Dear Sameer
4A Sieves may allow the acetone in the Mol sieve channels and the alumina
silicates are can catalyse Aldol reactions. The higher ppm signal could be
from an Aldol product. 3A sieves, presumably are too small for acetone to
enter and the spectrum stay clean. That’s an educated guess, willing
to be shot down in flames.
Rob Lewis
Hull University, East Yorkshire, UK
> From: main_at_ammrl.groups.io On Behalf Of Charles M Garner
> Sent: Friday, July 12, 2024 11:56 PM
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] Sieves for drying NMR solvents?
We have been having problems with our JEOL 400 probe, like lineshape and
sensitivity issues. Its been sent back to JEOL for cleaning like 3 times
in the past 7 or 8 months, with no obvious problems indicated by the
company. There has been some dust in our building from construction and
even concrete work; could that be the problem?
But we are also starting to suspect water in our compressed air. I measured
the compressed air at the instrument as being 16% relative humidity; our
building runs around 55-57 % RH. We have a rather new compressor unit, new
when we acquired our 400, and we have had no issues since installation in
2015. JEOL recommends that we get a Parker UDA-300, cost about $8500.
Any suggestions about dust and drying are appreciated!
Chuck Garner
University of Memphis
> From: main_at_ammrl.groups.io On Behalf Of prashansa agrawal via groups.io
> Sent: Friday, July 12, 2024 2:45 PM
> To: main_at_ammrl.groups.io<mailto:main_at_ammrl.groups.io>
> Subject: Re: [AMMRL] Sieves for drying NMR solvents?
I have been using 3A from sigma Aldrich and it is very clean.
Thanks
Prashansa
On Fri, Jul 12, 2024 at 9:28 AM Sameer Al-Abdul-Wahid via groups.io wrote:
Hi AMMRL,
Does anyone have recommendations for a brand or type of sieves for drying NMR
solvents? One of our users has been using 4A cylindrical sieves, but they are
noticing an impurity in their 1H NMR spectra at around 3.7-3.8 ppm (singlet,
in acetone-d6).
Thanks in advance for your help!
Best regards,
Sameer
--
Sameer Al-Abdul-Wahid, Ph.D. | Manager
Nuclear Magnetic Resonance Centre | University of Guelph
519-824-4120 ext. 58914 | s.wahid_at_uoguelph.ca<mailto:s.wahid_at_uoguelph.ca>
http://nmr.uoguelph.ca/
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Received on Sun Jul 14 2024 - 08:31:56 MST