Bulletin 792C Packed Column GC Troubleshooting - Sigma
Contents
1. POE ac eee Problem 795 0323 Column bleed or contamination Contaminated detector or injection port Carrier gas leak Poor carrier gas regulation Gas impurities contaminated gas line Gas flows not within minimum maximum limits including hydrogen and air for FID or poorly regulated flow Defective electrometer detector or cable FID only collector incorrectly aligned ECD only heater wire too close to detector wire causing AC noise Remedy Increase source pressure to 15psig above column head pressure Check correct as necessary see page 3 Replace septum with higher tempera ture type repack column inlet Replace column with known good column If results okay recondition original column Measure flows and verify against manual specifications Allow time for instrument to equilibrate when changing operating temperature or installing another column Troubleshoot per Isolation of Problem Source see page 1 Clean as recommended in instrument manual Replace column with known good column if results okay recondition original column Clean detector and or injection port Check for leaks correct as necessary see page 3 Check gas supply for sufficient pressure Replace tank if near empty Change gas tank clean metal tubing use gas purifier s Measure flows and verify against manual specifications Troubleshoot per solation of Problem Source see page 1 R2. 8 Flow meter To check gas flows 9 Spare recorder and electrometer cables To eliminate the recording system as a source of trouble 10 Instrument manual Isolating the Problem Source To define your problem refer to the Symptoms Index on page 4 Locate your trouble symptom e g broad peaks unresolved peaks long retention times then go to the appropriate point in the Troubleshooting Table pages 5 18 Ifthere is more than one symptom note the possible cause for each If one cause is common to all symptoms this most likely is the source of your problem Note that while the troubleshooting table contains most of the symptoms you will encounter it cannot cover all potential problems When you cannot find a rapid solution by using the troubleshooting table you must systematically isolate the trouble by sequentially eliminating the five potential sources of the problem 1 Rule out operator error by double checking all operating parameters such as temperature carrier gas flow column description etc 2 Checkfora sample problem by injecting a reference standard If you get a good chromatogram the problem most likely is sample related If the chromatogram is not satisfactory the problem probably is column or instrument related 3 Check for a column problem by replacing the column with a duplicate column one known to provide good results under proper conditions If results are good the problem is related to the original co
3. A collection of wire brushes specially tailored to clean FIDs and injection ports that accept 1 4 columns Brass brushes prevent scratching and marring of expensive FID components and save downtime by allowing the detector to be cleaned while hot Each kit includes two detector brushes one injection port tube brush a brass toothbrush for cleaning jets and other odd sur faces and a piece of fine emery cloth to clean electrical contacts Just measure your collector assembly ID and choose the closest kit Instructions are included Description Cat No Bransonic Ultrasonic Cleaner 110VAC 22326 220VAC 22336 Cleaning Solution 1 quart 0 9 liter 22335 Immersion Cleaner 100mL 22662 In Place Detector Cleaner 33000 U Jet and Needle Cleaning Kit 21578 Wire Brush Detector Cleaning Kit Collector Assembly ID 0 145 e g HP 5700 5830 22403 0 187 e g Perkin Elmer Sigma Series 3900 900 22405 0 235 e g Varian 3700 1400 2700 22404 1 CE approved 23 High Capacity Gas Purifier Change purifier tube when pressure drop exceeds 10psi P000356 To reliably protect your GC columns and detectors from oxygen and water vapor damage you should use a gas purifier specifically designed to ensure maximum gas purity The Supelco High Capac ity Gas Purifier tube is heated inside an oven and oxygen and water react with the gettering material in the tube Chemical reaction with the gettering material prevents thes
4. Accuracy 3 of any reading Display mL min or split ratio Optiflow 570 Digital Flowmeter Flow Range 0 5 700mL min Accuracy 2 of any reading Display mL min or split ratio Optiflow 650 Digital Flowmeter Flow Range 5 5000mL min Accuracy 2 of any reading Display mL min or split ratio Description Cat No Model 1010 Liquid Flowmeter 110VAC 56692 U Model 1010 Liquid Flowmeter 220VAC 56693 U Model 1000 Liquid Flowmeter 110VAC 55090 U Optiflow 420 Digital Flow Meter 22806 Replacement Flow Tube 22779 U Optiflow 520 Digital Flow Meter 22910 Replacement Flow Tube 22776 Optiflow 570 Digital Flow Meter 22741 U Replacement Flow Tube 22777 Optiflow 650 Digital Flow Meter 22912 Replacement Flow Tube 22778 SUPELCO Bulletin 792 P000330 Using liquids to detect gas leaks can be poor economy especially in a capillary GC system Even a small amount of liquid leak detector that seeps into a fitting or through the septum can damage your column or create baseline noise GOW MAC gas leak detectors easily and quickly pinpoint gas leaks too small to detect with soap solution GOW MAC gas leak detectors operate on the same principle as a thermal conductivity detector they respond to any gas mixture that has a thermal conductivity value different from that of air With an intrinsically high signal to noise ratio amplification provides maximum usable sensitivity helium leaks of 1 0 x 10 cc sec and refrigerant leaks of 1 0 x 10
5. cc sec are easily detected Both models have a 1 year warranty from GOW MAC Specifications Deluxe Detector Output Audio Frequency changes with concentration adjustable threshold and speaker volume Range High x1 Low x100 Dimensions 10 3 4 x 81 4 x 3 5 8 27 x 21 x 9cm excluding handle Weight 9lb 4 1kg shipping wt 12Ib 5 4kg Power Rechargeable lead acid gel battery 8V selectable 115 230VAC 50 60 Hz Specifications Miniature Detector Output Visual LED bar graph alerts you to leaks Range High x1 Low x100 Dimensions 3 1 4x1 13 16 x 5 1 4 8x 4 5 x 13cm Weight gt 1lb 474g without charger Line Voltage Rechargeable Ni Cd battery 7 2V 800mAmp hr recharger included 115VAC 60Hz or 230VAC 50Hz Description Cat No GOW MAC Gas Leak Detectors Deluxe Model 21 250 22409 Mini Detector Model 21 050 with 115VAC 60Hz recharger 22807 with 230VAC 50Hz recharger 22808 Carrying Case for Mini Detector 22809 1Does not have a CE mark 2CE approved NOTE These GOW MAC gas leak detectors are not intended for determining leaks of combustible gases They are intended for nonspecific applications to determine low level leaks of gases with thermal conductivity different from that of air We recommend a combustible gas detector for monitoring combustible gases in possibly hazardous situations SUPELCO Bulletin 792 Bransonic Ultrasonic Cleaner Ultrasonic cleaning is fast effective and safe and this Br
6. 50 23168 1 We recommend a 9 5mm 3 8 septum to those who previously used the 9mm size Thermogreen LB 1 Septa Inlet temperature 50 C to 300 C Disc Diameter mm Inch Qty Cat No 9 5 3 8 50 20659 U 10 0 13 32 50 20657 U 11 0 7 16 50 20658 12 5 1 2 50 20661 Cylindrical approx 6mm diameter x 9mm Thru Hole Type 100 20667 Half Hole Type 100 20668 Pyrosep S 1 Septa Inlet Temperature 300 C to 400 C Because they are relatively hard Pyrosep S 1 septa must be used with a needle guide to prevent the needle from buckling and only at high temperatures Disc Diameter mm Inch Qty Cat No 6 1 4 10 22369 9 5 3 8 10 22370 U Adapter Rings pk of 2 9 5mm OD x 6mm ID 22338 11mm OD x 9 5mm ID 22607 12 5mm OD x 9 5mm ID 22340 U 1 Use with 6mm septa to replace 9 5mm septa 2 Use with 9 5mm septa to replace 11mm septa 3 Use with 9 5mm septa to replace 12 5mm septa SUPELCO Bulletin 792 Septum Nuts The needle guide in Supelco septum nuts ensures that the needle consistently penetrates the septum in the same place prolonging septum life The guide also prevents the needle from striking the edge of the column or bending during insertion The 9 16 hexagonal nut head accommodates our torque wrench for consistent optimum tightening Each nut is supplied with easily interchanged 1 2 and 1 guides Use 9 5mm septa with each nut The stainless steel nuts hold up under heavy use e g when s
