Troubleshooting Acquisition Related Problems
Contents
1. Reduce the lockpower by 20 and find the lock signal If you see the signal with bumps reduce lockpower will cause all resonances to further be excited This makes locking on a single resonance difficult Lockgain is too low The signal from your Increase Lockgain to sample is not amplified maximum enough for you to see the signal Ifthe above table does not resolve your problem try locking on a pure sample of CDe Once you are able to lock on the benzene ds shim as well as you can Replace the benzene ds sample with your sample and attempt to lock Still can t get a lock Contact the staff at 792 I Can t Access a Workspace e g exp1 exp2 The usual message you will get is foreground processing is active A locked experiment is a result of improper logging off by a user Remember to always exit VNMR prior to exiting the User session To unlock and gain access to an experiment Type unlock force where is the number of the locked experiment For example I try to access exp by typing jexp1 and I get the foreground processing is active message I would then type unlock 1 force Expl is now available I Can t Eject my Sample This is usually a result of a failure in the acquisition computer You need to see if the acquisition computer is active 1 Look at the ACQUISITION STATUS window and see if the Status is Idle Acquiring or Inactive2. click off then click on If it still is not spinning then The most common cause of this problem is a dirty spinner or an improperly gauged sample 2 Eject the sample and clean the spinner with a Kim wipe and ispropanol Make sure you clean the narrow portion of the spinner 3 Regauge the sample IMPORTANT Always hold the spinner and sample at the fat part of the spinner Holding the sample and not the spinner may cause the spinner to slip which will make shimming difficult 4 Insert the sample If it still does not spin contact the NMR staff 792 or leave message at 386 or 387 Please fill out a NMR Incident Report
3. for various instruments 4 Push the reset button IF YOU ARE UNSURE PLEASE CONTACT STAFF LOCATION OF RESET BUTTON FOR EACH INSTRUMENT Instrument floor Reset Button Location Open the left door of the big grey console Anubis amp Mut UPlus 500 sb B 7 B 8 and look for a red button in the middle right In the grey box to the left of the computer open the left door and look for the hand Ra Inova 300 sb written blue arrows to the middle left The red button below reset at the far left where the blue arrows point is the button Open the door of the box to the right of the Hathor G 300 5th computer Look for the switch with the hand written word reset Open the left door of the big grey console Maat amp Imseti UnityPlus 300 2nd and look for a red button in the middle right Khufu Inova 300 2nd Open the left door of the box on the wall with windows Look at the middle left and just above the blue plug The small white button above the letters RST is the button Nn After pushing the reset button wait for at least 40 seconds 6 In the terminal window type su acqproc and hit Return This will take a few moments Look at the ACQUISITION STATUS window in VNMR Wait for STATUS to read idle 7 Inthe VNMR command line i e where you usually type e type su and hit Return The NMR should now be ready for use 8 For VXR 500
4. If the proceeding procedure did not work repeat the above procedure but instead of pushing the reset button flip the switch directly below the reset button to off Wait about 20 seconds then switch it to on Follow Steps 4 6 Can t Lock on Sample This can be caused by several problems Common reasons and their solutions are listed below Common Reasons for Inability to Lock Cause Result Solution No deuterated solvent No deuterium signal to lock on Use a deuterated solvent like CDCl Shimming is very poor The signal is so broad that it is not well observed Type fixshims to get a good Start Suspended particles This causes line broadening which makes the signal intensity weaker Filter your sample Too concentrated There is little deuterated solvent to get a lock Especially problematic when using CDCl Dilute your sample or use a solvent with more deuteriums e g C6D6 Improperly gauged When injected the sample is not in the coil Eject sample and ensure that the sample resides between the white lines on the gauge Lockpower is too low The sample is not receiving enough rf signal to flip the deuterium spins Increase lockpower to 80 of max before trying to lock Lockpower is too high for multi resonance samples With solvents having more than one deuterium resonance e g CD30D THF ds high lock power
5. Troubleshooting Acquisition Related Problems This handout contains pertinent information to help you when a problem arises Please look through the topics below to identify and find resolutions to the most common problems at our facility If your problem is not listed please contact the staff at 792 or leave a detailed voice message at 386 Kermit or 387 Dan In addition please fill out our NMR incident report so that we may be better able to serve your needs The incident report should be used even if you are able to fix the problem Broken Tube in the Magne THIS MUST BE REPORTED AS SOON AS POSSIBLE TO MINIMIZE DAMAGE TO THE PROBE DO NOT ATTEMPT TO REMOVE THE SAMPLE PLEASE CONTACT NMR STAFF IMMEDIATELY CALL 792 386 OR 387 IF THE STAFF IS UNAVAILABLE PLEASE LEAVE A MESSAGE AT 386 OR 387 ALWAYS LOG OFF OF THE INSTRUMENT AND HANG A SIGN ON MONITOR STATING BROKEN SAMPLE DO NOT USE INSTRUMENT Console is unresponsive to Commands 1 With the right mouse button click once on the Solaris desktop background to reveal a menu Click on Programs or Tools then over to select Terminal A Terminal window will pop up 2 Inthe Terminal window type su acqproc and hit Return You will get a message indicating that acqproc is being killed Also in the ACQUISITION STATUS window in VNMR STATUS should now read inactive 3 Proceed to the NMR console which is the big grayish box See below for location of reset button
