the valve Inspect the mixing liner in the makeup gas adapter A small piece of graphite or sample contamination will reduce sensitivity See To Replace the uECD Fused Silica Indented Mixing Liner and Install the Makeup Gas Adapter Contamination high baseline If the ECD has a baseline higher than expected for its age check the following e Rule out all other possible causes See Sensitivity above Also check carrier and detector gas supplies supply gas traps and the column Inspect the mixing liner in the makeup gas adapter A small piece of graphite can contaminate results See To Replace the uECD Fused Silica Indented Mixing Liner and Install the Makeup Gas Adapter If the detector baseline is gt 500 Hz regardless of detector age bakeout the detector Let it run for
89. inlet Check the total flow setting Total flow must be high enough to maintain inlet pressure throughout the run Wide bore columns require higher flow rates Typically 50 mL min is sufficient To increase total flow Increase split ratio if in split mode Increase the purge flow for splitless mode Put your thumb or a septum over the split vent exhaust If the inlet pressure begins to rise to the setpoint call Agilent for service If the pressure remains low continue with the next step Perform the inlet run leak check See To Perform an Inlet Leak Check The total flow provides an indication of the magnitude of the leak Monitor the total flow while checking tightening fittings Septum nut Column Split vent trap O rings Liner O rings Gold seal Agilent 7890 Series Troubleshooting Checking for Leaks 7 Split vent line connection to the inlet body Flow block fittings on the flow manifold Alternately use an electronic leak detector to check these fittings connections If these checks do not resolve the problem contact Agilent for service Low Sensitivity or Poor Repeatability A small leak in the split splitless EPC inlet can cause low sensitivity or poor repeatability Check for and isolate a small leak as described below If you have recently performed maintenance first check for leaks on any fittings parts you handled 1 Perform the inlet pressure decay test See To Perform a SS Pressure Decay
90. inlet or detector Liners The appropriateness of liner type varies depending on the GC inlet mode for example split mode versus splitless mode and the analysis FPD filters The FPD filters require different gas flows to function properly Configure the flow according to the FPD filter installed phosphorus versus sulfur FID and NPD jets Use the jet appropriate for the type of column installed capillary column versus packed column NPD bead type Always configure the NPD bead type An incorrect type can lead to poor performance or premature bead failure Column configuration Reconfigure the GC every time a column is trimmed or changed Also verify that the data system reflects the correct column type length id and film thickness The GC relies on this information to calculate flows Not updating the GC after altering a column causes incorrect flows changed or incorrect split ratios retention time changes and peak shifts Agilent 7890 Series Troubleshooting 13 1 Concepts and General Tasks Automatic Liquid Sampler configuration Keep the Automatic Liquid Sampler ALS configuration up to date to ensure proper operation ALS items to keep current include injector position installed syringe size and solvent and waste bottle usage Gas configuration WARNING Always configure the GC appropriately when working with hydrogen Hydrogen leaks quickly and poses a safety concern if too much of it is released into t
91. intenance log is full the GC overwrites entries beginning with the oldest Event Log The event log records events such as shutdowns warnings faults and GC state changes start run stop run and so forth that occur during GC operation When the event log is full the GC overwrites entries beginning with the oldest Agilent 7890 Series Troubleshooting 15 1 Concepts and General Tasks Information to Obtain Before Calling Agilent for Service Gather the following information before contacting Agilent for service e Symptoms e Problem description e Hardware installed and parameters configuration when the error occurred sample supply gas type gas flow rates detectors inlets installed and so forth e Any messages that appear on the GC display e Results of any troubleshooting tests you have run e Instrument details Obtain the following information e GC serial number which can be found on a sticker located beneath the keypad on the bottom right corner of the GC e GC firmware revision press Status then Clear e GC power configuration located on a label on the back panel of the GC to the left of the GC power cable e Oven configuration fast or slow heating e Press the Status key to display previous Error Not Ready and Shutdown messages To obtain service support contact numbers see the Agilent Web site at www agilent com chem 16 Agilent 7890 Series Troubleshooting Agilent 7890 S
92. k e Use nitrogen as the makeup gas e Set the total column flow and makeup gas to less than 10 mL min e Increase the air flow by 10 mL min e Increase the detector temperature to 325 C e Implement an Agilent Dean s switch solvent vent solution Agilent 7890 Series Troubleshooting NPD Response Low Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Perform complete inlet maintenance Replace all consumable parts and bake out the inlet Perform column maintenance Bake out contaminants as needed Verify correct column installation A large concentration of solvent has extinguished the hydrogen air plasma Increase the bead voltage Run the makeup gas at a flow rate of 5 mL min Verify that there is hydrogen coming from the external supply Check that flow and pressure are turned on at the keyboard The hydrogen flow rate should be between 1 0 and 5 5 mL min Measure the actual gas flow at the detector See To Measure a Detector Flow Check for a partially plugged jet See To Check for a Plugged FID Jet If the upper ceramic insulator is contaminated a high offset 2 to 15 pA or more will occur when the bead is off This directly affects sensitivity Replace the ceramic insulator 81 3 82 Chromatographic Symptoms e Verify that the bead is activated Look through the vent hole on the detector lid to see if the bead is glowing orange If the bead is not glowing check the detector b
93. l injections in splitless or gas saver mode you may need to press Prep Run to prepare the inlet for the injection Do this for example To toggle the inlet purge valve before a splitless injection To prepare for a pulsed injection To turn off gas saver For more information on Prep Run see the Agilent 7890 GC Advanced User Guide Agilent 7890 Series Troubleshooting GC Not Ready Symptoms 4 Flow Never Becomes Ready If the gas flow never becomes ready check for the following e Check the supply gas for sufficient delivery pressure e Check the restrictors installed in the Aux EPC module See Restrictors in the Advanced User Guide e Check the configured gas type The configured gas type must match the actual gas plumbed to the GC e Check for leaks in the gas delivery plumbing and the GC See Checking for Leaks Agilent 7890 Series Troubleshooting 91 4 GC Not Ready Symptoms Oven Temperature Never Cools Down Cools Very Slowly If the oven does not cool down or cools down very slowly WARNING The exhaust coming from the back of the GC is very hot Keep hands and face away from the exhaust vent e Check oven flapper operation 1 Decrease oven temperature by at least 20 degrees 2 Verify that the oven flaps in the back of the GC are open Listen to verify that the fan is operating The figure below illustrates the location of the two oven flaps If the flaps are not operating smoothly conta
94. l time built in leak check for all inlets This check is most useful for finding inlet leaks during and after inlet maintenance While not as thorough or sensitive as a complete inlet pressure test it is normally performed with the column installed and configured and provides a quick assurance that the inlet is reasonably leak free Agilent recommends running the check before and during inlet maintenance so that as you tighten any fittings you can watch the inlet stop leaking The test is appropriate for all applications although some may require more robust leak testing The inlet leak check finds leaks at the e Inlet column fitting e Gold seal as applicable e Split vent trap housing as applicable e Septum nut and septum as applicable e Insert weldment nut septum head assembly as applicable To run the test 1 At the GC keypad press Service Mode scroll to Front inlet leak check or Back inlet leak check then press Enter 2 The display will be similar to Figure 4 FRONT INLET LEAK CHECK TotalFlow 1 74 Col 1 34 lt Test Inlet ON to Start Test pressure 10 0 psi Warning if check flow OFF Fault if check flow OFF Last test results Tue Oct 20 16 07 2009 Test flow OK 4 8 Reset the test results yes Figure4 Example front inlet leak check display Example assumes a test has been previously run Scroll the display to see all lines Agilent 7890 Series Troubleshooting 131 7 132 Checking