7. 99 0 01 10 0 30 0 0 1 ee Humonics Optiflow Flowmeters e Four flow ranges avail able accurate to within 2 or 3 of any reading e Portable includes stan dard 9 volt battery e Patented U tube design for lighter than air gases e Fault condition display e Automatic power off for extended battery life P000221 e Low battery indicator e Field replaceable tubes e Compatible with electronic pressure control e Computer interface capability on Model 650 These high precision instruments combine the simplicity and versatility of a bubble meter with the speed and accuracy of a microprocessor providing you with a reliable means of measuring gas flow The versatile units can be used with all gases And they feature an easy to read accurate digital display eliminating the need for tedious bubble watching timing and flow rate time conversions The bubble is visible for your observation Optiflow Digital Flowmeters help you comply with the quality protocols of the American Society for Quality Control ISO 9000 and Good Laboratory Practice Each unit is individually calibrated to the registered standards of the National Institute of Standards and Technology and comes with a certificate of calibration A recalibration service is available Optiflow 420 Digital Flowmeter Flow Range 0 5 50mL min Accuracy 3 of any reading Display mL min or linear velocity Optiflow 520 Digital Flowmeter Flow Range 0 5 500mL min
8. Sample solvent interacts with detector 5 Change sample solvent 6 Sample solvent retained by column 6 Change sample solvent e g methanol by active column Problem er SUPELCO Bulletin 792 15 Symptom Possible Cause Remedy Symptom No 28 Retention Time Longer Shorter On Same Column Column temperature too high too low 1 Check temperature with independent thermometer adjust as necessary Carrier gas flow rate too low too high 2 Measure rate with soap bubble flow meter at column exit adjust as necessary Septum or column leak 3 Check correct as necessary Column contamination or deterioration 4 Repack first 6 of column or replace column Recorder problem 5 Check recorder chart speed Sample overload 6 Reduce sample size Normal Problem Problem setae On New Column compared to previous Column too long too short Use tested standardized columns and column of same composition More less packing in column due to packings a Support density greater less than previously used b Column packed more tightly loosely c Column inside diameter greater smaller Too much too little stationary phase on support due to different manufacturing Normal procedures or to errors Stationary phase different or variation in phase composition particularly common with commercial chemicals not manufactured for GC Support type different Problem Problem 795 0352 SUPELCO 16 Bulletin 792 Symptom Possible Cause Sy
9. analysts who want a simple con tinuous reading flowmeter for general GC applications The Veri Flow 500 Electronic Flowmeter is multiple point cali brated to NIST certified volumet ric standards for superior accu racy and to help you comply with ISO 9000 GLP and other P000218 stringent quality control protocols Operation is pulse free unaf fected by temperature or pressure changes and the unit is fully compatible with electronic pressure control systems Operates on internal rechargeable batteries Very low power consumption and automatic shut off Description Cat No Veri Flow 500 Electronic Flowmeter 110VAC 23143 with universal charger 110 240VAC 50 60Hz 23142 1 CE approved 2 Includes 110VAC USA 220VAC European power cords Humonics Model 1000 Liquid Flowmeter e Easy set up and operation e NIST traceable Humonics digital liquid flowmeters replace the tedious and time con suming glass burette and stopwatch traditionally used to measure flow rates a microcomputer and infra red optics are used to track a rising volume of liquid within a tube of precision bore glass Absolute accu wal Y 42 ele racy is established by comparing the W performance of the instrument to an NIST registered burette P000222 Model Flow Range mL min Resolution Calibration Points 1010 0 100 1 999 0 001 0 5 1 5 5 mL m in 2 00 6 00 0 01 1000 0 100 1 999 0 001 1 5 3 5 mL min 2 00 9
10. l 20151 Milano JAPAN Sigma Aldrich Japan K K Chuo ku Tokyo 103 KOREA Sigma Aldrich Korea Seoul MALAYSIA Sigma Aldrich M Sdn Bhd 58200 Kuala Lumpur MEXICO Sigma Aldrich Quimica S A de C V 50200 Toluca NETHERLANDS Sigma Aldrich Chemie BV 3330 AA Zwijndrecht NORWAY Sigma Aldrich Norway Torshov N 0401 Oslo POLAND Sigma Aldrich Sp z 0 0 61 663 Poznah PORTUGAL Sigma Aldrich Quimica S A Sintra 2710 RUSSIA Sigma Aldrich Russia Moscow 103062 SINGAPORE Sigma Aldrich Pte Ltd SOUTH AFRICA Sigma Aldrich pty Ltd Jet Park 1459 SPAIN Sigma Aldrich Quimica S A 28100 Alcobendas Madrid SWEDEN Sigma Aldrich Sweden AB 135 70 Stockholm SWITZERLAND Supelco CH 9471 Buchs UNITED KINGDOM Sigma Aldrich Company Ltd Poole Dorset BH12 4QH UNITED STATES Supelco Supelco Park Bellefonte PA 16823 0048 Phone 800 247 6628 or 814 359 3441 Fax 800 447 3044 or 814 359 3044 email supelco sial com H Supelco is a member of the Sigma Aldrich family Supelco products are sold through Sigma Aldrich Inc Sigma Aldrich warrants that its products conform to the information contained in this and other Sigma Aldrich publications Purchaser must determine the suitability of the product for a particular use Additional terms and conditions may apply Please see the reverse side of the invoice or packing slip AIS
11. pressure will enable you to determine when the gas purifier should be changed NOTE Many chromatographs have an intentional crimp in the carrier gas line between the flow controller and the injection port or employ capillary tubing with a small internal diameter Conse quently the pressure reading at point P3 will be different from the column head pressure reading taken through the septum These restrictions also can make it difficult to obtain sufficient carrier gas flow particularly when converting an instrument for use with capillary columns Testing for Leaks The most common method of leak testing is to apply a liquid e g Snoop or HT Leak Detector and watch for bubbles to appear These liquids can be aspirated into the GC system however and can cause unstable baselines and ghost peaks in subsequent chromatograms To eliminate the risk of contamination use a thermal conductivity leak detector such as a GOW MAC unit These units are extremely sensitive to helium or hydrogen leaks and are equal to liquids in sensitivity for nitrogen and other heavy gases A simple technique for detecting septum leaks while avoiding contamination is to use a Supelco Leak Tester a plastic tube with conical ends When one end is dipped in Snoop capillary action pulls a small amount of the liquid into the tube If a leak is present bubbles appear at this end when the opposite end is pressed against the septum nut Because the liquid doe
