AMMRLers,
for the last months or so I had an increasing number of NMR tubes show up in our lab which
are too loose in the sample holders. My first suspicion was that our sample holders (Bruker
Kel-F spinners, 13 years old) were worn out, so I replaced the O-rings on all of them. But
that seems not have solved the problem.
Many of the bad tubes have no markings or markings I can not trace to a particular
manufacturer. In one case the tube turned out to be a Wilmad Economy >400MHz tube. I
have so far always trusted Wilmad tubes, but I usually purchased their precision line, which
so far has not given me any of those problems .
I was wondering whether anybody else has encountered similar problems and are there
certain brands or types of tubes you ban from your labs ? I so far required tubes to be rated
300+ MHz, but have not enforced certain brands or banned economy tubes.
Is it conceivable that the problem still could be caused by the age of the sample holders,
despite the O-ring replacement, and that it is time to invest in new sample holders rather than
harrass my users about their tubes ?
I apprechiate any feedback and will post a summary.
Thanks
Holger Foersterling
Received on Wed Jul 06 2011 - 07:14:13 MST