Hello all!
Having done most of my work in CDCl3 or D2O, I have observed some
interesting effects by using d6-DMSO! Have any of you an explanation
for why I can acquire lovely standard 13C and DEPT-135 spectra of a
25 mM ibuprofen sample in CDCl3 quite easily (great S/N with few
scans) whereas if d6-DMSO is used, there is literally no analyte
(ibuprofen) signal in either experiment (under identical conditions-
with tuning and matching done for both samples)- not even in the DEPT
135? I do notice a small effect on the 1H-NMR relative sensitivities-
d6-DMSO giving a slightly lower S/N than that in CDCl3, but the
effect in the 13C-NMR is dramatic.
Any ideas and explanations? Viscosity could affect such a change, but
it would/should be more noticeable on 1H and not 13C NMR. We see this
phenomenon with non-hydrogen-bonding capable analytes as well.
Any clues?
Thanks in advance!
Paul
Paul Shin, Ph.D.
Department of Chemistry and Biochemistry, CSUN
California State University
18111 Nordhoff St
Northridge, CA 91330
818-677-6887 phone
818-677-4068 fax
www.csun.edu/chemistry/Facilities.html
Received on Tue Oct 23 2007 - 10:14:15 MST