12. the information presented in this guide helpful tips to save time and money in chromatography are offered in the following FREE Supelco technical literature Bulletin 741 The ideal ferrule provides a leak tight seal accommodates column OD variations seals with minimum torque and does not stick to the column or fitting This bulletin offers valuable information about choosing the best ferrule for various applications Bulletin 783 Provides instructions for cleaning dirty flame ionization detectors FIDs and offers hints to help prevent contamination Bulletin 898 Provides valuable information about installing and troubleshoot ing gas delivery systems for single GC or multiple GC systems Bulletin 918 The best gas purifier system includes multiple purifiers that help protect each other while protecting columns and detectors This bulletin includes information needed to select suitable purifiers for carrier gas and for air and hydrogen used as fuel gases Publication 395082 Leak resisting low bleed septa improve baseline stability and reduce the occurrence of leak associated problems This publica tion describes tests that show Thermogreen LB 2 septa exhibit low bleed at inlet temperatures up to 350 C Gas Chromatography Troubleshooting Table Abbreviations ECD electron capture detector FID flame ionization detector FPD flame photometric detector NPD nitrogen phosphorous detector TCD thermal conduct
13. 1 16 Description Cat No Drill to fit your column Glasrench l Model A for Supeltex M 1 Supeltex M 2 ferrules 22901 Model C for Supeltex M 2A Supeltex M 4 ferrules 22903 Leak Tester Kit Eliminates placing leak detection fluid a potential contaminant directly onto the septum Dip one end of the leak tester tube into Snoop and place the other end into the septum nut or needle guide Bubbles indicate a leak Kit includes 10 leak tester tubes and 8 ounces of Snoop Leak Tec Leak Detector Use at temperatures up to 210 C Leak Tec leak detector will not bubble ona heated part unless there is a leak 283g pressurized can Description Cat No Leak Tester Kit 22660 U Snoop 8oz bottle 20434 Leak Tec Leak Detector 283g 20566 20 Trademarks Bransonic Branson Cleaning Equipment Co CapSeal Bullet Glasrench OMI PureCol Pyrosep Supelco Supeltex Thermogreen Sigma Aldrich Co Freon VESPEL E I du Pont de Nemours amp Co Inc GOW MAC GOW MAC Instrument Co Hamilton Hamilton Co Hewlett Packard Hewlett Packard Corp Leak Tec American Gas amp Chemical Co Ltd Perkin Elmer Perkin Elmer Corp Shimadzu Shimadzu Corp Snoop Nupro Co Swagelok Crawford Fitting Co SUPELCO Bulletin 792 Deactivated Glass Liners for Packed Column Injection Ports We can prepare liners to your specifications Just call our Ordering and Customer Service Departments for a quote These
14. Bulletin 792C Packed Column GC Troubleshooting Guide How to Locate Problems and Solve Them By applying a systematic approach to troubleshooting you can solve many GC problems on your own The real task is identifying the cause of a problem in the shortest possible time This guide outlines techniques that will enable you to troubleshoot your problem step by step You ll reduce repair costs and instrument downtime Suggestions for Effective Troubleshooting There are five major sources of problems in gas chromatography 1 the operator 2 the sample 3 the column 4 the equipment or electronics and 5 the gas flow system Eliminate these sources in a systemic manner to isolate the cause of a problem A few basic rules make troubleshooting faster and easier Most important are maintaining close observation of operating param eters and a good record keeping system temperatures flow rates chart speeds column type stationary phase type and amount solid support type and mesh size etc Also of primary importance are reference chromatograms and reference standards containing known concentrations of the components in your samples with no extraneous components Many hours can be wasted hunting problems within an instrument or column when the problem is in fact the sample being analyzed If your chromatographic system separates the reference standard well and reproducibly any problem most likely is related to the sample Yo
15. L minute and you can use it with any common carrier gas except Dimensions of OMI Purifiers hyd OMI 2 yarogen Tube 6 15 2cm x 5 8 1 6cm OD The stainless steel converter tube is 10 x 1 2 OD The split sided Tube Holder 10 25 4cm x 1 1 2 3 8cm OD p i l Endfittings 2 1 2 6 4cm heater is 10 long An integral mounting bracketallowsyoutobolt oMIi 4 the unit to a bench top or wall The 90 watt power consumption Tube 12 30 5cm x 1 2 5cm OD makes the unit as economical to operate as a light bulb Tube Holder 16 40 6cm x 1 1 2 3 8cm OD Endfittings 2 1 2 6 4 1 year guarantee elements guaranteed for 90 days E pein Description Cat No Description Cat No High Capacity Gas Purifier OMI 2 Purifier Tube 23906 110VAC 1 8 Fittings 23800 U OMI 2 Tube Holder 1 8 fittings 23921 110VAC 1 4 Fittings 23802 Seal Kit for OMI 2 Tube Holder 220VAC 1 8 Fittings 23801 includes 2 Teflon seals and tool 23917 220VAC 1 4 Fittings 23803 OMI 4 Purifier Tube 23909 Replacement Purifier Tubes OMI 4 Tube Holder 1 8 fittings 23926 1 8 Fittings 22396 OMI 1 Replacement Tube 1 4 Fittings 22398 includes 2 ferrules 23900 U 3 8 Ferrules pk of 10 22311 CE approved 1 4 to 1 8 Swagelok SS Reducer 21517 Pressure Gauge Kit Use to indicate when the high capacity gaspurifier tube should be replaced 2 5cm gauge 0 100psi NPT to Swagelok adapter 18 1 2m of 1 8 copper line 1 8 tee installation instru
16. No 18 Squared Flat Topped Peaks 1 Electrometer saturated normal for solvent 2 Recorder defective Normal Problem 795 0342 Symptom No 19 Round Topped Peaks 1 FID detector overload 2 Recorder gain too low Normal Problem 795 0343 12 1 2 1 2 Remedy Reduce sample size Use solvent flush technique so sample is contained in barrel not in needle see pages 3 and 4 Use less volatile solvent Reduce sample size Troubleshoot per instruction manual Decrease sample size Adjust control SUPELCO Bulletin 792 Symptom Possible Cause Remedy Symptom No 20 Cigar Top Peaks f Normal Problem 795 0344 ECD detector overload Reduce sample size Symptom No 21 Clipped Peaks Column Efficiency Exceptionally High Recorder or instrument zero below minimum Shunt recorder leads and set recorder moveable range of recorder pen baseline adjustment zero to approximately 5 of full scale Normal Problem 795 0345 Symptom No 22 Baseline Rise Before or After Peak Sample decomposition Use inert column and packing Normal A Problem Problem 795 0346 SUPELCO Bulletin 792 13 Symptom Possible Cause Remedy Symptom No 23 Baseline Change After Large Peak Contamination water or large 1 Repack first 6 of column or replace component stripping contaminants from pre column column Column not conditioned properly 2 Reconditio
17. adsorbing on injection port transfer lines column or glass wool Two compounds co eluting Needle hitting packing in column inlet breaks particles and creates active sites Column overload Two components co eluting Sample condensation Sample decomposition Remedy Increase temperature do not exceed maximum temperature for column If retention times have not changed from when column was new replacing first 6 of packing or replacing pre column may help If retention times have changed replace column Use more inert system all glass Teflon specially designed packing on column injection proper glass wool type etc Increase sensitivity reduce sample size reduce temperature approxi mately 20 C look for partial separa tion Remove several cm of packing from inlet Decrease sample size or select another column with higher stationary phase loading Alternatively select a different stationary phase with greater solubility for the component exhibiting this behavior Increase sensitivity reduce sample size reduce temperature approxi mately 20 C look for partial separation Check injection port and column temperatures increase if necessary Use inert system and deactivated packing 11 Symptom Possible Cause Symptom No 17 Split Peaks 1 Gross detector overload 2 Sample flashing prior to injection simulates two injections Normal Problem 795 0341 Symptom