95. lace must be tight Perform FID maintenance if these parts are corroded or oxidized T 20 Torx screws 3 Ignitor Knurled nut 32 Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2 Corrosion in FID Collector and Ignitor Glow Plug Agilent recommends inspecting the collector and ignitor glow plug for corrosion while performing maintenance on the FID The FID combustion process results in condensation This condensation combined with chlorinated solvents or samples causes corrosion and sensitivity loss To avoid corrosion keep the detector temperature above 300 C Agilent 7890 Series Troubleshooting 33 2 ALS and Detector Symptoms FPD Does Not Ignite 34 e Check that the FPD temperature is high enough for ignition gt 150 C e Check FPD flow rates and that they match the type of filter installed in the FPD The hydrogen air ratio greatly impacts ignition Nonoptimal flow settings can prevent flame ignition Table 1 FPD recommended flows Sulfur mode flows mL min Phosphorus mode flows mL min Carrier hydrogen helium nitrogen argon Packed columns Capillary columns Detector gases Hydrogen Air Carrier makeup 10 to 60 1to5 60 60 60 10 to 60 1to5 60 60 60 Table 2 FPD recommended flows Sulfur mode flows mL min Phosphorus mode flows mL min Carrier hydrogen helium nitrogen argon Packed columns Capillary colum
96. lent Instrument Utilities you can also use it to remotely run an inlet leak check for selected inlet types If the inlet passes the inlet leak check but you still suspect a leak in the inlet you can use the Instrument Utilities software to perform a pressure decay test for most inlets You can also perform a manual pressure decay test on any inlet Any inlet that passes the inlet pressure decay test can be considered leak free e To Perform a SS Pressure Decay Leak Test e To Perform a MMI Pressure Decay Test e To Perform a PP Pressure Decay Leak Test e To Perform a COC Pressure Decay Leak Test e To Perform a PTV Pressure Decay Test e To Perform a VI Pressure Decay Test Use an electronic leak detector to check column connections and tubing connections See also e To Check for Leaks in a Split Splitless Inlet e To Check for Leaks in a Multimode Inlet e Leaks in Capillary Flow Fittings 129 7 Checking for Leaks Leaks in Capillary Flow Fittings For capillary flow fittings a leak usually indicates that the fitting has been overtightened Unless the fitting is obviously loose do not tighten it further Instead remove the connection trim the column end and install it again See To Attach a Capillary Column Using SilTite Metal Fittings Also inspect the plate and connection for a broken column tip 130 Agilent 7890 Series Troubleshooting Checking for Leaks 7 To Perform an Inlet Leak Check The GC provides a rea
97. limits to set the service due indicator or to force the GC to go Not ready The two limits are Warning if pressure check If the measured pressure exceeds the limit turn on the service due indicator Fault if pressure check If the measured pressure exceeds the limit make the GC Not Ready To set a warning limit a Press Service Mode scroll to Front inlet trap check or to Back inlet trap check then press Enter b Scroll to the desired limit c Enter a limit using the keypad then press Enter To disable a warning select it then press Off No 185 8 Troubleshooting Tasks The test is now set up 6 Periodically rerun the test When the test fails replace the split vent trap To clear a Not Ready condition or to turn off the Service Due indicator 1 Press Service Mode scroll to Front inlet trap check or to Back inlet trap check then press Enter 2 Scroll to Reset the test results and press On Yes To disable a warning limit for the inlet trap check 1 Press Service Mode scroll to Front inlet trap check or Back inlet trap check then press Enter 2 Scroll to the warning then press Off No 186 Agilent 7890 Series Troubleshooting To Run the Inlet Trap Check Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 From the GC keypad Press Service Mode scroll to Front inlet trap check or Back inlet trap check then press Enter The display will be similar to Figure 5
98. lit Vent Line Backpressure Agilent provides a built in test that measures backpressure in the split vent trap and line for the split splitless multimode PTV and VI inlets The test measures the pressure developed in the split vent flow path at a given user selected flow rate This flow rate can be your method Split flow setpoint or the default 400 mL min used by Agilent to compare typical values By running the test on a clean system you can establish a baseline for expected backpressure in the split vent line Then you can re run the test periodically to determine whether or not the trap needs to be replaced before it impacts your chromatography The pressure measured by the test depends on e The liner installed e The flow rate used Therefore the actual measured value will vary between different setups and from GC to GC The test checks for e Liner restriction e Contamination on the gold seal split splitless inlet only e Restrictions in the split vent line such as condensed sample contamination in the split vent line and trap The test can also provide a measure of suitability for the installed hardware Run the test using your method s setpoints and hardware If the measured test pressure is close to the desired column head pressure this means that even a minor amount of restriction in the split vent line can cause the GC to become not ready You may wish to install a different liner or adjust the method F
99. llowing Check the caps plugs used in the test make sure each is correctly installed and tight If you performed the leak test after performing maintenance check for proper installation of the part s handled during the maintenance Check the tightness of the septum nut See To change the septum on the purged packed inlet Check the septum Replace if old or damaged Check that the top insert weldment is installed tightly Replace the O ring See To change the O ring on the purged packed inlet Also check the glass insert See To change the glass insert on a PP inlet Replace the ferrule seal on the adapter Make sure the inlet temperature remained constant during the test If these items do not resolve the problem contact Agilent for service 153 7 Checking for Leaks To Perform a COC Pressure Decay Leak Test Use the Agilent Instrument Utilities Cool On Column Inlet Pressure Decay Test to determine if the inlet is leaking Open the software select the GC and run the test for the inlet If the Instrument Utilities software is not available see the procedure below If the test fails e Check the plugged column fitting and the septum purge cap e Tighten the septum nut e Replace the septum if necessary To Perform a COC Pressure Decay Test The pressure decay test checks for leaks from the inlet flow module up to the column fitting After performing maintenance first check for leaks in externally a
100. lugged actual H2 Makeup and Capillary carrier flows will be lower than the values indicated by the GC To check for a plugged FID jet 1 Leave the column installed in the FID If already removed cap off the detector column fitting in the oven Leaving the column installed will determine if the column is installed too high in the jet plugging the orifice 2 Set the makeup flow to Off Confirm a reading on the GC display of 0 0 mL min for actual makeup flow If not 0 0 follow the procedure To Zero the EPC Module Pressure Sensor 3 Set the hydrogen flow to 75 mL minute increase the H2 supply pressure as needed to achieve this flow rate setting 4 Monitor the makeup flow Actual reading If the makeup flow is indicating a value in excess of 1 0 mL min this indicates that the jet is plugged or partially plugged pressure is backing up from the H2 channel into the makeup channel of the EPC system resulting in a false flow indication on the makeup channel Alternately remove the jet from the housing and hold it up to a light source Check the holes in the jet for contamination If plugged replace the jet Agilent 7890 Series Troubleshooting 197 Troubleshooting Tasks To Check for a Plugged NPD Jet 198 The detector EPC module controls flow by maintaining a calibrated gas pressure against a fixed restriction A plugged jet will cause inaccurate flow readings To check for a plugged NPD jet measure the ac
101. lume is marked at half height on the barrel not at the top of the barrel enter twice the labeled volume when configuring the syringe size If the drop in peak area or height happened gradually due to baseline rise rather than a sudden change check for detector contamination Bakeout the detector FID TCD uECD If using an FID Verify that the correct jet is installed 67 3 68 Chromatographic Symptoms e Check for a dirty jet e Check for contaminated detector parts To Perform Maintenance on the FID Collector Assembly To Check for a Plugged FID Jet If using a uECD e Replace the fused silica indented mixing liner e Replace and reinstall column e Clean the makeup gas adapter If using an NPD e Check the detector for contamination e Replace ceramic insulators e Replace the bead If using an FPD e Verify correct column installation e Check that the correct filter is installed and is clean e Check the flow rates e Check the makeup gas type To Resolve Low Sensitivity with an FID In normal use the FID can develop deposits on the collector insulators jet and so forth To reduce contamination buildup Agilent recommends using the detector at 300 C or higher However even with normal use deposits develop in the jet usually white silica from column bleed or black carbonaceous soot These deposits reduce sensitivity and cause chromatographic noise and spikes Jets require periodic cleaning
