A good trick to learn from the biologists: if it is too much salt you can often
get tuning and matching to work with a smaller diameter tube we often go from
5mm-3mm. Obviously s:n will be down unless you use a more concentrated sample.
This will often return your pulse widths to something normal as well and
decoupling will again work as expected
Regards
Gary
> From: main_at_ammrl.groups.io on behalf of Vander Velde, David via groups.io
> Date: Tuesday, 24 June 2025 at 18:14
> To: main_at_ammrl.groups.io <main_at_ammrl.groups.io>
> Subject: Re: [AMMRL] New Error on Varian 400MR
Yes, assuming that's the 1H match control on your system (it's channel 6 on
mine). High ionic strength samples drive the match towards its minimum value,
and once you reach that in a particular probe, you're out of luck with getting
the sample properly matched.
Setting aside the question of whether it's necessary or advisable to prepare a
sample like that, you can still get some kind of 1H spectrum by skipping probe
tuning, taking some big hit on sensitivity. Some experiments are not going to
work or not advisable, like 13C with 1H decoupling—you'd get high reflected
power back from a mismatched probe, and the normal decouplingparameters will fail.
________________________________
> From: main_at_ammrl.groups.io on behalf of Stephen Nolte via groups.io
> Sent: Tuesday, June 24, 2025 8:13 AM
> To: main <main_at_ammrl.groups.io>
> Subject: [AMMRL] New Error on Varian 400MR
Hi all,
Summer research students elicited a new intermittent error this week on our
Varian 400MR failed - rf signal too weak on tune chan#5.
Can this be related to high levels of ionic salts in the sample?
Thanks!
_______________________________
Stephen Nolte | Chemistry Technician
Millersville University
717-871-7413
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Received on Tue Jun 24 2025 - 13:33:03 MST