18. ae Normal Problem 795 0318 O SUPELCO Bulletin 792 Possible Cause Symptom No 5 Quantification Not Reproducible Wrong sample ai Incomplete sample injection a2 Injection port or column tempera ture too low Incorrect slope sensitivity with electronic integrator Differing detector response for different components Adsorption of components by packing glass wool tubing or transfer lines Internal standard not compensat ing for all components in sample Slope sensitivity of integration not high enough for late eluters Insufficient resolution of peaks or peak tailing Sample too small for accurate counting by integrator Adsorption of components and saturation of active sites with sample priming the column Column not conditioned properly or contaminated or temperature too high Recorder problem Septum leak Wrong gas e g argon methane with FID Contamination Too much too little gas flow TCD imbalance in column flow Contaminated detector e g NPD contaminated with Snoop ECD contaminated with chlorinated solvents Electrometer or detector problem Remedy Verify using known standard al Use solvent flush technique see pages 3 and 4 a2 Increase temperature a3 Adjust slope sensitivity b1 Determine correction factors and or use internal standards technique b2 Use deactivated system c1 Use multiple internal stand
19. ansonic cleaner has more ultrasonic power than most comparable models Ensures faster more thorough cleaning of dirt protein residue etc from your glassware fittings syringes and needles and other apparatus Recessed cleaning tank is enclosed in durable solvent and impact resistant plastic for longer life Tank Size 5 1 2 x 6 x 4 deep 14 x 15 x 10cm 1 2 gallon 1 8 liter capacity Overall Size 7 1 2 x 81 2 x 9 19 x 22 x 23cm Weight 7 Ibs 3 2kg Immersion Cleaner An aqueous and nontoxic surfactant solution that removes heavy deposits of silica from a detector Recommended for dirty detec tors not effectively cleaned by our in place detector cleaner Cat No 33000 U Mix concentrate 1 10 with water In Place Detector Cleaner A halocarbon liquid that cleans the detector in place Just inject microliter quantities into a packed column while it is connected to a lighted flame detector HF produced by combustion of the cleaner removes silica deposits from detector electrodes Also useful for removing greases and oils from glassware syringes etc 100mL bottle Jet and Needle Cleaning Kit Ten wires in each of five sizes 0 00350 0 00497 0 00659 0 00815 and 0 01207 OD plus a bottle of syringe cleaning solution Perfect for cleaning small orifices such as FID jets and syringe needles Packaged in a reusable box that prevents wires from being dam aged during storage Wire Brush Detector Cleaning Kit
20. ards c2 Use multiple internal standards d Modify operating parameters or replace column to improve resolution and eliminate tailing e Increase sample size or electrom eter range setting f Use deactivated system Reduce column temperature to ambient If baseline normal check system with good column If okay recondition original column Set attenuation to infinity If recorder does not go to electrical zero troubleshoot recorder per manual Check for leaks correct if necessary see page 3 Verify gases are correct for instrument and detector as specified in manual Turn off injection port heat If zeroing capability returns clean injection port liners etc Check flow adjust to within manual specifications Check flow adjust as necessary Avoid sources of contamination Troubleshoot per instrument manual Symptom Symptom No 7 Baseline Drift Normal Problem 795 0319 Possible Cause Carrier gas flow changing with temperature during emperature programming Septum or column leak Septum bleed or septum fragments in column Column bleed or contamination Gas flows not within minimum maximum limits including hydrogen and air for FID or poorly related flow Insufficient instrument warm up time or temperature equilibration time Defective electrometer or detector Contaminated detector or injection port Symptom No 8 Irregular or Unstable Baseline baseline nosie Normal
21. brate until smooth If this does not solve problem repack column Symptom No 31 Packing Compacts or Shirks After Conditioning 1 Slight compacting may occur when 1 Normally not a problem use column packings are exposed to pressure 2 Significant compacting bed contracts 2 Column may not be properly packed 3 or more Add more packing Symptom No 32 Low Carrier Gas Flow Large Pressure Drop Overtightened septum 1 Loosen septum Insufficient Carrier gas source 2 Increase pressure by 10psig pressure Insufficient Source pressure for 3 Flow control must have 10 15psig temperature program higher than maximum pressure reached at maximum temperature to function properly Plugged injection port carrier gas line 4 Replace tubing or gas purifier s as or gas purifier s necessary Column over packed or glass wool too 5 Increase carrier gas pressure If flow tight still insufficient install another column Note not all packings have same pressure drop If flow okay original column was problem If flow low check plumbing system for flow restrictions plugged detector plugged gas filter etc Symptom No 33 Column Deteriorates Too Soon After Installation peaks tail are poorly resolved etc 1 Column operated near or above 1 Use higher temperature phase maximum temperature limit of packing Use shorter column and lower temperature if possible Reduce temperature when column not in use R
22. ctions 1 First time users must order both purifier tube and corresponding holder Holder is reusable 2 Will not fit OMI 2 tube holder use with OMI 1 installation kit only kit no longer available Cat No 20392 Description Pressure Gauge Kit For more information or current prices contact your nearest Supelco subsidiary listed below To obtain further contact information visit our website www sigma aldrich com see the Supelco catalog or contact Supelco Bellefonte PA 16823 0048 USA ARGENTINA Sigma Aldrich de Argentina S A Buenos Aires 1119 AUSTRALIA Sigma Aldrich Pty Ltd Castle Hill NSW 2154 AUSTRIA Sigma Aldrich Handels GmbH A 1110 Wien BELGIUM Sigma Aldrich N V S A B 2880 Bornem BRAZIL Sigma Aldrich Quimica Brasil Ltda 01239 010 Sao Paulo SP CANADA Sigma Aldrich Canada Ltd 2149 Winston Park Dr Oakville ON L6H 6J8 CZECH REPUBLIC Sigma Aldrich s r o 186 00 Praha 8 DENMARK Sigma Aldrich Denmark A S DK 2665 Vallensbaek Strand FINLAND Sigma Aldrich Finland YA Kemia Oy FIN 00700 Helsinki FRANCE Sigma Aldrich Chimie 38297 Saint Quentin Fallavier Cedex GERMANY Sigma Aldrich Chemie GmbH D 82041 Deisenhofen GREECE Sigma Aldrich o m Ltd llioupoli 16346 Athens HUNGARY Sigma Aldrich Kft H 1067 Budapest INDIA Sigma Aldrich Co Bangalore 560048 IRELAND Sigma Aldrich Ireland Ltd Dublin 24 ISRAEL Sigma Israel Chemicals Ltd Rehovot 76100 ITALY Sigma Aldrich s r