102. lve the GC fault After resolving an MS Shutdown After resolving the GC or MS problem always restore GC to MS communications 1 Press Aux Det 2 Scroll to MS2GC 3 Press On Yes Agilent 7890 Series Troubleshooting 117 5 Shutdown Symptoms Thermal Shutdowns 118 A thermal fault means that the oven or another heated zone is not within its allowable temperature range lower than minimum temperature or higher than maximum temperature Several things could cause this error e A problem with the electrical supply to the instrument e A malfunction of the zone control electronics e A shorted temperature sensor e A shorted heater To recover from this state 1 Fix the cause of the shutdown Check for missing insulation 2 Most thermal shutdowns can be cleared by shutting off the thermal zone Agilent 7890 Series Troubleshooting Agilent 7890 Series Gas Chromatograph Troubleshooting 6 GC Power On and Communication Symptoms GC Does Not Turn On 120 PC Cannot Communicate withGC 121 GC Cannot Communicate with 5977 MSD 122 GC Does Not Recover After Firmware Update 123 GC Turns On Then Stops During Startup During Self Test 124 phe Agilent Technologies 119 6 GC Power On and Communication Symptoms GC Does Not Turn On If the GC does not turn on e Check the power cord e Check the building s power e If the problem is at the GC turn off the GC power Wait 30 seconds then turn the on the GC p
103. mand If using an Agilent data system check the GC and MS IP addresses entered into the data system software Again these must exactly match the values entered into each instrument Agilent 7890 Series Troubleshooting GC Power On and Communication Symptoms 6 GC Does Not Recover After Firmware Update If the GC starts but does not display the Power on successful message look for any error messages Record any messages Then resolve the problem as follows 1 Try power cycling the GC 2 If the GC still does not recover turn off the GC 3 While pressing the Stop and 0 keys turn on the GC Continue to hold the keys until the GC reboots You should see a display similar to the following MMON Version X XX IP 10 1 1 101 If this display appears you can now communicate to the GC Reload the firmware 4 If the GC does not boot up and show a display similar to the one above or if the update fails again contact Agilent for service Agilent 7890 Series Troubleshooting 123 GC Power On and Communication Symptoms GC Turns On Then Stops During Startup During Self Test 124 If the GC turns on but the normal display does not appear 1 Turn the GC power switch Off Wait one minute then turn the GC power On If the GC does not return to normal record any messages that appear on the display Observe the GC back panel and look for LED indicator lights green yellow or red above the REM
104. mic Insulators and Jet e Verify that the FPD photomultiplier tube PMT is properly installed If it is not light leaks and ultimately noise will result FIDs are susceptible to gradual buildup of deposits in the detector In extreme cases spiking occurs along with increased noise level Carbon black deposits may form from solvents that burn poorly primarily chlorinated materials and aromatics Avoid such solvents if possible If you must use them be prepared to clean the detector regularly Silicon dioxide white is formed when bleed from a silicone column is burned in the flame To minimize this use low column loadings select phases with high temperature limits condition columns thoroughly before use and use the lowest possible oven temperature for the analysis To remove either type of deposit disassemble the detector and scrub with a small brush A solvent almost anything will do helps flush away the particles Agilent recommends replacing dirty collector and insulator parts Other factors that can contribute to noise e Column installed too high into detector e Oven temperature exceeds column maximum recommended temperatures Baseline wander and drift Agilent 7890 Series Troubleshooting Baseline wander or drift can occur when a flow or temperature setting is changed If the system has not stabilized at the new conditions before it starts a run some baseline changes are to be expected The following cases
105. mine what type of turret is installed b The syringe carriage moves all the way down then moves back up again and clears the turret c The syringe carriage steps down until it touches the turret This sets its position relative to the turret d The plunger moves to calibrate six stops Observe each of the six steps to verify the plunger loop is functioning properly If it is missing stops send the injector to Agilent for repair When the alignment is complete the Ready light turns on and the sampler returns to the ready state Install the needle support assembly and syringe Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2 Syringe Needle Bends During Injection into Inlet WARNING When troubleshooting the injector keep your hands away from the syringe needle The needle is sharp and may contain hazardous chemicals Refer to your ALS documentation for additional information 7683B Automatic Liquid Sampler Installation Operation and Maintenance 7693A Automatic Liquid Sampler Installation Operation and Maintenance 7650A Automatic Liquid Sampler Installation Operation and Maintenance e Check that the GC septum nut is not too tight e Check that the syringe is installed correctly into the syringe carriage e Check that the needle support and guide are clean Remove any residue or septum deposits Install a new needle support assembly 7683 or needle support foot 7693A or 7650A if neces
106. mn Flow 172 To Measure a Split Vent or Septum Purge Flow 176 To Measure a Detector Flow 178 To Perform the GC Self Test 183 To Check or Monitor Split Vent Line Backpressure 184 To Run the Inlet Trap Check 187 To Perform a SS Split Vent Restriction Test 189 To Adjust the FID Lit Offset 190 To Verify That the FID Flame Is Lit 191 To Verify FID Ignitor Function During Ignition Sequence 192 To Measure FID Leakage Current 193 To Measure FID Baseline Output 194 To Isolate the Cause of FID Noise 195 To Measure NPD Leakage Current 196 To Check for a Plugged FID Jet 197 To Check for a Plugged NPD Jet 198 To Verify That the NPD Bead Is Ignited 199 To Verify That the FPD Flame Is Lit 200 To Adjust the FPD Lit Offset 201 When to Change Gas Purifiers 202 To Check a Split Vent Line for Contamination 203 To Ignore a Device s Readiness State 205 To Use the Stopwatch 206 Ee Agilent Technologies ut 8 Troubleshooting Tasks To Measure a Column Flow Measuring FID TCD uECD and FPD column flow The following procedure can be used to measure column flow with an FID TCD uECD and FPD Hydrogen H2 is flammable and is an explosion hazard when mixed with air in an enclosed space for example a flow meter Purge flowmeters with inert gas as needed Always measure gases individually Always turn off detectors to prevent flame bead autoignition Be careful The detector may be hot enough to cause burns If the detector is ho
107. move any caps plugs Reinstall the column Restore the correct column configuration Load the operating method 147 7 Checking for Leaks To Correct Leaks in the Multimode Inlet 148 If the inlet fails a pressure decay test check the following Check the caps plugs used in the test make sure each is correctly installed and tight If you performed the leak test after performing maintenance check for proper installation of the part s handled during the maintenance Check the tightness of the septum nut See To change the septum on the Multimode inlet Check the septum Replace if old or damaged Check the insert assembly installation Check the liner and liner O ring See To change the liner and O ring on the Multimode inlet Make sure the inlet temperature remained constant during the test If these items do not resolve the problem contact Agilent for service Agilent 7890 Series Troubleshooting Checking for Leaks 7 To Perform a PP Pressure Decay Leak Test Use the Agilent Instrument Utilities Purged Packed Inlet Pressure Decay Test to determine if the inlet is leaking Open the software select the GC and run the test for the inlet If the Instrument Utilities software is not available see the procedure below If the test fails e Tighten the septum nut Merlin cap e Replace the septum or Merlin Microseal e Tighten the top insert weldment Replace the liner e Replace the O ring and tight
108. n Column Inlet To Clean the Septumless Head on the PTV Inlet To Clean the Multimode Inlet To Clean the Septum Seat in the Septum Head Assembly of the PTV Inlet To Clean the VI e Check the solvent level in the ALS wash bottles e Replace the ALS syringe if necessary 7693A 7683 e Check the sample injection volume Verify that the ALS is injecting enough sample into the inlet Use the Solvent Vapor Volume Calculator to determine how much of the sample should be injected e Ghost peaks are sometimes caused by contaminated sample vials Try new or clean vials to see if ghost peaks disappear e Some samples change with heat or ultraviolet light Check the sample stability Column method e Perform column maintenance Bake out contaminants remove the contaminated length of column near the inlet and reverse and bake out the column as needed e If you suspect that there is contamination in the column perform the bakeout procedure Agilent 7890 Series Troubleshooting 45 3 46 Chromatographic Symptoms Verify that the oven program temperature and time are sufficient for the samples being injected Ghost peaks that are broader than adjacent sample peaks could be from a previous run Inspect the column for contamination High molecular weight samples that contain residues may cause the syringe the inlet liner or the first few inches of column to become contaminated Install an Agilent column backflush system Det
