Hi AMMRLers,
First of all I want to thank everyone who responded to my previous
e-mail asking for their experiences on frequent exchanges between
cryogenically cooled probes and RT probes. Several people were
interested in hearing what the community has to say about it, either as
general knowledge or to help them plan their next purchase. Here is a
summary of the responses:
1) The general advice is to have a dedicated instrument for your
cryogenically cooled probe. These probes seem to work quite robustly
once they're running and undisturbed.
2) In the case you don't have this luxury, contact your probe
manufacturer and ask for their recommended number of swaps per year.
Our probes are Varian and their recommendation was 4 swaps per year,
that is, every three months or so.
3) The thermal cycle a cold probe undergoes seems to be the cause of
most problems. Several people have observed probe failure during the
cooling cycle due to stress in the electronic components.
4) Failures in vacuum pumps, water chillers, power blinks, and other
unplanned events force you to have more thermal cycles than you want.
Therefore, the more you exchange your probe the more likely something
can brake.
5) Installing, conditioning, and testing the cryogenically cooled probe
requires 24-48hr. Depending on your facility needs, this can be a
considerable amount of down time.
Hope you find this information useful.
Later
________________________________________________________
Dr. Carlos A. Amezcua
Biomolecular NMR Manager
University of Texas Southwestern Medical Center
Biochemistry Department
5901 Forest Park Rd.
Dallas, TX 75235-8816
ND8.910
Tel: 214-645-6380
http://utswbionmr.swmed.edu
Received on Fri Sep 02 2005 - 14:41:16 MST