23. deactivated glass liners prevent reaction between active sample components and the injection port s metal surfaces Instrument Liner Mfr __Manufacturer amp Model Descipton PartNo Cty Cat Now Hewlett Packard 5700 5830 40A 5880A 5890A e Glass linor 5080 8732 5 20508 91 5mm x 3mm OD 1 8mm ID 25 20511 Perkin Elmer 3920 Glass liner 0009 1958 1 26302 2 5mm ID Glass liner small bore 0009 1614 1 26301 143mm x 4 6mm OD 1 5mm ID Perkin Elmer 8000 Sigma 2000 2100 Sigma 1B 4B amp 300 manufactured 1978 or later Glass liner 0330 2221 1 26300 U 2 5mm ID 5 26409 Glass liner small bore 0330 2243 25 26464 101mm x 4 6mm OD 1 5mm ID 1 26305 Perkin Elmer Auto System Model 9000 Unpacked ee m ee mete Seca 3mm ID 5 26316 05 112mm x 6mm OD 25 26316 25 Packed deactivated glass wool m gt m ees ear 3mm ID 5 26317 05 112mm x 6mm OD 25 26317 25 Shimadzu Wool packed 104mm x 4 5mm OD 3mm ID 221 14755 1 26332 Varian Universal Flash Injectors 1060 60 3300 3400 3500 3600 older 3700 VISTA Glass injector insert 37 000813 00 1 26369 r wool packed 5 26426 72mm x 6 3mm OD 25 26481 Varian Moduline and Other Older Models Glass insert 6 000107 01 10 26370 U 5 2 14cm x 1 8 ID 1 8mm ID G000405 412 PureCol Column Inlet Liners When nonvolatiles accumulate in the column inlet you must replace several inches of packing or the entire column Asilanized glass PureCol liner i
24. e contaminants from returning to the gas stream The High Capacity Gas Purifier also removes carbon monoxide and carbon dioxide A single replaceable High Capacity Gas Purifier tube can remove 14 liters of oxygen or 35 liters of water vapor STP It removes OMI Indicating Purifiers e Simultaneously remove O water va por CO CO most sulfur com pounds most halogen compounds alcohols phenols to less than 10ppb e Purify helium hydrogen nitrogen argon methane e Color change indicates purifier ex haustion e Glass body does not diffuse air or off gas e dealfor Hall ECD GC MS detection systems P000245 e OMI 4 purifier protects multiple instruments three times the capacity of OMI 2 tubes Install an OMI purifier downstream from your primary gas purify ing device and tell at a glance whether or not oxygen and water vapor are being effectively eliminated from your system The OMI purifier will provide point of use gas polishing and final visual assurance of gas quality before the gas enters the GC OMI purifier tubes contain Nanochem resin developed for the demanding gas purity needs of the semiconductor manufacturing industry As little as 1 ppm of oxygen or water will change the indicating resin from black to brown oxygen and water from at least 60 tanks of heavily contaminated gas gas containing 100ppm of oxygen and or water It effi ciently removes oxygen and water at gas flow rates up to 1100m
25. ealign as required Reposition heater wire SUPELCO Bulletin 792 Symptom Possible Cause Symptom No 9 Cycling Baseline Drift Poor instrument location drafts changes in ambient temperature etc Defective detector temperature Normal controller Defective oven temperature controller Carrier gas flow irregular insufficient supply pressure Defective carrier gas regulator ee te TTNA Defective carrier gas flow controller Problem 795 0324 lf using pumped gases such as from hydrogen generator sensitivity too high Symptom No 10 Spikes regular Condensate or dust particles in FID LO Contaminated gases Normal g Defective electronics or detector e d I I Problem Problem 795 0320 Symptom No 11 Spikes irregular or erratic Defective cable intermittent shorting ECD heater wire and detector wire too close or loose FID insufficient hydrogen flow L Electronic interference from external Normal source otitis Problem 795 0321 Symptom No 12 Negative Peaks Recorder improperly connected polarity reversed or sample injected into wrong column TCD only impurity in carrier gas Normal Problem 795 0322 SUPELCO Bulletin 792 Remedy Close windows relocate instrument etc Replace temperature sensing probe Replace temperature sensing probe Change gas tank Replace regulator Replace flow controller Reduce detector sensitiv
26. echnique This technique Figure C re duces the problem of irreproducible injection volumes when making syringe injections by hand a Eliminate sample hang up in the needle by first clean ing the syringe then drawing in a small aliquot of solvent b Remove the syringe from the solvent and draw in a small amount of air c Draw in the desired amount of sample Moisture Trap Oxygen Trap Particle Trap Carrier Gas Source Typical Location NOTE Our High Capacity Gas Purifier combines the functions of a moisture trap and an oxygen trap see products pages OMI Indicating Purifier Detector Column G001131 SUPELCO Bulletin 792 3 d Remove the syringe from the sample and draw in alittle more air e Verify the amount of sample in the syringe barrel This is only possible with syringes that do not have plungers in the needle f Quickly and smoothly inject sample into the chromatograph 4 Syringes with Needle Plungers Improve sample reproducibil ity by using a syringe with a plunger in the needle This eliminates sample retention in the needle dead volume The solvent flush technique above may be useful since a small amount of sample hang up can still occur Figure C Solvent Flush Technique Air Plunger a Y Solvent Air Air manger lt M 1 7 1111 111111 gt Sample Solvent G001132 1 133 Other Useful Publications In addition to
27. emove column from oven when Normal another column is used at higher temperature Water or oxygen in carrier gas 2 Use carrier gas purifier s and contaminating column appropriate grades of gases Replace tanks before pressure becomes too low 300psig Column leaks causing contamination 3 Check for leaks prior to use Always by oxygen allow column to cool before removing from GC to prevent exposing a hot column to air Column damaged by aqueous 4 Use precolumns or repack column inlet samples serum plasma other to extend column life Problem 795 0356 complex samples These samples can 1 strip phase from support 2 chemically react with phase 3 build up on column and possibly destroy it injection end first SUPELCO 1 S Bulletin 792 Thermogreen LB 2 Septa e Extremely low bleed from 100 C to 350 C e Already conditioned ready to use e Easier needle penetration high puncture tolerance Disc Diameter mm Inch Qty Cat No 5 0 3 16 50 20638 6 0 1 4 50 20651 9 5 3 8 50 20652 9 5 3 8 250 20666 9 5 3 8 1000 20677 10 0 13 32 1000 23157 11 0 7 16 50 20654 11 0 7 16 250 23163 11 0 7 16 1000 23164 11 5 11 24 50 23154 12 5 1 2 50 20660 U 12 5 1 2 250 20678 14 0 9 16 50 20662 U 16 0 5 8 50 20663 17 0 21 32 50 23159 Cylindrical for Shimadzu instruments Plug Type 10 20608 Plug Type 50 20633 Drilled for Solid Phase Microextraction 9 5 3 8 25 23161 9 5 3 8 50 23162 U 11 0 7 16 25 23167 11 0 7 16
28. emoved with the carrier gas flowing can blow packing from the column NOTE When storing columns cap the ends with metal Swagelok caps to prevent diffusion of air into the column and subsequent oxidation Plastic caps do not prevent diffusion of air into a column Sample Injection Improper sample injection can cause many problems in gas chromatography To ensure that your injections are accurate and reproducible we recommend the following general guidelines and procedures A Syringe Size Always use a syringe large enough that the desired sample volume does not fill it to capacity and small enough that the sample volume is not less than approxi mately 10 of its capacity B Injection Technique Sample injection should be smooth and rapid with quick removal of the syringe after injection in order to avoid peak broadening C Sample Size Reproducibility Many problems in chromatogra phy result from difficulties in reproducing the size of a sample Some techniques which will help ensure reproducible samples are 1 Automatic Injectors These devices improve sample re producibility by virtue of consistent mechanical operation Each step sampling sample injection syringe cleaning is repeated precisely 2 Sampling Valve Injection Sample size is determined solely by sample loop size and injection is rapid and precise Reproducibility is improved because chances for variability are greatly reduced 3 Solvent Flush T