109. ng different from actual flow rates causing nonideal ignition conditions Thoroughly leak check the whole system especially the column fitting at the FID See Checking for Leaks Check the column flow rate See To Measure a Column Flow Hydrogen flow should be greater than the sum of the column flow and makeup flow If the analysis permits substitute nitrogen for helium as makeup Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2 FID Ignitor Does Not Glow During Ignition Sequence WARNING Keep body parts at a safe distance from the FID chimney while performing this task If using hydrogen the FID flame will not be visible 1 Remove the detector top cover 2 Turn the FID flame On 3 Observe the ignitor plug though the FID chimney The small hole should glow during ignition sequence If the test fails check for the following possible causes e The ignitor may be bad replace the ignitor See To Perform Maintenance on the FID Collector Assembly e Detector temperature is set to lt 150 C Agilent recommends operating the FID at gt 300 C e The ignitor is not making a good connection to the ground The ignitor must be tightly screwed into the FID castle assembly The three T 20 Torx screws that hold the collector assembly in place must be tight Agilent 7890 Series Troubleshooting 31 2 ALS and Detector Symptoms e The brass knurled nut that holds the FID castle assembly in p
110. ns Detector gases Hydrogen Air Carrier makeup 10 to 60 1to5 50 60 60 10 to 60 1to5 75 100 60 e Measure the actual detector flows See To Measure a Detector Flow e The column may be installed too high into the detector e Check that the FPD ignitor operates See To Verify That the FPD Flame Is Lit Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2 e During the ignition sequence display the air flow rate The air flow rate should go to 200 mL min 7890A or 400 mL min 7890B while trying to ignite to flame If not there is insufficient air supply pressure e Check the column and makeup flow rates e Ensure that condensation in the vent tube is not dripping back into the detector The flexible plastic vent tube must run from the detector into a container without sagging in order to properly drain water condensate Keep the open tube end out of the water in the container e Check the Lit offset value The typical Lit offset value is 2 0 If it is zero autoignition is turned off If it is too large the software will not recognize that the flame is lit and will shut the detector down e If the flame still will not light there could be a large leak in the system This results in measured flow rates being different from actual flow rates causing non ideal ignition conditions Thoroughly leak check the whole system See Checking for Leaks e Try increasing the supply pressu
111. ns If either is hot wear heat resistant gloves to protect your hands 1 Gather the following 1 16 inch nut for transfer line Ferrule for transfer line Heat resistant gloves if the inlet is hot 2 Disconnect the transfer line from the interface 3 Disconnect the carrier line from the sampler 4 Prepare the end of the carrier line using a 1 16 inch male nut and ferrule 5 Connect the carrier line to the interface where you removed the transfer line and tighten the nut finger tight Tighten an additional 1 4 to 1 2 turn with the 1 4 inch wrench 6 Return to To Perform a VI Pressure Decay Test and repeat steps 9 to 16 Agilent 7890 Series Troubleshooting Checking for Leaks 7 To Correct Leaks in the Volatiles Interface Agilent 7890 Series Troubleshooting If the inlet fails a pressure decay test check the following The caps and plugs used in the test make sure each is correctly installed and tight If you performed the leak test after performing maintenance check for proper installation of the part s handled during the maintenance The split vent and pressure sensing connections at the interface The sampler connection to the interface The sampler If these items do not resolve the problem contact Agilent for service 169 7 Checking for Leaks 170 Agilent 7890 Series Troubleshooting Agilent 7890 Series Gas Chromatograph Troubleshooting 8 Troubleshooting Tasks To Measure a Colu
112. ollowing Increase the viscosity delay time Dilute the sample in an appropriate low viscosity solvent Turn the tower fan off For 7683B ALS use the tray quadrants to warm the sample For 7693A ALS use the vial heater accessory G4514A Bar Code Reader Mixer Heater to warm the sample vial If the problem is with the detector see Table 3 Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting Chromatographic Symptoms Table 3 Detector troubleshooting Detector Solution 3 FID FPD TCD d Verify that the electrometer is turned on Verify that the flame is still lit Verify that the filament is turned on Ensure that the reference gas is not set to zero The filament will not turn on with zero reference gas flow 49 3 Chromatographic Symptoms Baseline Rise During Oven Temperature Program 50 Inspect the column for bleed Check for leaks oxygen in carrier gas supply Oxygen can damage bonded phase capillary columns Check gas supply oxygen trap indicator or date Make solvent blank runs to evaluate baseline without sample Make no injection blank runs remove the syringe from the injector and start a run to evaluate baseline without solvent Check for contamination See Contamination or Carryover Consider the effect of column film thickness on bleed Try using a column with a thinner film Check for leaks at the column fittings See Checking for
113. operate the detector at gt 300 C Check for carbonization in the detector due to injection or aromatic or chlorinated solvents To avoid this problem operate the detector at gt 300 C Reassemble and install the collector and operate the detector using higher air and hydrogen flows air must be 450 mL min hydrogen at 35 mL min 73 3 Chromatographic Symptoms FPD Flame Goes Out During a Run and Attempts to Reignite If the flame goes out during a run do the following e Check the GC system for leaks especially at the detector column fitting See Checking for Leaks e FPD Verify the transfer line temperature is set gt 200 C e FPD Verify the detector temperature is set 200 C e Ensure that condensation in the vent tube is not dripping back into the detector The flexible plastic vent tube must run from the detector into a container without sagging in order to properly drain water condensate Keep the open tube end out of the water in the container If the FPD flame goes out and then reignites do the following e Verify that the Lit offset setting is lower than the normal baseline e Check for leaks See Checking for Leaks e Check the flow settings then measure the actual detector flows See To Measure a Detector Flow e Certain environmental conditions such as Strong electromagnetic fields Large ambient temperature swings Large atmospheric pressure swings can cause an
114. or splitless liners first try reinstalling the liner Splitless liners create more backpressure than split liners and so minor variations in orientation can make a difference at low head pressures 184 Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 To set a warning limit for the inlet trap check Agilent 7890 Series Troubleshooting To use the inlet trap check to monitor the split vent trap 1 If the existing split vent trap has been used for many sample injections replace it Make sure that the GC is clean Replace inlet hardware if needed Check that the split vent line is free from contamination or restrictions Run the inlet trap check See To Run the Inlet Trap Check Note the pressure This reading is the backpressure you can expect from a clean system with the installed liner Determine a practical split vent backpressure limit Use the GC normally Periodically rerun the inlet trap check You will need to change the split vent trap when either You see chromatographic issues related to a restriction in the split vent typically poor split mode area repeatability or The reported test pressure approaches or exceeds the method column head pressure setpoint Run the inlet trap check and note the pressure Change the split vent trap Set a warning limit and behavior if desired Now that you know when the trap needs to be changed you can set one or two limits in the test Use these
115. oting 4 GC Not Ready Symptoms GC Never Becomes Ready 90 Flow Never Becomes Ready 91 Oven Temperature Never Cools Down Cools Very Slowly 92 Oven Never Heats Up 93 Temperature Never Becomes Ready 94 Cannot Set a Flow or Pressure 95 A Gas Does Not Reach Setpoint Pressure or Flow 96 A Gas Exceeds Pressure Setpoint or Flow 97 The Inlet Pressure or Flow Fluctuates 98 Cannot Maintain a Pressure as Low as the Setpoint on a Split Inlet 99 The Measured Column Flow Does Not Equal the Displayed Flow 100 FID Does Not Ignite 101 FID Ignitor Does Not Glow During Injection Sequence 102 FID or NPD Measured Hydrogen and Makeup Gas Flows Much Less Than Setpoint 104 NPD Adjust Offset Process Fails 105 FPD Does Not Ignite 106 Valve Not Ready 108 Blinking Not Ready Light Detector Hardware Fault TCD Filament Voltage 109 This section includes faults and symptoms that will occur when the GC is on but cannot perform analyses This is indicated by a Not Ready warning by fault messages or by other symptoms ot Agilent Technologies 89 4 GC Not Ready Symptoms GC Never Becomes Ready 90 Normally the GC becomes ready after flows and temperatures reach setpoint If the GC does not become ready after a long period of time e Press Status or a component key for example Front inlet to see which setpoints or conditions are not ready e Check for a sampler problem e Check for a data system problem e If performing manua
