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Friday, November 21, 2008

Before You Leave .....

This may seem to be a strange post .... a rant really...... but very important.

Over the years I have seen many students start a long acquisition (or series of acquisitions) on spectrometers and then immediately leave the lab. After a long lunch, an afternoon of playing billiards, a good night sleep or perhaps a weekend of skiing, they return to the lab and find no useful data waiting for them.

Why? ......

Well ....... perhaps the spectrometer was set up to run 4 rather than 20,000 scans, perhaps the receiver was saturated, perhaps the recycle delay was set to 1000 seconds rather than 2 seconds, perhaps the pulses were not set correctly, perhaps the spectral width was set too small, perhaps the probe was not tuned and matched, perhaps a delay was set to 10 seconds rather than 10 milliseconds. perhaps a typing error was made in the command to start the acquisition..... etc.

The NMR lab charges you for your time whether you get useful data or not, so it is important to be careful.

Before you leave the lab......

1. Double check the parameters in your experiment and for all queued experiments.

2. Query the spectrometer as to how long the experiment will take ("expt" (Bruker), "time" (Varian)) and ask yourself if the response makes sense.
3. Check the probe tuning and matching.
4. Make sure the receiver gain has been set correctly.
5. Look at the first few scans to make sure you have a signal.

1 comment:

Anonymous said...

This is very useful. I am get used to checking all of these before leaving the lab. I sometimes feel I have got Obsessive compulsive disorder because of doing NMR.