29. epta are replaced daily We also recommend using them for reactive samples such as chlorinated pesticides Aluminum nuts offer economy in light use or when samples are nonreactive i e when metal columns are used Nut N 1 fits PE 3920 900 Sigma series HP 5700 other ports accepting 1 4 Swagelok nut 7 16 threads 20 inch Nut N 2 fits Varian 3700 other ports accepting 1 4 nut 7 16 threads 24 inch Use with packed columns only P00261 Description Cat No Septum Nut N 1 Stainless Steel 22399 All Aluminum 22497 Septum Nut N 2 All Aluminum 22402 1 Aluminum needle guide Torque Wrench 9130363 The handle of the Supelco septum nut torque wrench slips when preset torque 8 inch lbs is reached Helps prevent leaking septa excess bleed and difficult septum penetration Deepwell socket 9 16 fits over the Supelco septum nut even with a needle guide attached Description Cat No Torque Wrench 22661 19 Select the best ferrule for your application Supeltex ferrules form leaktight seals without sticking to your column And they don t require back ferrules We highly recommend Supeltex M 4 and Supeltex M 2A ferrules for glass columns Supeltex M 2A and Supeltex M 2 ferrules for metal columns P000182 Ferrule Max Temp Characteristics Supeltex M 1 250 C Ideal for connections to mass spectrometers High reusability ceramic filled Teflon Isothermal use only Supel
30. f necessary b Decrease injection port temperature c Decrease column temperature Measure flow rate adjust if necessary see page 2 Inject standard on known good column If okay original column is bad Use properly treated glass wool i e H PO for free acid analysis silicone treated for other compounds If sample has never been analyzed and is chemically active you may need a special column Change column or solvent Symptom Normal Problem 795 0316 Possible Cause Symptom No 3 Low Detector Response all peaks retention times correct Poor injection technique Sensitivity setting wrong or sample too small Defective syringe Septum leak Injection port temperature too low for sample FID only low hydrogen flow or air flow incorrect FID only low oxygen level in com pressed air FID only faulty connection between FID collector and voltage source Dirty ECD For TCD a Carrier gas flow rate incorrect b Cell voltage incorrect Sample adsorbed by column glass wool tubing etc FPD only hydrocarbon eluting with sample causing diminished response due to quenching effect Symptom No 4 Low Detector Response all peaks retention times too long Normal Problem Low carrier gas flow rate Carrier gas leak at septum or column connections Column temperature too low Column worn out or conditioned at too high a temperature 11 12 Remed
31. ity or decrease output pressure from generator Clean detector check column ends to ensure glass wool is in place Replace gases or insert liquid nitrogen trap in gas line Check recorder cables and detector electrometer cables Troubleshoot electronics and detector per solation of Problem Source see page 1 Replace cable Check wire position relocate if necessary Increase flow Relocate instrument determine possible interference sources nearby transmitter site etc Reverse recorder connections or polarity switch Install or replace carrier gas purifier s Symptom Possible Cause Remedy Symptom No 13 Extra Peaks peaks similar to previous sample appear when solvent alone is injected l Previous Sample Normal solvent injected after sample Problem solvent injected after sample 795 0336 Symptom No 14 Extra Peaks unlike peaks in previous sample 1 Normal rE Problem Problem 10 Dirty syringe Column adsorbing then desorbing sample particularly in temperature program Adsorption in transfer line Septum bleed particularly in tempera ture program Peaks from previous runs particularly if very broad with short retention time Impurities from sample solvent sample container e g plasticizer from cap liners or contaminated glassware labware or reagents used in sample preparation particularly when excess reagents are concentrated in wo
32. ivity detector Symptoms Index Symptom Symptom No Baseline changing 23 cycling 9 dip 25 26 drift 7 drop 24 noise 8 off scale zeroing problem 6 rise 22 spikes irregular spikes regular 10 Carrier Gas low flow rate 32 Column Life short 33 Column Packing compacted 31 gaps in 30 Detector Response low 3 4 Peak Shapes Incorrect cigar top 20 clipped 21 round top 19 skewed leading edge 16 split 17 square top 18 tailing 15 Peaks broad solvent 27 missing all 1 missing some 2 negative 12 random extra peaks 14 sample memory peaks 13 unresolved 29 Quantification irreproducible 5 Retention Time prolonged or shortened 28 SUPELCO Bulletin 792 Troubleshooting Table Symptom Possible Cause Symptom No 1 No Peaks Detector or electrometer power off 1 fuse blown Sample injected in wrong column 2 multiple column chromatograph FID not lit 3 No carrier gas flow 4 Normal Defective syringe 5 Column or septum leak 6 Injection port temperature too low 7 sample not vaporized Problem 795 0314 Defective recorder 8 Defective detector electrometer or 9 cable Bad connection between FID collector 10 and voltage source Symptom No 2 Missing Peaks Solvent Peak Only 1 Sample too dilute 1 Column or septum leak 2 Incorrect temperatures 3 a Injection port or column tempera ture too low sample not vaporized Norma
33. l b Injection port temperature too high for thermally labile compounds c Column temperature too high sample eluting in solvent peak Flow rate incorrect 4 Sample adsorption by column or glass 5 Problem wool 795 0315 Column cannot separate components 6 from solvent Problem 795 0317 SUPELCO Bulletin 792 Remedy Check detector electrometer settings and fuses Reinject sample in proper column Use mirror over exhaust to check FID If lit water condenses on mirror If not lit light flame Check hydrogen and air flows Measure flow at detector or column exit If no flow check for leaks or obstruc tions at column connection and septum Replace syringe Replace septum Check column connections Increase injection port temperature but not in excess of liquid phase tempera ture limit or inject sample directly onto column packing Check recorder connections Check recorder zero Troubleshoot recorder according to instruction manual Check collector voltage and connec tions per instrument manual Check collector spring clip connection Check system by injecting standard If okay increase sensitivity or inject larger or more concentrated sample Check for leaks See page 3 Tighten connections Replace septum a Ensure column temperature setting is correct for column being used and sample being analyzed then verify that oven is operating at selected temperature Increase temperature i
34. lumn If the symptom persists the problem is related to the instrument 4 Isolate equipment related problems by listing the equipment systems which can cause the observed symptoms e g broad peaks with long retention times can be caused by problems in 1 carrier gas system 2 column heating ISO 9001 REGISTERED 1999 Sigma Aldrich Co system or 3 injection port heating system Next isolate the problem by examining each suspected system Isolate possible electronic system malfunctions detector electrometer recorder wiring by performing the following checks If your instrument is equipped with dual channels detector electrometer recorder etc see paragraph c a Check the recorder by setting the gas chromatograph attenu ation to infinity The recorder pen should go to electronic zero If the symptom baseline drift noise etc disappears the recorder is not the problem If the symptom continues refer to the recorder instruction manual b To isolate the detector FID as the source of trouble turn off the instrument and disconnect the cable at the detector end from the detector to the electrometer If the symptom disappears when power is on the problem is in the detector If the symptom continues disconnect the same cable at the electrometer If the symptom now disappears the cable is defective If the symptom still continues refer to the elec trometer instrument manual Note To prevent ind
