Tracy,
I've seen trouble with solvent mixtures involving students making up the mixture
in the nmr tube. They pipette the second solvent on top of the first and don't
then do adequate physical mixing. Weird time dependent things happen. Ejecting
the tube and inverting shaking etc revolves the problem. Maybe that's the issue here?
Charlie
On Jan 12, 2024, at 1:07 PM, Zhang, Tracy Chunxin (GE Aerospace, US) <zhangc_at_ge.com> wrote:
Dear all,
I have run into an odd issue here: one of the chemists using my walk-up instrument,
a 500MHz Bruker Avance III, said she had trouble locking her sample in a DMSO-D2O
mixture (80/20) in ICON. When I tried to run it manually, you can see the lock
signal (we used to call them “rabbit ears” in grad. School) sweeping
in the lockdisp window when you first dropped the sample in the magnet, but a few
seconds later, the lock signal turns into flat noise and the sample would not lock.
A D2O, DMSO, and DMSO/D2O (80/20) standards all worked fine. The sample worked fine
on our Agilent 600MHz NMRS. The chemist could not think of anything in her sample
that might have possibly caused the problem. Just wonder if any of you have seen
something similar and if there is a work around. We would prefer for her to be
able to run her own samples on the walk-up instrument. Thank you!
PS—Wish I could attach the short video of the disappearing lock signal,
but our firewall blocks any external email attachments. ☹
Tracy Zhang, PhD
Analytical Chemist
GE Aerospace
T +1 518 387 7642
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Received on Fri Jan 12 2024 - 10:50:43 MST