116. ough the FID chimney The small hole should glow during ignition sequence 192 Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 To Measure FID Leakage Current Agilent 7890 Series Troubleshooting 1 Load the analytical method Make sure flows are acceptable for ignition Heat the detector to operating temperature or to 300 C Turn off the FID flame Press Front Det or Back Det then scroll to Output Verify that the output is stable and lt 1 0 pA If the output is unstable or gt 1 0 pA turn off the GC and check for proper assembly of the upper FID parts and for contamination If the contamination is confined to the detector bakeout the FID Turn on the flame 193 Troubleshooting Tasks To Measure FID Baseline Output 194 Aa WwW N With the column installed load your checkout method Set the oven temperature to 35 C Press Front Det or Back Det then scroll to Output When the flame is lit and the GC is ready verify that the output is stable and lt 20 pA this may take some time If the output is not stable or gt 20 pA the system or gas may be contaminated If this contamination is isolated to the detector bakeout the FID Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 To Isolate the Cause of FID Noise FID noise is the result of mechanical electrical and chemical factors FID noise can be a subjective parameter Often FID baseline noise is perceived b
117. ower 120 Agilent 7890 Series Troubleshooting GC Power On and Communication Symptoms 6 PC Cannot Communicate with GC Agilent 7890 Series Troubleshooting e Run a ping test The MS DOS ping command verifies communications across a TCP IP connection To use it open the command prompt window Type ping followed by an IP address For example if the IP address is 10 1 1 101 enter ping 10 1 1 101 If LAN communications are working properly you will see a successful reply For example B Command Prompt Microsoft Windows XP Version 5 1 2606 lt C gt Copyright 1985 2661 Microsoft Corp C gt ping 10 1 1 101 Pinging 16 1 1 101 with 32 bytes of data Reply from 14 1 Reply from 16 1 1 a 1 bytes 32 time lt ims TTL 128 1 bytes 32 time lt ims TTL 128 1 bytes 32 time lt ims TTL 128 1 bytes 32 time lt ims TTL 128 Reply from 10 Reply from 16 Ping statistics for 10 1 1 101 Packets Sent 4 Received 4 Lost loss Approximate round trip times in milli seconds Minimum ms Maximum ms Average Gms ND If the ping test is successful check the software configuration If the problem is that a data system cannot connect to the GC check if another PC is controlling the GC At the GC keypad press Options scroll to and select Communication then scroll the display down If a computer is connected to the GC its network name will appear below the Enable DHCP line If the ping t
118. p to the column fitting After performing maintenance first check for leaks in externally accessible areas See To Check for External Leaks If a leak is known to exist check the externally accessible inlet fittings first especially any connection that has seen recent maintenance such as the septum nut column adapter column connection and so forth The pressure decay leak test described below requires removing the column and capping the inlet column fitting This test can cannot find the following types of leaks Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting The test can find leaks at the Checking for Leaks 7 The test cannot find leaks at the septum septum nut liner O ring seal gold seal washer and reducing nut inlet body flow manifold split vent valve flow manifold septum purge valve split vent tubing and trap septum purge tubing seals within the tubing between the inlet flow module and the inlet body column fitting gas supply bulkhead fittings to the flow module tubing and connections in a transfer line connected to the inlet internal leaks in an EPC module septum purge valve 1 Gather the following see Consumables and parts for the split splitless inlet No hole ferrule 1 4 inch wrench Heat resistant gloves if the inlet is hot Column nut New septum O ring ECD TCD Detector plug part no 5060 9055 2 Load the inlet maintenan
119. purge flows attach the flowmeter to the appropriate tube Remove the GC pneumatics cover to access the back inlet exhausts Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 e The split vent has a 1 8 in Swagelok threaded fitting Create and use a 1 8 in tube adapter as shown below to convert the 1 8 in threaded fitting into a 1 8 in tube This prevents the rubber flowmeter tubing from leaking around the threads which will result in leakage and thus an incorrect flow reading JU TA e The septum purge is a 1 8 in tube Use the red rubber adapter shown to measure flows 177 Troubleshooting Tasks To Measure a Detector Flow 178 Detectors especially detectors with flame require precise flow measurements to function properly Incorrect flows are caused by e Restrictions in the supply line which will cause a Not Ready message on the GC display all detectors e A leaking column or column adapter fitting all detectors e A plugged jet FID NPD e A leak in the burner chamber window seal or ignitor seal FPD e A pressure sensor that needs to be zeroed See To Zero the EPC Module Pressure Sensor e An EPC valve that is not operating correctly To isolate the problem compare the flow of one channel of gas against the actual flow rate Measuring FID TCD uECD and FPD flows Hydrogen H2 is flammable and is an explosion hazard when mixed with air in
120. quence See To Verify FID Ignitor Function During Ignition Sequence Check that the air and hydrogen pressures meet Agilent s recommendations hydrogen gt 35 psi 210 kPa and air gt 55 psi 380 kPa See the Agilent GC GC MS and ALS Site Preparation Guide Try increasing the supply pressures to the FID flow module This makes the flame easier to light without changing the setpoints Increase hydrogen flow and decrease or turn off makeup gas flow until ignition occurs then reduce them toward the method values Experiment for the best values Increasing hydrogen flow and decreasing makeup flow will help the FID ignite more easily If it will light under these modified conditions the cause could be a partially clogged jet a weak ignitor or a leak at the column fitting Check for a plugged or partially plugged jet See To Check for a Plugged FID Jet Measure the FID flow rates Actual flow rates should be within 10 of the setpoint See FID starting conditions The hydrogen air ratio greatly impacts ignition Nonoptimal flow settings can prevent flame ignition See To Measure a Detector Flow There could be a large leak in the system if the flame still will not light Large leaks result in measured flow rates being different from actual flow rates causing nonideal ignition conditions Thoroughly leak check the whole system especially the column fitting at the FID See Checking for Leaks Check the column
121. r from the front of the column Replace the column Verify that the column was cut and installed properly Re cut and reinstall the column into the inlet and replace the ferrules Make a clean square cut using a reliable tool Confirm the installation is leak free If there is a leak at the column fitting you will see more tailing for early eluting peaks See Checking for Leaks Consider the type of adapter liner and inlet seal being used One or all of these may be contaminated or active Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Use a new deactivated liner This only affects active compounds Clean or replace the inlet seal e Check adapters if installed and liner for solid particles If solid particles are visible clean or replace e For capillary splitless injection consider compatibility between the solvent and column Use a different solvent This will help in instances where there is more tailing for the early eluting peaks or those closest to the solvent front Use a 3 to 5 meter retention gap e Verify that the injection technique is adequate This is usually related to erratic plunger depression or having sample in the syringe needle e Verify the inlet temperature If the temperature is too high tailing is generally worse for early eluters Decrease inlet temperature by 50 C If the temperature is too low tailing usually increases with retention Increase inlet
122. rature is not too low See the following e Recommended starting conditions for new FID methods e Selecting reference and makeup flows for the TCD e Recommended starting conditions for new uECD methods Agilent 7890 Series Troubleshooting Chromatographic Symptoms 3 Microcell Electron Capture Detector uECD Noise and Sensitivity CAUTION Detector disassembly and or cleaning procedures other than thermal should be performed only by personnel trained and licensed appropriately to handle radioactive materials Trace amounts of radioactive 63 Ni may be removed during these other procedures causing possible hazardous exposure to radiation To prevent possible hazardous contamination of the area with radioactive material the detector exhaust vent must always be connected to a fume hood or otherwise vented in compliance with local regulations Agilent 7890 Series Troubleshooting Performance problems associated with the ECD include but are not limited to loss of sensitivity real or perceived high signal background noisy baseline and chromatographic peaks or humps that are not characteristic of the samples being injected If the problems are not accompanied by an increase in the signal output as read from the front keypad of the GC then suspect the detector only after the other parts of the chromatographic system have been checked Before starting extensive troubleshooting consider first the nature of the problem
