NMR Spectrometer Crib-Sheet

Transcription

1 NMR Spectrometer Crib-Sheet Sample Preparation: 1. Dissolve your sample in a deuterated solvent. For 1 H NMR use ~ 1 mm concentrations. For 13 C NMR, use ~ 10 mm. 2. Use clean dry tubes to avoid contaminating the sample. (Recommended tubes: 5 mm for 1 H, 10 mm for anything else.) 3. Filter the sample solution. (One is easy filtering method is to drip your solution through a pasteur pipette equipped with some glass wool in the bottom and some MgSO 4 straight into your NMR tube.) 4. Always use a 4-cm solution height. 5. Use the depth gauge to poisition the sample tube correctly in the spinner. 6. Make sure both the sample tube and spinner are clean before inserting into the magnet. Logging in and Starting the Spectrometer 1. Log into the spectrometer using your login name and password. 2. Open a UNIX shell by going to Desktop and selecting Open UNIX shell. Type xwinnmr into the UNIX shell. 3. When the program opens up, type edc. A window will open up which lets you give the name, experiment number, and processing number to your data set. Other information is the area on the disk where the data is saved, the owner of the data, and the data type. Enter the name, and if you are doing another experiment on the same sample, change the experiment number. You should enter your login name as data owner. Press save. 4. Type ej. When you hear the compressed air, put your sample into the magnet. Type ij to lower your sample into the magnet. General Notes 1. When you want to zoom in on a peak, click on the left mouse button to activate the cursor. Use the middle mouse button to select the left and right limits of expansion. Finally, click on the left mouse button again to free the mouse.

2 1H NMR 1. Type rpar PROTON all. (This reads in generic parameters for a proton experiment). If necessary, tune the probe. (See probe tuning section. In general, this need not be done, and should not be done without Dr. Gaede's permission.). 2. Type rsh. A table will come up with different shim files. Select one which has both 5mm (if you are using a 5mm tube) and the name of your solvent in the name. 3. Type lock. A window will pop up with solvents. Select the solvent you are using. 4. Type tune. A window will come up with some routines for further shimming your sample. Choose the file named example. (*Note: You can get an idea of the quality of the shimming by observing the lock signal -- go to window and choose lock. If you are not satisfied, you can improve the shimming futher by adjusting the Z, Z 2, and Z 3 shims. Press the corresponding button on the keypad and turn the knob to maximize the lock signal. If you ever want to get back to the value you started with, just press the keypad button again. When you are done, press the standby button.) 5. Type edhead. Press Define Current button. If 10 mm Multinuclear is not highlighted, then click on it. Otherwise, just press save. (This tells the spectrometer which probe you are using.) 6. Type eda. First, select the correct solvent. Then click on prosol. (This loads in the correct pulse lengths and powers.when you are done, prosol should say "true".) Finally, save. 7. Type rga. This adjusts the receiver gain automatically. 8. Type ased to view all the parameters in the experiment. One you might want to change is NS (number of scans). Use some number divisable by 8.) 9. Type zg. This starts the acquisition. 10. To view the FID type acqu. 11. When the spectrometer is finished acquiring (the message checklockshift: finished will appear in the lower left hand corner of the window), type ef. (This multiplies your FID by an exponential function and then Fourier transforms it.) 12. To phase your spectrum, click on the phase button. Click on the biggest button. This selects the biggest peak for you to perform zero-order phase correction. Now click on the PH0 button and hold the mouse button down.. While holding the mouse button down, drag the mouse to adjust the phase so the baseline is even on either side of the biggest peak. Now click on the PH1 button and hold the mouse button down. While holding the mouse button down, drag the mouse up or down to adjust the phase of some peak far away from the biggest peak. 13. Click on the return button and then the button save and return. 14. Type abs. (This automatically corrects the baseline and chooses regions for integrals.)

