I guess I'm the anal retentive one of the bunch. My users are not only =
required to lock on the standard (1,4 dioxane in CDCl3), but they have =
to run an quick, automated macro (borrowed from the "c13res" Varian =
macro), which does one decoupled C13 scan, and displays the peak and the =
linewidth. If they can't get < 0.3 Hz FWHH, then they have to let me =
know immediately.
This is my way of making sure the most basic things are working right =
(1H/ 13C probe tuning, X-transmitter, Decoupler power/modulation -- H2 =
is set about 3,000 Hz off resonance, so it really shows if power/Garp1_6 =
mod-freq. aren't matched --, shims...etc.).
Many of my users change probes on the fly, and most of my users =
regularly re-tune for 31P, 19F, 29Si, 119Sn,...etc, so this is a good =
way to be sure that the standard condition (ready to go for 13C/1H in =
chloroform using the 5mm BB probe) is met before they log off. =
Initially, this seems a hassle for them, but with practice it only adds =
about 2-3 minutes to their time if all goes well. =20
The only exception to this is our Nic-Tecmag 360, which _only_ does =
proton. On this one they just shim on a CDCl3 sample and leave (the =
average expt. time is 3 minutes per spectrum on this beast)...and the =
solids instrument, which .. of course...doesn't lock on anything 8-)
----
Richard Shoemaker, Ph.D. Phone--(402) 472-6255
Instrumentation Director, Chemistry FAX---- -6964
Research Associate Professor, Chemistry
University of Nebraska-Lincoln =20
URL: http://www.chem.unl.edu/nmrlab.html =20