Dear BUMs,
We have a phase instability problem on our DRX-600. We first noticed this
as a problem in 2D NOESY spectra. Subsequently we were able to determine
that the phase of a peak in a simple 1D proton spectrum of a standard
sample changed anywhere from 5 to 15 degrees or more overnight. For
comparison, on our DRX-500 the phase variation over 15 hours is much less
than a degree, which is what you would expect. The phase change seems
random in that it may drift one way and then reverse itself and move back.
Bruker originally attributed the problem to room temperature variation but
since the temperature in this room only varies +-0.5C (I track it 24/7)
this does not seem a likely source of the problem. We have swapped out the
frequency synthesizer, RX22, and proton amplifier without solving the
problem. The problem doesn't seem probe dependent as we had it before and
after the recent installation of a cryoprobe on the 600.
Any ideas on what this problem could be due to or suggestions on tests to
run would be greatly appreciated.
Thanks,
Jeff
Jeff de Ropp
NMR Facility
UC Davis
One Shields Avenue
Davis CA 95616
jsderopp@ucdavis.edu
530-752-7677 office
530-752-6480 Lab
530-752-5682 Lab
530-752-3516 Fax
NMR Facility Web site URL is:
http://www.nmr.ucdavis.edu/
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