3 13C Spectrum --Decoupled 1. Type rpar C13CPD all. (This reads in generic parameters for a decoupled carbon experiment). If necessary, tune the probe. (See probe tuning section. In general, this need not be done, and should not be done without Dr. Gaede's permission.). 2. Type rsh. A table will come up with different shim files. Select one which has the name of your solvent in the name. 3. Type lock. A window will pop up with solvents. Select the solvent you are using. 4. Type tune. A window will come up with some routines for further shimming your sample. Choose the file named example. (*Note: You can get an idea of the quality of the shimming by observing the lock signal. If you are not satisfied, you can improve the shimming futher by adjusting the Z, Z 2, and Z 3 shims. Press the corresponding on the keypad turn the knob to maximize the lock signal. If you want to just get back to the value you started with press the button again. When you are done, press standby.) 5. Type edhead. Press Define Current button. If 10 mm Multinuclear is not highlighted, then click on it. Otherwise, just press save. (This tells the spectrometer which probe you are using.) 6. Type eda. First, select the correct solvent. Then click on prosol. (This loads in the correct pulse lengths and powers.when you are done, prosol should say "true".) Finally, save. 7. Type rga. This adjusts the receiver gain automatically. 8. Type ased to view all the parameters in the experiment. The only one you might want to change is NS (number of scans). Use some number divisable by 4.) 9. Type zg. 10. To view the FID type acqu. 11. Type ef. (This multiplies your FID by an exponential function and then Fourier transforms it.) 12. To phase your spectrum, click on the phase button. Click on the biggest button. This selects the biggest peak for you to perform zero-order phase correction. Now click on the PH0 button and hold the mouse button down.. While holding the mouse button down, drag the mouse to adjust the phase so the baseline is even on either side of the biggest peak. Now click on the PH1 button and hold the mouse button down. While holding the mouse button down, drag the mouse up or down to adjust the phase of some peak far away from the biggest peak. 13. Click on the return button and then the button save and return. 14. Type abs. (This automatically corrects the baseline and chooses regions for integrals.)

4 Spectrum Calibration If you have locked from xwinnmr program, the reference should be set correctly. If you would like to adjust the reference, include TMS in your sample. After you have phased your spectrum, expand the TMS peak using the mouse buttons. Click on the calibrate button. Move the cursor on top of the TMS peak and click the middle mouse button. Type 0. Integration 1. Enter the integrate mode by clicking on the integrate button. 2. Select the areas to integrate by using your mouse button (left -middle-middle-left) 3. Select a particular integral by clicking on it. When it is selected it will be starred. 4. Adjust the integral by clicking on bias and holding the mouse mutton down, adjust the front part of your integral to be horizontal. Adjust the second part of your integral by clicking on slope and holding the mouse button down. 5. In general the commands under current integral will only operate on a starred integral. The command buttons under all will affect all integrals. The commands up top will affect the spectrum. The commands under mouse affect the sensitivity of the mouse. 6. When you are finished, press return and save as " intrng" and return. 7. To get a printout of the integral table, type li. Title and Plotting 1. Type setti and write and store the text you would like to appear in your title. 2. Click on the button dp1 and change F1 to the left limit you want plotted and F2 to the right most limit you wanted plotted. Generally, for 1 H, F1= 10 ppm and F2 = -1 ppm For 13 C, F1 =180 ppm and F2=-1 ppm. Type y to answer the question Change y-scaling on display, according to PSCAL? 3. To edit other plot parameters type edg. 3. Type plot. Tuning the Probe *Note: This procedure should not be done without Dr. Gaede's permission. 1. After you have called in the acquisition parameters (rpar), switch to the acquisition window by typing acqu. 2. Type wobb. 3. A peak will be displayed at the frequency of interest. 4. A correctly tuned probe has a dip at the correct frequency with an even base line on each side. 5. To correct the position of the dip ("Tune the probe") For proton: Turn the tune rod For the broadband channel: Use the special tool to slide the tune bars slowly. 6. To correct the baseline on either side ("Match the probe") For proton: Turn the match rod For the broadband channel: Use the special tool to slide the match bars slowly. 7. Tune and match should be done iteratively. 8. In addition to watching the screen, you can watch the colored lights on the preamplifier. The goal is to minimize the lights. 9. When you are finished tuning, press the button stop.

5 Our spectrometer is capable of doing many more experiments. See Dr. Gaede to get the training you need to receive permission to do them. Last Revision: HCG