123. rdware Fault TCD Filament Voltage Agilent 7890 Series Troubleshooting If the TCD filament is open the Not Ready LED blinks and the GC will not become Ready 1 Press Status If the display reads Front detector hardware fault or Back or Aux detector hardware fault the problem may be the TCD filament Press Front Det or Back Det or Aux Det If the display reads Fault TCD Filament Voltage scroll to the Filament setpoint If the setpoint is flashing Off the problem is an open TCD filament Power cycle the GC Press Front Det or Back Det or Aux Det Scroll to the Filament and press Off No to disable the TCD filament Contact Agilent for service To continue to use the GC without the TCD 1 2 Turn off all TCD parameters Save the method Reconfigure the GC to use another detector Move the column and set other parameters as needed 39 2 ALS and Detector Symptoms Shutdown Defective Device CAUTION By default the GC monitors the status of all configured devices inlets detectors valve box heaters valves oven heater EPC modules and so forth and becomes ready when all of them reach setpoint If the GC senses a problem in one of these devices the GC will either never become ready or may go into a shutdown state to protect itself or prevent a safety hazard However there may be a time when you do not wish to have the readiness state of a device prevent a run from starting An
124. re Decay Test Use the Agilent Instrument Utilities Multimode Inlet Pressure Decay Test to determine if the inlet is leaking Open the software select the GC and run the test for the inlet If the Instrument Utilities software is not available see the procedure below If the test fails e Check the plugged column fitting and septum purge cap e Check the septum head Tighten if needed e Replace the septum if necessary e Inspect and re install the liner if it is leaking e Tighten the split vent trap if needed or install a new cartridge and O rings e Tighten the split vent line connection to the inlet To Perform a Multimode Inlet Pressure Decay Test The pressure decay test checks for leaks from the inlet flow module up to the column fitting After performing maintenance first check for leaks in externally accessible areas See To Check for External Leaks If a leak is known to exist check the externally accessible inlet fittings first especially any connection that has seen recent maintenance such as the septum nut column adapter column connection and so forth The pressure decay leak test described below requires removing the column and capping the inlet column fitting This test can cannot find the following types of leaks 144 Agilent 7890 Series Troubleshooting Agilent 7890 Series Troubleshooting The test can find leaks at the Checking for Leaks 7 The test cannot find leaks at the s
125. re FID Baseline Output 194 To Isolate the Cause of FID Noise 195 To Measure NPD Leakage Current 196 To Check fora Plugged FID Jet 197 To Check fora Plugged NPD Jet 198 To Verify That the NPD Bead Is Ignited 199 To Verify That the FPD Flame Is Lit 200 To Adjust the FPD Lit Offset 201 When to Change Gas Purifiers 202 To Check a Split Vent Line for Contamination 203 To Ignore a Device s Readiness State 205 To Use the Stopwatch 206 Troubleshooting Agilent 7890 Series Gas Chromatograph Troubleshooting 1 Concepts and General Tasks Concepts 10 7890B 5977 GC MSD Systems 12 Configurable Items to Always Keep Current 13 To View the Run Log Maintenance Log and Event Log 15 Information to Obtain Before Calling Agilent for Service 16 phe Agilent Technologies 1 Concepts and General Tasks Concepts 10 This manual provides lists of symptoms and corresponding tasks to perform should you experience errors associated with GC hardware or chromatographic output GC Not Ready messages and other common issues Each section describes a problem and provides a bulleted list of possible causes for you to troubleshoot These lists are not intended for use in the development of new methods Proceed with troubleshooting under the assumption that method s are working properly This manual also includes common troubleshooting tasks as well as information needed prior to calling Agilent for service While this manual describes
126. reacts with changes such as e Turning off the column oven e Setting low pressures flows for the MSD flow path e Turning off hydrogen carrier gas flow if used e Aborting a current run e Turning off the MS transfer line heater e Blocking all setpoint changes The exact changes depend on the event that triggered the shutdown For example the GC may react differently to a communications loss than to a failure in the MSD high vacuum pump When troubleshooting an MSD Shutdown 1 Check all GC MSD and data system events and logs The GC will enter MS Shutdown if The GC cannot maintain carrier flow into the MS The MS reports a shutdown or fault The GC and MS lose communications with each other 2 Check the current communications status a Press Aux Det b The MS2GC setting should read Connected If not check the entered GC and MSD IP addresses in the GC the MSD and the PC All GC and MSD IP addresses must match in all three places c Check the GC and MS LAN connections Is the LAN switch or hub operating Clearing an MS Shutdown 116 Unlike other shutdowns you cannot clear this state by turning off a setpoint because setpoint changes are blocked Instead clear this state by disabling GC to MS communications 1 Press Aux Det 2 Scroll to MS2GC 3 Press Off No Agilent 7890 Series Troubleshooting Shutdown Symptoms 5 If the GC started the shutdown you can now troubleshoot the problem and reso
127. reads Front detector hardware fault or Back or Aux detector hardware fault the problem may be the TCD filament Press Front Det or Back Det or Aux Det If the display reads Fault TCD Filament Voltage scroll to the Filament setpoint If the setpoint is flashing Off the problem is an open TCD filament Power cycle the GC Press Front Det or Back Det or Aux Det Scroll to the Filament and press Off No to disable the TCD filament Contact Agilent for service To continue to use the GC without the TCD 1 2 Turn off all TCD parameters Save the method Reconfigure the GC to use another detector Move the column and set other parameters as needed 109 4 GC Not Ready Symptoms 110 Agilent 7890 Series Troubleshooting Agilent 7890 Series Gas Chromatograph Troubleshooting 5 Shutdown Symptoms Column Shutdowns 112 Hydrogen Shutdowns 114 7890B MSD Shutdown 116 Thermal Shutdowns 118 phe Agilent Technologies 111 5 Shutdown Symptoms Column Shutdowns The GC monitors inlet and auxiliary gas streams If a carrier gas which can include an auxiliary flow module or pneumatics control module is unable to reach its flow or pressure setpoint the GC assumes that a leak exists It will warn you with a beep after 25 seconds and it will continue to beep in intervals After about 5 minutes the GC will shut down components to create a safe state The GC e Displays Front inlet pressure shut
128. res to the FPD flow module This makes the flame easier to light without changing the setpoints e Under some operating conditions the flame will light more easily with the vent tube removed After lighting the flame reinstall the vent tube e The sulfur mode can be particularly hard to light FPD only not FPD Try changing to the phosphorus mode flows lighting the flame and gradually alter the flows to the sulfur values e Check cable connections to coupling coupling connection to glow plug tight glow plug Agilent 7890 Series Troubleshooting 35 2 ALS and Detector Symptoms NPD Adjust Offset Process Fails 36 Inspect the jet to see if it is clogged See To Check for a Plugged NPD Jet Measure the actual detector flows See To Measure a Detector Flow If the hydrogen or makeup flows are zero or much lower than the displayed flow suspect a plugged jet Check the condition of the bead Replace if necessary Verify that the flow settings are correct See Flows temperatures and bead information If the process still fails there could be a large leak in the system This causes measured flow rates to be different from actual flow rates Thoroughly leak check the whole system especially the detector column fitting See Checking for Leaks Set the equilibration time to 0 0 Agilent 7890 Series Troubleshooting NPD Bead Will Not Ignite Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2
129. rms the warranty terms in the separate agreement shall control Safety Notices CAUTION A CAUTION notice denotes a hazard It calls attention to an operating procedure practice or the like that if not correctly performed or adhered to could result in damage to the product or loss of important data Do not proceed beyond a CAUTION notice until the indicated conditions are fully understood and met A WARNING notice denotes a hazard It calls attention to an operating procedure practice or the like that if not correctly performed or adhered to could result in personal injury or death Do not proceed beyond a WARNING notice until the indicated conditions are fully understood and met Contents 1 Concepts and General Tasks Concepts 10 How to troubleshoot using this manual 10 The Status key 10 Error conditions 11 7890B 5977 GC MSD Systems 12 Configurable Items to Always Keep Current 13 Inlet and detector configuration 13 Column configuration 13 Automatic Liquid Sampler configuration 14 Gas configuration 14 To View the Run Log Maintenance Log and Event Log 15 RunLog 15 Maintenance Log 15 EventLog 15 Information to Obtain Before Calling Agilent for Service 16 2 ALS and Detector Symptoms Plunger Errors 18 Procedure 18 Vial Mishandled by ALS 7693A 19 Alignment Light on 7693A 7650A Injector Toweris On 21 Vial Mishandled by ALS 7683 22 Alignment Light on 7683B Injector Toweris On 24 Syringe Needle