6. a Ifit is Acquiring type aa If you get the message similar to no experiment is active you will need to reboot the acquisition computer Use the procedure for an unresponsive console on page 1 b If it is Inactive you will need to reboot the acquisition computer Use the procedure for an unresponsive console on page 1 c If itis Idle try typing exit Wait about 1 minute If you are not exited from the VNMR program you will need to reboot the acquisition computer Use the procedure for an unresponsive console If you are exited click on the VNMR icon and type su then try ejecting again Still can t eject Try to reboot the acquisition computer Use the procedure for an unresponsive console If rebooting does not work contact the NMR staff at 792 Poor Shimming Poor shimming or more properly poor line shape can be a result of many factors Below is a list of common causes and their remedies Common Reasons for Poor Shimming Cause Result Solution No deuterated solvent No deuterium signal to lock on and thus nothing to shim on Use a deuterated solvent like CDCl Initial shimming is poor Your peaks are very broad Type fixshims to get a good Start Suspended particles This causes line broadening which makes the signal intensity weaker Filter your sample Too concentrated Concentrated samples can be viscous which will cause line broadening Dilute your
7. rrect experiment e g Setup gt C13 CDCI3 for carbon and type su after setup Be sure to carefully follow the instructions on the magnet Do NOT force the tuning rods They are FRAGILE If you feel resistance when turning the rod you probably have reached the end and should turn the rod in the opposite direction Always start tuning by turning the shorter rod Red for Proton Gold for Carbon In general you need only turn the shorter of the two rods for either Proton or Carbon Ifyou need to turn both rods start by turning the shorter one until you get a minimum on the meter Then a Turn the longer one Blue for proton Black for Carbon in a direction opposite to what you turned the short rod Turn the long one to the minimum and continue turning in the same direction until the meter reading goes up a bit 5 with the lower knob set to 60 b Now turn the short rod to minimize the meter reading and continue turning in the same direction until the meter reading goes up a bit c Return to the long rod and turn to minimize Turn past the minimum as before d Repeat for both the short and long rod until the meter reading is minimized e If this process does not lead to a minimum try reversing the directions you were turning the rods The Temperature is too High Low Type temp 25 su This will reset the temperature controller to 25 degrees Celsius If this does not work type vttype 2 su temp A new window will pop
8. sample Too little solvent When injected the sample is not properly positioned in the coil and the liquid air interface is seen by the coil This will make shimming very difficult Add more solvent Improperly gauged When injected the sample is not properly positioned in the coil and the liquid air interface is seen by the coil This will make shimming very difficult Eject sample and ensure that the sample resides between the white lines on the gauge If shimming problems are not resolved contact the NMR staff at 792 Poor Signal Noise Signal Noise S N improves as the square root of nt Increasing the number of scans will improve S N up to a point Maximum improvement in S N occurs early in the experiment Diminishing returns are achieved with larger number of scans Increasing concentration is an obvious fix if you have enough sample But be careful not to get too concentrated because line broadening will occur at higher concentration Many of the same problems with poor shimming result in poor signal noise If you don t get better S N after trying the shimming procedures contact the NMR staff If you are using either of the 500 s make sure that the probe is tuned correctly The tuning procedure is posted on each magnet and available as a handout Some hints are listed below Tuning the 500 s Anubis amp Mut rooms B 7 amp B 8 Be sure that you setup the co
9. up Adjust the temperature on the slider bar If the temperature is still incorrect contact the NMR staff at 792 The VNMR Screen Colors are Terrible The odd colors for your VNMR interface are usually a result of having too many windows applications open Since VNMR is generally the last to be opened it is given the last dregs of color available which turn out to be pretty awful You should close all unnecessary applications prior to running VNMR TO FIX THE DISPLAY COLORS OF VNMR 1 After logging in to the session and prior to running VNMR close all windows that pop up e g Netscape Solaris Registration Terminals etc a Ifyou have the Solaris Registration window open every time you login you can disable it by clicking More Information gt Never Register gt Never Register 2 Click on the VNMR icon The colors should be fine If not or if you want your own colors do the following a Type color A color palette will appear b Click on the button for the item you wish to change the color e g background spectrum etc and then click on the desired color c When completed enter a filename for the name color scheme and click save If you want this new scheme to be the default save the file as DEFAULT My Sample is not Spinning 1 Check to make sure that spin is turned on by clicking Acqi gt LOCK Check the spin setting at the bottom of the window o Adjust the spin rate to 20 To the right of Spin
Download Pdf Manuals
Related Search