Temperature calibration
Keith Brown (brownk@chem4823.usask.ca)
Mon, 07 Dec 1998 09:48:03 -0600 (CST)
I have been doing a few temperature calibrations using neat
methanol in the temperture range 210K - 290K over the past few months. In
August the measurement was completely in agreement with the Bruker
calibration curve ... very linear and with identical slope. In September I
put a new thermocouple in and the measurements do not agree with the
Bruker curve. I get a very linear line when I plot chemical shift
difference versus temperature but with an appreciably different slope from
Bruker's. Is this to be expected when a new thermocouple is used? I
thought that the voltage/temperature characteristics of these devices was
pretty reproducible. Should I be concerned or just use my own calibration
curves?
On a related note, has anyone ever used a methanol-filled capillary
tube as an internal temperature standard? It seems to me that if the
methanol lines don't interfere with the observed spectrum that it might be
a neat way to measure the actual temperature of the sample.
Keith Brown
University of Saskatchewan
Saskatoon, Saskatchewan