Basic Bruker Proton NMR Tutorial

Liquid Samples


Instrument Startup, Optimization, and Shutdown


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INSTRUMENT STARTUP:

Note: if there is a sheet of paper attached to the monitor which says 'Experiment in Progress' or something similar, contact your laboratory instructor before proceeding.

Check the NMR Log Book! You must make an entry in the Log Book when you are operating the NMR. Include the date, time, your name, where you're from and what sample you ran or what you did on the instrument. If you find any problems with the instrument, note them there. The Log Book is meant to record everything that gets run or done to the instrument, and is very useful for tuning and maintenance purposes. It must be kept up to date.

INSTRUMENT LOG-ON:

Users must log-on to the system before running the NMR. After log-on, start the main NMR program by typing 'xwinnmr' at a UNIX prompt. Load the experimental parameters you need by typing 'rpar' at the Xwinnmr command prompt and selecting the experiment from the displayed list. Experimental parameters will be chosen by your laboratory instructor and stored with a unique name.

SAMPLE SPINNING:

Press the 'Spin On/Off' button on the NMR control pad. The sample should begin spinning. Press the 'Spin' button on the NMR control pad to monitor the actual spin rate. The spin rate can be changed by turning the large knob on the control pad. Set the spin rate to 20-30, which should be OK for most experiments.

SIGNAL LOCKING:

At the Xwinnmr command line, type 'lockdisp' and press Enter. A window will open which displays the signal lock in real time. At the Xwinnmr command line, type 'lock cdcl3' and press Enter. Wait for a couple of minutes while the instrument locks automatically on CDCl3. Note that other solvents can be used instead of CDCl3, and the lock command needs to be issued with the appropriate solvent name.

INSTRUMENT OPTIMIZATION:

At the Xwinnmr command line, type 'wobb' and press Enter. Now type 'acqu' and press Enter. This initiates the probe tuning mode and switches to the acquisition screen so you can see the tuning signal in real time.

The tuning signal should be sharp and centered on the reference line in the center of the screen. If not, you'll need to tune the probe for your sample. If the probe needs tuning, get help from your laboratory instructor.

At the Xwinnmr command line, type 'stop' to exit probe tuning mode.

CHECK THE SHIM SETTINGS

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PROGRAM SHUTDOWN AND LOG-OFF

Click on the Xwinnmr 'File' menu and choose 'Exit'. Click 'OK'.

Click on the 'Desktop' menu and choose 'Logout'. Click 'Yes' to log-out.




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