All:
ORIGINAL QUESTION:
We have been having a sample breakage problem the last couple of weeks. Its
very intermittent and occurs with different students/different tube brands,
etc. For instance, a student inserts a sample, has trouble
locking/shimming/spinning, and then ejects the sample. They find that their
sample has broken. When I get on the scence I remove the probe and take a
look. In each case the tube breaks at the top of the probe. The tube remains
intact inside the probe. In the past 2 weeks we've had 4 of these breakages.
No changes were made to air/spinner/probe/etc prior to these occurances.
I marked a tube with black ink and checked for scoring marks. A scoring mark
appeared around the same place where the breakage occurs with repeated spin
on/spin off, as I suspected. I realigned the probe and the upper barrel,
however, samples are still breaking.
It seems to me it has to be an air problem. The sample must break when the
spinning begins rather than hit the bottom too hard. Anyone have a
suggestion to trouble-shoot this problem?
---------------------------------
Thanks for resonding to my NMR tube breakage problem. As most of you
guessed, yes, we are using Varian systems. When I was adjusting the
bearing air, I noticed an air leak. It turns out there was a leak in the
seal on the Baliston filter tube in the magnet leg. This was probably the
culprit all along. Rather than purchase a new filter from Varian, we
resealed it with JB Weld. At least I had an excuse to clean the upper
barrel! I also replaced the spinner. So far, no broken samples...
Regards,
Tanya
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Tanya L. Young, Ph.D.
Senior Scientist
Department of Chemistry
Kansas State University
Manhattan, KS 66506
office: CB 128
phone: 785-532-6477
email: tyoung_at_ksu.edu
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Received on Mon Jul 07 2003 - 09:36:52 MST