TCNJ Chemistry Instrumentation

Operating Instructions

Varian Gemini 300MHz NMR

1) Log onto the computer (username: student, password: chemist1). Click on the button that looks like a spectrum to open the NMR software.

2) Click on "acqui". This opens a separate window for locking and shimming.

3) Click "eject" to eject the standard from the instrument.

4) GET UP and put your own sample into the instrument.

5) Click "insert" to insert your sample.

6) Click "Lock" to bring up the lock screen. Make sure that spin is clicked to "on". Turn the lock "off", and then find the lock signal by adjusting Z0. Adjust the power and gain so that the signal is at a reasonable size. Once the signal is locked onto a single "wave", click lock "on".

7) Once the signal is locked, click on "Shim". Maximize the signal with Z1 and Z2 course and fine; adjust the power and gain as necessary by clicking on "Lock" to return to the lock screen.

8) Once shimming is done, click "close".

9) Now click "Setup", and then choose the appropriate solvent and nucleus. For 1H spectra in CDCl3, simply click the appropriate button. More "exciting" solvents and/or nucleus combinations can be selected by clicking the "other" button.

10) Click "Acquire", followed by "Go, Periodic WFT", or simply type "ga" to acquire the actual spectrum.

11) Once the spectrum appears (the computer will beep at you in glee), type "aph" to phase the spectrum.

12) Type "dscale" to bring up a scale in ppm.

13) Left-clicking in the spectrum will bring up a red cursor, and right-clicking will bring up a second cursor. The two cursors can be moved simultaneously by dragging with the left mouse button, and the right cursor can be moved alone by dragging with the right mouse button. If desired, the spectrum can be expanded to fill the screen by bracketing the desired area with the cursors and then clicking "expand". Note that the cursors can only be brought up in "interactive" mode (see below).

14) Click "th"; this brings up the yellow (horizontal) threshold bar. Drag it up or down with the left mouse button to the desired level as a lower limit for assigning peak frequencies.

15) Type "dpf" to display the peak frequencies. Go back and change the threshold as in step #14 if you get a zillion peaks.

16) To integrate, click on the "Part Int" button. This should bring up a green integral line. Then click "Resets". Now use the left mouse button to cut the integral at the appropriate locations. The right mouse button can be used to "patch up" mistakes. It will reattach preciously cut integrals piece by piece if you wish to go back and correct a mistake.

17) Type "VP=12". This raises the spectrum vertically to make room for numerical integral values.

18) Type the sequence "pl pscale ppf pir page" (pl=print spectrum, pscale=print scale, ppf=print peak frequencies, pir=print integrals, and page sends the whole thing to the printer).

19) If desired, the integral values can be scaled to a certain reference integral (i.e., an aromatic proton can be set to a value of 1.00, a methylene group to 2.00, etc.). To do this, click on the integral in question to bring up a red cursor on top of it (this must be done in interactive mode), and then click the "set int" button and enter the desired integral value.

20) When you are done, click on "acqui" again, eject the sample, and reinsert the standard. Lock the signal for the standard, and then click on the following sequence of buttons: "Main Menu", "More", "Exit VNMR". Then click the "Exit" button (bottom of the screen). Click "OK" when prompted. Note: If you do not see the Exit button, right click and choose "Log Out". Do not shut off the monitor. Just walk away with you spectrum and sample in hand and a smile on your face.

**If you ever lose your place in the NMR software, click on the following sequence of buttons: "Main Menu", "Display", "Interactive". This will get you back to interactive mode.**