130. s Troubleshooting Checking forLeaks 7 The pressure should drop approximately 1 psi 6 9 kPa during the first 1 to 2 minutes After an initial pressure drop of about 1 psi the pressure should not drop more than 0 03 psi min 0 21 kPa min If the pressure drop is 0 03 psi min or less you can consider the interface gas sampler system leak free If the pressure drops faster than the acceptable rate you must check the interface and sampler systems separately to determine the source of the leak See To Prepare the VI for a Closed System Leak Check to create a closed flow system then return to this section and complete steps 10 to 16 If you find a leak in the interface refer to To Correct Leaks in the Volatiles Interface If the interface is leak free pressure check the sampling device See the operating manual for your sampler for instructions 19 After the VI passes the test restore the GC to operating condition Remove any caps plugs If needed reconnect the sampling device Reinstall the column Restore the correct column configuration Load the operating method 167 7 Checking for Leaks To Prepare the VI for a Closed System Leak Check 168 To leak check the interface independently of the gas sampling device you must disconnect the sampler from the interface to isolate the interface flow system from the sampler WARNING Be careful The oven and or inlet may be hot enough to cause bur
131. sary e If using the cool on column inlet check that the correct insert for the syringe is installed See To Check the Needle to Column Size on the COC Inlet for more information e Check that you are using the proper syringe The combined length of the syringe barrel and needle should be approximately 126 5 mm e Check that the sample vial dimensions meet specification See Vial Mishandled by ALS 7693A or Vial Mishandled by ALS 7683 e Check that the crimp cap is properly installed Refer to your sampler documentation Agilent 7890 Series Troubleshooting 25 2 ALS and Detector Symptoms FID Fails Leakage Current Test Possible causes A failed leakage current test usually indicates misassembly contamination or a damaged part Procedure 1 If you have just performed maintenance on the FID first verify that the detector was reassembled properly before troubleshooting detector problems 2 Replace the PTFE FID for contamination 3 Make sure that the interconnect spring is not damaged bent or dirty The interconnect spring should be touching the bottom of the collector If the inteconnect spring is damaged bent or dirty call Agilent for service FID interconnect spring 26 Agilent 7890 Series Troubleshooting ALS and Detector Symptoms 2 NPD Fails Leakage Current Test A failed leakage current test usually indicates misassembly contamination or a damaged part If you have just perform
132. shooting Tasks To Adjust the FID Lit Offset 190 To adjust the FID Lit offset 1 2 Press Config Scroll to Front detector or Back detector wherever the detector is installed and press Enter Scroll to Lit offset With the Lit offset line highlighted enter the new parameter for the detector and press Enter Lit offset should be lt 2 0 pA or lower than the normal FID output when lit Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 To Verify That the FID Flame Is Lit To verify that the FID flame is lit hold a mirror or other reflective surface over the collector exhaust Steady condensation indicates that the flame is lit Typically the FID output will be between 5 0 and 20 0 pA when lit and lt 2 0 pA when not lit If the flame does not light do the following e Verify that the detector temperature is above 150 C Agilent recommends operating the FID 2300 C e Verify correct detector flows e Inspect the jet for contamination e Verify that the jet is installed correctly e Check the column connections for leaks Agilent 7890 Series Troubleshooting 191 8 Troubleshooting Tasks To Verify FID Ignitor Function During Ignition Sequence WARNING Keep body parts at a safe distance from the FID chimney while performing this task If using hydrogen the FID flame will not be visible 1 Remove the detector top cover 2 Turn the FID flame On 3 Observe the ignitor plug th
133. sure causes variations in the flow rate and retention times during a run Do the following Check if the gas purifier or gas generator is operating at or near capacity Check the supply gas for sufficient delivery pressure Verify that the supply pressure regulator is functioning properly Systems with long supply tubing lengths may require a step down regulator near the GC Also use an additional regulator to smooth out fluctuations caused by gas generators Check for leaks See Checking for Leaks A large leak may be present somewhere in the system Use an electronic leak detector to find leaks then correct them Do not forget to check the column a broken column is a very large leak Check for large restrictions in the inlet liner or split vent trap Verify that the correct liner is installed Some liners have large pressure drops caused by design or tight packaging Check for extreme changes in room temperature during runs Correct laboratory temperature problem or move the instrument to a more suitable location Check for a restriction in headspace purge and trap and any other external sampling devices Verify Auto Flow Zero feature is On See AutoFlowZero Agilent 7890 Series Troubleshooting GC Not Ready Symptoms 4 Cannot Maintain a Pressure as Low as the Setpoint on a Split Inlet If the GC cannot maintain a pressure as low as the setpoint check for the following e Consider using a liner designed
134. t wear heat resistant gloves to protect your hands 172 1 Gather the following Appropriate flowmeter adapter tube can be found in the GC ship kit Electronic flowmeter calibrated for the gas and flow rates of concern 2 Turn off the detector 3 Turn off the detector flows 4 Connect the appropriate adapter to the detector exhaust Flowmeter tube diameters vary by model modify the adapter to the flowmeter tubing as needed A 1 8 in rubber adapter tube attaches directly to a uECD or TCD exhaust vent A separate adapter 19301 60660 is supplied for the FID Insert the adapter into the detector exhaust vent as far as possible You will feel resistance as the adapter O ring is forced into the detector exhaust vent Twist and push the adapter during insertion to ensure a good seal Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 Sz For the FPD remove the plastic tubing from the FPD exhaust and connect the flowmeter directly to the FPD vent tube If necessary use a 1 4 inch tube adapter between the detector exhaust and the flowmeter tubing 5 Connect the flowmeter to the flowmeter adapter to measure flow rates Measuring NPD column flow 1 Gather the following e NPD flowmeter adapter tool G1534 60640 Agilent 7890 Series Troubleshooting 173 8 Troubleshooting Tasks e Flow measuring insert 19301 60660 e Electronic flowmeter calibrated for the gas and flow rates of concern 2 S
135. t run Has the GC stabilized For a multimode or split splitless inlet in split mode also check for e An abnormal split vent restriction See To Run the Inlet Trap Check To Perform a SS Split Vent Restriction Test e To troubleshoot small leaks in a multimode or split splitless inlet see To Check for Leaks in a Split Splitless Inlet or To Check for Leaks in a Multimode Inlet Agilent 7890 Series Troubleshooting 43 3 Chromatographic Symptoms Contamination or Carryover If your output has contamination or unexpected peaks do the following Isolate the source 1 Perform a solvent blank run using a new pure source of solvent If the contamination disappears the problem may be either in the sample or solvent related Perform a blank run remove the syringe from the injector and start a run If the contamination disappears the problem is in the syringe Remove the column from the detector and cap the detector fitting Perform another blank run If the contamination disappears the problem is in the inlet or column If the contamination remains the problem is in the detector Check possible causes all inlet and detector combinations Inlet sampler sample gas supply Check the septum type and installation The vial septum may be dissolving in the sample Be sure the vial septum is resistant enough to the solvent you are using Also ensure the vial septum is flat If the vial septum is not flat the needle t
136. tainer without sagging in order to properly drain water condensate Keep the open tube end out of the water in the container e Check the Lit offset value The typical Lit offset value is 2 0 If it is zero autoignition is turned off If it is too large the software will not recognize that the flame is lit and will shut the detector down e If the flame still will not light there could be a large leak in the system This results in measured flow rates being different from actual flow rates causing non ideal ignition conditions Thoroughly leak check the whole system See Checking for Leaks e Try increasing the supply pressures to the FPD flow module This makes the flame easier to light without changing the setpoints e Under some operating conditions the flame will light more easily with the vent tube removed After lighting the flame reinstall the vent tube e The sulfur mode can be particularly hard to light FPD only not FPD Try changing to the phosphorus mode flows lighting the flame and gradually alter the flows to the sulfur values e Check cable connections to coupling coupling connection to glow plug tight glow plug Agilent 7890 Series Troubleshooting 107 4 GC Not Ready Symptoms Valve Not Ready External valves Troubleshooting depends on the type of valve External valves are valves connected to the GC through the external events or BCD connectors on the back panel This Not Ready state means
