Hi
It might be worth doing a check on the raw s/n of the deuterium channel first
just to check its in spec, also it also might be worth just having a look and
see if the deuterium spectra loom physically reasonable…
All sorts of thing can trash it [bad amplifiers, filters etc]
regards
Gary
Dr Gary S Thompson NMR Facility Manager
CCPN CoI & Working Group Member
Wellcome Trust Biomolecular NMR Facility
School of Biosciences, Division of Natural Sciences
University of Kent, Canterbury, Kent, England, CT2 7NZ
01227 82 7117
g.s.thompson_at_kent.ac.uk
orchid: orcid.org/0000-0001-9399-7636
On 20 Jan 2025, at 09:33, Gary Thompson via groups.io wrote:
Of course a check if s/n on the deuterium channel would be a good idea as well
> From: main_at_ammrl.groups.io on behalf of Anklin, Clemens via groups.io
> Sent: Saturday, January 18, 2025 1:38:45 PM
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] "Topshim Failed: Signal to noise is too low"
Hi Beth
I would support Feng's suggestion with checking the 2H tuning. Easiest way
is: rpar gradshim1d2h, wobb.
Unfortunately adjusting the 2H tuning is not that easy
You can add an option to topshim to increase the scans. Add the option
"durmax=xx" typically a value of 60 will improve matters.
If that helps you need to change the shim command in ICONNMR to
"topshim durmax=60"
Shimming will take a bit longer but it is more likely to succeed.
Best regards
Clemens
On 1/17/2025 1:16 PM, Beth Moscato via groups.io wrote:
Hi everyone-
We have an AVANCE III (TS 3.7pl5) that’s been sporadically failing
samples saying that the signal to noise is too low. Most of the samples seem
to be marginal quality – usually CDCl3, sometimes with precipitate
or water droplets – but they often manage to successfully shim on
our AV III HD spectrometer, and I’ve noticed a dramatic uptick in
the number of failures recently.
Note that most samples, including most samples in CDCl3, have successfully
run in TS. The TS data I’ve seen from the failed samples show a similar
pattern to those from normal samples (suggesting that the difference is
quantitative and not qualitative).
I’ve done a 3D shim recently, but it hasn’t helped. The lock
phase is set appropriately.
Is there a way to increase the number of scans acquired in TS for specific
solvents? I’m not thrilled with it as a work around, but if it stops
failing the samples, that would be an improvement over the current situation.
Thank you!
Beth Moscato
Temple University
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Received on Mon Jan 20 2025 - 03:18:04 MST