Hi folks. Happy summer!
Question for the masses:
Lately I have been observing anti-phased peaks while doing
proton on our Varian Inova 500. If I use the
chloroform in acetone-d6 reference standard, the peaks appear
12.5 Hz away on each side, usually one up and one down.
I am running SW from -2 to 14 ppm with 8 scans at 45 deg.
I have tried gradients on/off, spinning on/off, lock on/off,
and have even tried different probes, all with no change.
If I do more scans (greater than/equal to 16) the peaks
do get smaller and phase upright, but are still there.
Two weeks ago at the VIVA II NMR symposium the two
thoughts were vibrations from construction or perhaps
helium boiloff flutter from a stuck check valve. I don't
see the same peaks in our 300 that sits 15 ft away,
so I guess this would leave the check valve. I haven't noticed
any change in the boiloff rate, so I assume that the valve is fine.
I did disconnect the line from the check valve and
didn't see any noticeable change in the peaks.
I'm kindof at a loss here. Anyone have good suggestions/ideas
on how to get rid of this nuisance?
Many thanks for all answers/thoughts. -charlie
Charles F. Wandler office phone: (360) 650-2831
WWU, MS9150, Chemistry Dept. office fax: (360) 650-2826
516 High Street
Bellingham, WA 98225-9150
Organic Chemistry Laboratory & NMR Coordinator
email: wandler_at_chem.wwu.edu or Charles.Wandler_at_wwu.edu
Received on Wed Jul 02 2008 - 13:15:09 MST