35. mptom No 29 Unresolved Peaks On Column Which Previously Produced Wrong column temperature Good Results Wrong carrier gas flow rate Sample problem a Sample too large b Sample concentration different from previous analysis minor peak swamped by major peak Poor injection technique slow Column contaminated or deteriorated Normal 795 0356 Problem Problem 795 0354 After Previous Column of Same Column too long too short Composition Produced Good Results More less packing in column due to a Support density greater less than previously used b Column packed more tightly loosely c Column inside diameter greater smaller Too much too little stationary phase on support due to different manufacturing procedures or to errors Normal n stationary phase different or variation in phase composition particularly common with commercial chemicals not manufactured for GC Support type different Problem Problem 795 0355 SUPELCO Bulletin 792 Remedy 1 Check and adjust temperature 2 Check and adjust flow rate a Reduce sample size b Reduce sample size 4 Make smooth rapid injections 5 Repack first 6 of column or rep column Use tested standardized columns and packings lace 17 Symptom Possible Cause Remedy Symptom No 30 Large Gaps Appear In Packing visible in a glass column Column improperly packed Add enough packing to fill voids then gently vi
36. n column liquid phase being stripped Pressure imbalance when gas 3 Correct pressure imbalance sampling valve activated Normal Problem Problem 795 0347 Symptom No 24 Baseline Drop After Peak FID only flame extinguished Sample too large 1 Decrease sample size Incorrect gas flows 2 Check and adjust carrier gas hydrogen and air Flame tip plugged 3 Clean or replace flame tip Collector and flame tip not located 4 Adjust collector position properly whistling or humming noise often heard Normal Problem 795 0348 SUPELCO 1 an Bulletin 792 Symptom Possible Cause Remedy Symptom No 25 Negative Dips After Peaks Only after large peak such as solvent 1 Decrease sample size sample too large After all peaks with ECD dirty detector 2 Clean detector cell Normal Problem 795 0349 Symptom No 26 Negative Dip Before Peak Pressure imbalance when gas sampling Correct pressure imbalance valve activated Normal Problem G0001158 Symptom No 27 Broad Solvent Peaks 1 Dead volume in injection port due to 1 Use on column injection Ensure poor column installation proper column connections particu larly when changing from one column diameter to another 2 Normal with very dilute sample as in 2 trace analysis 3 Poor injection technique 3 Make smooth rapid injections see Normal page 3 4 Injection port temperature too low 4 Increase injection port temperature 5
37. nserted in the column inlet solves this problem simply and inexpensively When column performance begins to deteriorate you can quickly and conveniently replace the insert often without removing the column from the instrument Replacement time is comparable to replacing a septum Replace the PureCol liner when you change the septum or when you analyze a new type of sample PureCol liners are available in two sizes The smaller size fits 2mm ID glass columns with chamfered ends and 7cm of straight unpacked inlet The larger size fits any 4mm ID glass column that has 7cm of straight unpacked inlet Use PureCol liners with a 2 Scm 21 gauge or finer needle Description Qty Cat No For 2mm ID Columns chamfered inlet only 10 20534 50 20536 For 4mm ID Columns 10 20540 U 50 20543 Order your glass column with a PureCol liner already in place at 713 0449 no extra cost Just specify glass column with PureCol liner on your order SUPELCO Bulletin 792 1 Humonics Veri Flow 500 Electronic Flowmeter e Calibrated for nitrogen helium hydrogen air 5 argon methane certificate supplied e Range of 5 500mL min accurate to within 2 of reading or 0 25mL whichever value is larger e Continuous readings in volume linear velocity or split ratio e EPC compatible e 9 pin RS 232 communication port for recording data e Power adapter jack and recharger e Only4x5x 3 10x 12 5 x 7 5cm An outstanding instrument for
38. olumn This generally is caused by 1 insufficient source pressure 2 leaks and or 3 an unusually large pressure drop across one of the components in the system Verify the column carrier gas flow at the detector exit using a flow meter Wedo not recommend using arotameter for measuring gas flow because a specific rotameter is required for each type of gas used and rotameters exhibit a linear response with pressure changes When using a bubble flow meter use the following equation to verify that the carrier gas flow rate is properly adjusted TimeGeo Volume Observed cc x 60 sec min Desired Flow cc min Where Time Sec time required for bubble to travel observed distance Volume Observed volume indicated by soap bubble flow meter Desired Flow rate specified by method being used Example Obtain a flow rate of 20cc min using a 10cc soap bubble meter Time sec 10cc x 60 sec min 20cc min Time 30sec If the time required is not equal to the calculated time adjust the carrier gas flow rate If sufficient flow cannot be obtained by adjusting the flow control valve the problem probably is due to inadequate source pressure measured at P1 in Figure B Increas ing this pressure usually will provide adequate flow Normally a source pressure of 60psig is sufficient for 6 12 foot columns Increasing the column length oven temperature and or flow rate will require raising the source pressure The source
39. pressure is particularly important if you are using a temperature program since the pressure must be 10 15psig in excess of the column pressure drop at the maximum temperature This pressure differ ence allows the differential flow controller to function properly If the correct pressure difference is not maintained carrier gas flow will drop drastically at elevated temperatures Other common causes of inadequate gas flow are leaks in the system anda large pressure drop across one or more of the system components The use of pressure gauges can save considerable time when isolating these problems Common leak points are column connections the septum and connections for the various valves and gas purifiers A pressure gauge installed between the flow control valve injection port P3 in Figure B indicates column head pressure Alow reading at this point indicates a leak between P3 and the detector outlet e g a defective column septum etc or a large pressure drop across an upstream component e g a plugged gas purifier Alternatively an OMI Indicating Purifier will tell you at a glance whether leaks are present see products pages A high pressure reading at P3 indicates an over tightened septum dirty detector too tightly packed column etc Low pressure readings on a pressure gauge at P2 will reveal an exhausted High Capacity Gas SUPELCO Bulletin 792 Purifier larger than normal pressure drop Routine observation of this
