UNIVERSITY OF WISCONSIN River Falls
Note: Where the instructions tell you to type a command, only type what is within the quote marks, do not type the quote marks.
1. Prepare sample in a precision sample tube.
2. On the keypad, turn off the "Lock on/off" (light should be off)
3. Turn off the Spin On/Off
4. Turn the "Lift On/Off" to on, retrieve sample holder, insert the new sample tube, check depth gauge, wipe tube with a kimwipe and place on top of the probe. Turn "Lift On/Off" to off.
5. Press "Spin", the light should blink. By pressing second function, and Spin Meas. the keypad will display the preset spin rate (20 Hz) and the actual spinning rate of the sample tube. When the actual rate reaches the preset value, the light will stop blinking.
6. Press "Standby".
(All mouse clicks are done with the left mouse button unless otherwise specified.)
1. If the computer is not already running:
Log on with username "student", password "chemnmr".
Start XWin NMR by double-clicking on the icon on the desktop.
LOADING A PRE-EXISTING SET OF PARAMETERS
1. Pull down the "File" menu, move to "open" and release on "data set owners".
2. Click on `nmr" or any other data set owner given to you by your instructor.
3. Pull down the "file" menu, move to "open" and release on "data sets by name".
4. Click on "stdproton" or any other data set that your instructor has directed you to. Old data may be displayed. Ignore it.
5. Pull down the "file" menu, move to "new" and release. Click in the box after "name" and type in a new name for your sample. Be sure to click in the box after "user" and to type in your owner name. Then click on "save". You are now set up to collect a standard 1D proton spectrum.
LOCKING AND SHIMMING
1. Type: "lock" (return). A list of solvents will be displayed. Click on the solvent being used in your sample.
2. Pull down the "windows" menu and release on "lock". A window with green and white wave patterns moving across it will appear. This can be made larger by clicking on the upper right hand corner box.
3. The instrument will have already automatically locked on to the deuterium signal in your sample. If it has, the light on the "Lock" button on the keypad will be lit. If it has not, press "Autolock". This button will blink for a while, and eventually the "Lock" button light will come on and stay on. During this the red and white wave patterns will move up on the lock window display.
4. On a spinning sample there are only two shims to use, Z and Z2. Press Z and adjust it by turning the knob on the keypad in whichever direction causes the red and white wave patterns to rise vertically in the lock window display. If adjustment causes the patterns to move off the top of the screen, press "lock gain" and use the knob to bring them back down onto the screen. Then press Z again to continue shimming. If an adjustment in Z only leads to a worsening, by pressing Z a second time you will return to the original value at which you started. Pressing any other key will cause your most recent adjustment to be saved. Alternately press Z and Z2, adjusting each until no improvement in the vertical position of the lock signal can be obtained. Press "Standby" and click the box to shrink the lock window. Click on the main window to bring it to front.
RUNNING THE EXPERIMENT
1. Normally the probe is left tuned for proton spectra so that you may proceed with the next step. If the tuning has been changed, another step is required at this point. Obtain the assistance of an expert.
2. Type "rga" (return) and wait until the automatic receiver gain adjustment is complete. Display will read: "rga: finished".
3. Type "zg" (return). You can watch the accumulation of the FID by pulling down the "acquire" menu and releasing on "observe FID window". When the experiment is complete, the message at the bottom will display: "checklockshift: finished".
4. Type "ft" (return). The screen will automatically display the Fourier transformed spectrum.
1. In order to adjust the phase well, it is convenient to see the baseline clearly. To do this it is handy to greatly increase the amplitude temporarily. Use the "*2" button to double the spectrum amplitude, and the "/2" button to cut it in half.
2. Increase the amplitude several times as appropriate and then click on "phase".
3. Click on "biggest".
4. Further phase improvement can be obtained by clicking and holding down the mouse button on "PH0" and rolling the mouse up or down as needed. Release when the phasing looks good.
5. Click on "return" and click on "save & return".
6. If you are satisfied with the width of the spectrum you can skip this section. Otherwise you can designate a smaller spectral window and rerun the FID acquisition. The number of scans can be increased at this time, too.
7. To narrow the spectral window, click in the black area of the screen and get an arrow pointing down on the spectrum trace. Click the center mouse button at the left edge of the desired new spectrum width and again at the right edge. The new size will increase to fill the screen display.
8. Click on "utilities". Click on "sw-sfo1" (retrun). The new width is now set.
9. Repeat the acquisition by typing "zg" (return). When the "checklockshift: finished" message is displayed, type "ft" (return) and repeat the phasing process. Click on the "return" button and "save and return".
1. Identify the TMS peak. Left click in the black screen to get an arrow riding on the spectrum. Move this just to the left of the TMS peak and center click. Move the second arrow just to the right of the TMS peak and center click again. A greatly expanded view of the TMS peak will be displayed.
2. Click on "calibrate". Move the arrow until it is riding exactly on top of the TMS peak and click the center mouse button. Type "0" (return). Click the left mouse button to regain the usual cursor arrow. Click on the restore full spectrum button (third down on the right column of buttons).
1. Click on "integrate".
2. Click on the screen to get an arrow riding on the spectrum trace.
3. Click the center mouse button to the left and right of peaks that are to be integrated separately. When finished, click on "return" and "save and return".
1. The plotted spectrum can display numerical labels for the chemical shifts of selected peaks. Usually only the tallest peaks are wanted for labeling. The threshold is set by clicking on "utilities" and then on "MI". (Click "ok" on any error messages that appear.)
2. Obtain a horizontal line that moves up and down with the mouse. Adjust it to the desired height and click. Click on "return".
1. Type: "setti", (return). Obtain a new window, position it and click to make it active. Position the cursor in the gray area and type the desired title for the spectrum.
2. Click on "save" and the "quit".
1. Pull down the "output" menu, move to "define/show plot region", move to "retain CX" and then release. Hit the return key three times in response to the values displayed. Click "ok" on any error message.
2. Type "view" (return). Get a new window, position it with the mouse and click to make it active. Click "ok" on any error messages. Click on quit to remove the preview.
3. Type: "plot" (return). Click "ok" on any error messages.
IMPORTANT: Be sure that there is a sample in the magnet when you leave the instrument. You may leave your sample in if you do not need to recover it, or you may put in a standard sample. After putting a sample tube back into the spinner, release the lift button on the keypad. You may also turn on the spinner. Do not leave the magnet with the lift air on and no sample in.
REMOVING THE SAMPLE
1. On the keypad, turn "Lock on/off" to off. (Light goes off.)
2. Turn spinner off. (Light off.)
3. Press "Lift" (Light goes on.)
4. Retrieve sample from spinner.
5. Replace a sample tube in the spinner, return this to the magnet and turn the "lift" button on the keypad to off.