Dear Charlie,
the only large diameter cryoprobes we have built are all X-observe. We have
10mm 13C/1H dual probes and for very high fileds we have built some 8 mm TXO
probes that are optimized for 13C or 15N. 8 and 10 mm probes will suffer
greatly from almost any level of salt concentration.
I do remember the time back in the 90's when we built 8 mm conventional HCN
probes only to be disappointed by their performance. They took about 3 times
the volume and as soon as there was salt or buffer in the solution you were
lucky to get 60% more signal than the 5mm probe.
The problem is only going to get worse with cryoprobes or at higher fields.
Sorry for the bad news but there is no magic bullet here.
Regards
Clemens
On 10/28/2024 14:34, Charles Fry via groups.io wrote:
Hi all,
I’m supporting a protein research group that needs to work at low
concentrations (20-50 uM) and is asking about using a 10mm cryoprobe. I’ve
talked about line shape and shimming on such probes, and also mentioned 8mm probes.
I’m uncertain about how bad Q-spoiling by buffers might be. I’ve used
X-direct-detect 10mm probes, but have only talked with vendors about 8mm probes and
those discussions were at least 10 yrs ago. What I recall is that 5mm probes are
better optimized for both line shape and sensitivity, and that overcomes (at least
most of) the advantages of larger sampling volume with the bigger diameter probes. But
I’ve always wondered how much the economics of such expensive devices -- a
larger diameter probe having considerably narrower utility -- might influence such
discussions. One aspect is whether new shimming technologies might make the larger
diameter probes more competitive than they used to be?
The research group remains interested in the possibilities. I agreed to ask=
in this forum who might have such probes, especially those that would be open
to outside academic use. Even if you have a probe that is not available for use
to others, it would be great to hear more about their utility for 1H- and
13C-detected 2D and 3D experiments.
Cheers,
Charlie
--
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Clemens Anklin Ph.D. Vice President
Bruker BioSpin NMR Applications & Training
15 Fortune Drive NEW Phone: 978-313-5NMR(5667)
Billerica MA 01821 twitter: _at_canklin
web: http://www.bruker.com
e-mail: clemens.anklin_at_bruker.com<
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Received on Tue Oct 29 2024 - 06:12:25 MST