RE: Temperature calibration

Keith Brown (brownk@chem4823.usask.ca)
Fri, 30 Apr 1999 11:43:36 -0600 (CST)

Many thanks to all of those who replied to my query concerning our
temperature calibration problems. I believe that I have discovered the
source of the problem and would like to share it with you.

As you will recall, we were getting readings for methanol that when
compared to the calibration table generated by the NMR Temperature
Measurement web page at
http://bmrl.med.uiuc.edu:8080/mrtools/nmrtherm.html were consistently
12-15 degrees too low. There were many concerns about the purity of the
methanol however, even using a decidedly fresh, pure sample we were
*still* getting these whacky results.

The solution to the puzzle was to look carefully at the generated
calibration table from the web page. It doesn't work! The equation given
on a related page http://bmrl.med.uiuc.edu:8080/mrtools/nmrt_ref.html *is*
good but its implementation in the generator program isn't. Rather than
use the generator program I am now using the equation in a spreadsheet.

Also, I learned that there is an au program called calctemp for doing
the temperature calculation based on the chemical shift differences of
methanol or glycol and received a copy from Bruker (many thanks!). If
there is any interest I'd be glad to post it to this list for you to cut
and paste ...

Keith Brown
University of Saskatchewan
Saskatoon, Saskatchewan

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