40. rk up Condensed carrier gas impurities eluting during temperature program ming Trace impurities in lab atmosphere Air peaks or water peaks Multiple or incomplete derivatives formed in sample work up Sample decomposition Try new syringe and clean solvent If extra peaks disappear clean syringes more thoroughly Use more inert column materials tubing packing glass wool Use glass lined stainless steel for transfer lines Turn off injector heater If extra peaks disappear operate at lower injector temperature or use high temperature septa Let analysis run longer then repeat Run solvent blank with clean syringe If extra peaks appear change solvent if no extra peaks appear run solvent blank through entire sample work up If no extra peaks appear impurities are from sample If extra peaks appear repeat analysis of solvent blank for each step of work up to isolate source Install or replace carrier gas purifier s Analyze lab environment take corrective action as necessary Normal with TCD using syringe injection or aqueous samples Re evaluate derivatization procedure Reduce temperature and or use different column SUPELCO Bulletin 792 Symptom Symptom No 15 Tailing Peaks Normal Problem Symptom No 16 Leading Peaks Normal Problem SUPELCO Bulletin 792 Possible Cause Column or injection port temperature too low Column deteriorating Active sample
41. s not contact the instrument there is no risk of contamination Problems Related to Column and Septum Removal and Installation Improperly installed columns and septa are a frequent source of leaks and are the most common cause of glass column breakage An incorrectly tightened septum nut presents problems such as excessive septum bleed premature septum leaks and low carrier gas flow rates We offer two torque wrenches to help ensure correct installation of columns and septa The Glasrench used for installing columns is available in two torque settings to provide the correct torque for the various types of ferrules The Supelco septum nut torque wrench ensures that the correct torque is consistently applied when installing septum nuts These tools save time and money by eliminating over tightening minimizing leaks and col umn breakage When changing columns or septa itis important that you first turn off the chromatograph oven and allow the column to cool for 10 15 minutes then turn off the carrier gas This procedure protects Figure B Typical Carrier Gas System your column in two ways allowing the column to cool before turning off the carrier gas prevents oxidation of the column packing which can occur when a hot column is exposed to oxygen in the air Allowing the column pressure to drop to ambient pressure prevents the packing from blowing out of the column ends A sudden change in pressure when a column or a septum is r
42. tex M 2 350 C High reusability du Pont VESPEL SP 1 100 polyimide Supeltex M 2A 400 C Seals at 1 4 turn past fingertight High reusability du Pont VESPEL SP 21 Won t stick to metal or glass 85 polyimide 15 graphite Supeltex M 2B 350 C Conforms easily to capillary column ensuring an effective seal and du Pont VESPEL SP 211 less chance of breakage 10 Teflon graphite 75 polyimide Supeltex M 4 450 C Seals at 1 4 turn past fingertight Maximum sealing surface contact flexible graphitere reduced risk of column contamination at installation O Ring 200 C Seals column having OD over or under specifications silicone Supeltex Ferrules for Packed Columns Glasrench Wrench Supeltex Column OD Ferrule Type 1 4 6mm 1 8 1 16 Temp Limit Cat No Cat No Cat No Cat No Qty M 1 22086 U 22089 22496 22386 10 250 C 22087 U 22309 100 M 2 22320 U 22321 20644 U 10 350 C 22475 _ 22476 50 9130289 Lire m pe 22393 os 22487 U b Our Glasrench lets you consistently apply just the correct force eo 7 7 needed to tighten the ferrule the wrench slips when too much Ingemed Blank 7 j J 22488 10 forceis applied You know when to stop tightening and you don t i 7 Se 22493 22491 22495 T damage your column Because different ferrules require different en E 7 J amounts of tightening force we offer two color coded models O Rings z x fi 1 200 C 20407 B 20406 400 9 16 for 1 4 fittings Ferrule ID 1 4 6mm 1 8
43. ucing extraneous noise onto the cable it may be necessary to install a coaxial cap on the free end c If your chromatograph is equipped with dual detector chan nels you have a simple but effective alternate means of identifying the problem source If the symptom occurs in channel A disconnect at the detectors the cables which connect channels A and B detector outputs to channels A and B electrometer inputs Figure A Reconnect the cable from electrometer B input to detector A output This applies the signal from the channel A detector output to the channel B electrometer input and recorder If the symptom does not appear on recorder channel B after this cable change either the channel A electrometer recorder or cable s is defective Ifthe symptom is not eliminated the channel A detector is the problem source 5 To check the carrier gas system for possible problems refer to the following section Checking the Carrier Gas System Figure A Checking for an Electronics Problem in a Chromatograph Equipped with Dual Detector Channels Detector A Alternate Connection When Problem is in ChannelA Recorder A 7 Alternate Connection When Problem is in ChannelB a PS Detector B Recorder B 712 0082 Checking the Carrier Gas System A typical carrier gas system is illustrated in Figure B The most common problem in this system is insufficient carrier gas flow through the chromatographic c
44. ur troubleshooting will progress more smoothly if you also have on hand 1 A duplicate analytical column one you know will provide acceptable separation under proper conditions Try this duplicate column in your malfunctioning system If it corrects your problem the problem is related to the original column 2 Anew syringe to help isolate the source of ghost peaks Repeat the analysis with a new clean syringe If your trouble disappears the problem is isolated to a defective or dirty syringe used during the original analysis 3 Leak detection aids Use these to ensure that your entire system is free of leaks as is mandatory for proper operation We strongly recommend using electronic leak detecting units rather than liquids 4 Spare septa and high temperature septa These help to identify problems with reproducibility or ghost peaks caused by a leaking or bleeding septum Replace your septum with a new duplicate septum or with a higher tem perature septum If the symptom disappears the trouble was a leaking or bleeding septum SSUPELCO T109792C 5 Detector cleaner A dirty detector creates noisy baselines Flame ionization detectors FIDs can be cleaned by using either Freon TF an in place cleaner or an ultrasonic bath filled with an immer sion cleaner 6 Thermometer To verify the oven temperature ruling out defective tempera ture control 7 Spare ferrules To eliminate leaks in connections
45. y Use correct syringe size use solvent flush technique see pages 3 and 4 Check correct if necessary Inject standard for comparison Use new syringe Replace septum Increase injection port temperature Measure flows correct if necessary Replace air tank Clean collector spring clip with emery paper Clean per instrument manual a Measure flow adjust if necessary see page 2 b Refer to instrument manual Use deactivated column materials Check with hydrocarbon free standard change to column that will separate hydrocarbons from components of interest Measure flow adjust if necessary see page 2 Check for leaks correct if necessary see page 3 Increase column temperature Verify column temperature and stationary phase temperature limits Analyze sample on known good column Repack first 6 of column or replace column SUPELCO Bulletin 792 Symptom Retention times correct Components with longest retention times show low values when using normalization techniques Retention times correct Different components not yielding similar peak areas for same amount Quantification varies for one compo nent eluting over wide time span even using internal standard technique Inconsistent quantification for same sample on successive analyses Low values for minor compounds Increased peak response with successive injections Symptom No 6 Baseline OffScale Cannot Zero F
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