I am Dr Derek Kennedy on derek_kennedy@merck.com. Although an American port I
am in fact based at Merck Sharp and Dohme, one of the UK sites of Merck Inc. I
run the nmr facility for a smallish organic chemistry development group, and we
have: DPX250 with a single 5mm 1H/13C dual probe on open access - no sample
changer or vt. 'My' machine is a DRX400 with vt, and single axis gradients,
again no sample changer. The probes available are a qnp 1H/13C/31P/19F and an
inverse broad band gradient probe. I tend to use the inverse probe about 80%
of the available time. My current flavour of the month is 1H/15N hmbc using
40-50 mgs compound on an overnight run. I use only 32 increments, but for now
that is adequate for the compounds under study. I plan to extend hmbc here to
1H/11B to look at borohydride reduction systems some time this year.
I have had one little known problem with the inverse probe, when tuned to 15N a
wobb on 1H showed two!! minima, neither of which could be tuned. To overcome
the problem (harmonics??) I changed the decade tuner rods in the third digit by
one, ie 7726 became 7716 and then rematched,retuned,rematched... to a good
wobb. A repeat wobb on 1H showed no problems at all. I also have broad band
noise from approx. 40 to 80 Mhz! I await events from Bruker.
I look forward to hearing from any of you.
Kind regards
Derek.