137. tes and that they match the type of filter installed in the FPD The hydrogen air ratio greatly impacts ignition Nonoptimal flow settings can prevent flame ignition Table 6 FPD recommended flows Sulfur mode flows mL min Phosphorus mode flows mL min Carrier hydrogen helium nitrogen argon Packed columns Capillary columns Detector gases Hydrogen Air Carrier makeup 10 to 60 1to5 60 60 60 10 to 60 1to5 60 60 60 Table 7 FPD recommended flows Sulfur mode flows mL min Phosphorus mode flows mL min Carrier hydrogen helium nitrogen argon Packed columns Capillary columns Detector gases Hydrogen Air Carrier makeup 10 to 60 1to5 50 60 60 10 to 60 1to5 75 100 60 e Measure the actual detector flows See To Measure a Detector Flow e The column may be installed too high into the detector e Check that the FPD ignitor operates See To Verify That the FPD Flame Is Lit Agilent 7890 Series Troubleshooting GC Not Ready Symptoms 4 e During the ignition sequence display the air flow rate The air flow rate should go to 200 mL min 7890A or 400 mL min 7890B while trying to ignite to flame If not there is insufficient air supply pressure e Check the column and makeup flow rates e Ensure that condensation in the vent tube is not dripping back into the detector The flexible plastic vent tube must run from the detector into a con
138. the GC to become ready Remove the column if installed Plug the column fitting with a column nut and a no hole ferrule Set the inlet to Split Mode Configure the column as 0 length Set the inlet temperature to 100 C Set the Total flow to 60 mL min Enter a pressure setpoint of 25 psi 172 kPa Make sure that the pressure supplied to the GC is at least 10 psi 70 kPa higher than the inlet pressure If pressure cannot be achieved there is either a large leak or the supply pressure is too low Set the Septum purge flow to 3 0 mL min Allow the inlet temperature to stabilize Temperature changes can invalidate the test 165 7 Checking for Leaks Back inlet split vent Front inlet split vent 166 13 Cap the septum purge fitting with the ECD TCD detector plug Back inlet purge vent O Front inlet Be O purge vent Q Front purge vent shown plugged 14 From the keypad press Service Mode Select Diagnostics gt Front or Back Inlet gt Pneumatics Control gt Septum Purge control 15 Scroll to the Constant duty cycle and enter 50 Wait 10 seconds 16 Press Front or Back Inlet Scroll to Pressure and press Off No 17 Quickly turn off the carrier gas supply at its source 18 Monitor the pressure for 10 15 minutes Use the timer by pressing Time and Enter Agilent 7890 Series Troubleshooting Agilent 7890 Serie
139. the inlet body Agilent 7890 Series Troubleshooting Checking for Leaks 7 Flow block fittings on the flow manifold Alternately use an electronic leak detector to check these fittings connections If these checks do not resolve the problem contact Agilent for service Low Sensitivity or Poor Repeatability A small leak in the Multimode EPC inlet can cause low sensitivity or poor repeatability Check for and isolate a small leak as described below If you have recently performed maintenance first check for leaks on any fittings parts you handled 1 Perform the inlet pressure decay test If the test passes consider the inlet leak free and check other possible causes for the low sensitivity or poor repeatability 2 If the pressure decay test fails set the inlet to split mode Set a column flow of 3 mL min a septum purge flow of 3 mL min and a purge flow of 50 mL min Press Prep Run Monitor the inlet total flow If the total flow is much greater than 6 mL min check tighten the following fittings Septum nut Column Split vent trap Liner O ring Split vent line connection to the inlet body Flow block fittings on the flow manifold If the problem continues the leak may be small 3 Use an electronic leak detector to check the fittings connections If these checks do not resolve the problem contact Agilent for service Agilent 7890 Series Troubleshooting 143 7 Checking for Leaks To Perform a MMI Pressu
140. tual hydrogen and makeup flows See Measuring NPD flows If the flows are lower than the displayed values replace the jet Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 To Verify That the NPD Bead Is Ignited WARNING Hot exhaust Detector exhaust is hot and can cause burns To verify that the bead is ignited look through the vent hole on the detector lid to see if the bead is glowing orange The NPD output is selected by the operator as part of the adjust offset process and generally is between 5 0 and 50 0 pA Agilent 7890 Series Troubleshooting 199 8 Troubleshooting Tasks To Verify That the FPD Flame Is Lit To verify that the FPD flame is lit 1 Remove the rubber drip tube from the detector vent 2 Hold a mirror or shiny surface near the aluminum exhaust tube Steady condensation means that the flame is lit 200 Agilent 7890 Series Troubleshooting Troubleshooting Tasks 8 To Adjust the FPD Lit Offset To adjust the FPD Lit offset 1 Press Config 2 Scroll to Front detector or Back detector wherever the detector is installed and press Enter 3 Scroll to Lit offset With the Lit offset line highlighted enter the new parameter for the FPD typical value is 2 0 pA and press Enter Agilent 7890 Series Troubleshooting 201 Troubleshooting Tasks When to Change Gas Purifiers 202 Agilent highly recommends using purifying traps in the gas lines to prevent impurities from
141. wagelok caps ECD TCD Detector plug part no 5060 9055 2 Load the inlet maintenance method and wait for the GC to become ready 3 Set the total flow to 40 mL min and purge the inlet for about 1 minute 4 Remove the column if installed 5 Plug the column fitting If the capillary column adapter is installed use a column nut and a no hole ferrule If a 1 8 inch packed column adapter is installed use a 1 8 inch Swagelok cap 5180 4121 If a 1 4 inch packed column adapter is installed use a 1 4 inch Swagelok cap 5180 4120 6 Remove the old septum and replace it with a new one See To change the septum on the purged packed inlet 7 Inspect the O ring and replace it if it is hard and brittle or cracked See To change the O ring on the purged packed inlet 8 If unsure of the quality of the adapter ferrule replace it See To change the glass insert on a PP inlet 9 Configure but do not install a capillary column to put the inlet in pressure control mode 10 Set the inlet temperature to 100 C Agilent 7890 Series Troubleshooting Checking for Leaks 7 11 Enter a pressure setpoint of 25 psi 172 kPa Make sure that the pressure supplied to the GC is at least 10 psi 70 kPa higher than the inlet pressure 12 If pressure cannot be achieved there is either a large leak or the supply pressure is too low 13 Set the Septum purge flow to 3 0 mL min 14 Allow the inlet temperature to stabilize Temperature changes
142. x heaters valves oven heater EPC modules and so forth and becomes ready when all of them reach setpoint If the GC senses a problem in one of these devices the GC will either never become ready or may go into a shutdown state to protect itself or prevent a safety hazard However there may be a time when you do not wish to have the readiness state of a device prevent a run from starting An important example is when an inlet or detector heater is defective Normally this fault prevents the GC from becoming ready and starting a run However you can set the GC to ignore this problem so that you can use the other inlet or detector until the device is repaired Not all devices can be ignored You can ignore the readiness state of inlets detectors the oven or an EPC module The readiness state of other devices and components can never be ignored for example injection devices such as a switching valve or automatic liquid sampler To ignore the status of a device 1 Turn off the device s heater and gas flows as applicable Make sure that it cannot create a safety hazard 2 Press Config then select the element 3 Scroll to Ignore Ready and press On Yes to set it to True You can now use the GC until the device is repaired Do not ignore the readiness state of a device that is being used unless you do not care if it reaches setpoint Be sure to return a broken device to Ignore Ready False after it is repaired Otherwise
143. y that the correct column dimensions are configured accurately including the actual trimmed column length A short lt 15 m 0 58 to 0 75 mm id WCOT column is being used with a split splitless capillary inlet The total flow controller is set for a high flow rate which creates some pressure in the inlet and causes column flow even with a setpoint pressure of zero In these situations an actual pressure may be shown on the display even with a zero setpoint With short 530 to 750 mm columns keep the total flow rate as low as possible for example 20 to 30 mL min Install a longer column with higher resistance for example 15 to 30 m The split vent line or trap may be partly plugged creating an actual inlet pressure higher than the setpoint pressure Check for a restriction in the split vent line See To Run the Inlet Trap Check If using a Mass Selective Detector verify the column outlet for the transfer line is set to MSD Make sure that the auto flow zero is turned on As applicable zero the flow and pressure sensor for the flow module If this does not solve the problem replace the flow module Agilent 7890 Series Troubleshooting FID Does Not Ignite Agilent 7890 Series Troubleshooting GC Not Ready Symptoms 4 Verify that the Lit Offset is lt 2 0 pA Ensure that the FID temperature is high enough for ignition gt 150 C Agilent recommends gt 300 C Check that the FID ignitor glows during ignition se

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