Re: [AMMRL] 99.8% MeOD vs 80% Ethylene Glycol

From: Clemens Anklin via groups.io <clemens.anklin=bruker.com_at_groups.io>
Date: Tue, 22 Aug 2023 18:46:07 +0000

Hi Weixing

another option is to use a pulse just a fraction lager than a 360. The small
sharp positive peaks that raise above the baseline are at the true resonance
position.

Regards

Clemens


On 8/22/2023 2:07 PM, Donghui Wu via groups.io wrote:

Hello Weixing,

If radiation damping is the problem, you might be able to get a spectrum without
its effect by using the shortest pulse width with lowest level of RF power
possible, i.e. a very very small flip angle. This will let you use the calibration
sample you already have (80% ethylene glycol) and the well established NMR
temperature measurement parameters.

Regards,
Donghui


On Tue, Aug 22, 2023 at 1:03 PM Zhang, Weixing via groups.io <Weixing.Zhang=stjude.org_at_groups.io wrote:
Dear All,

Thanks to everyone who has read and replied to my email.
We want to use a CryoProbe to run experiments at different temperatures up
to 90 oC (363 K).
Many people think that radiation damping of 80% ethylene glycol is the problem.
Massively detuning the cryoprobe or using deuterated ethylene glycol should
give more accurate results.

Clemens told me that the Bruker part number of 99% ethylene glycol-d6 is Z10629.
Z10629 is currently under development in Germany and it would be about a month
for it to be completed.

The Bruker AU program calctemp has these options.
[cid:part1.44IXH932.2knSg0nY_at_bruker.com]
[cid:part2.1qCo1HAF.8C5Tggu5_at_bruker.com]

I am curious where Bruker got the equations from, and I would greatly appreciate
any information.

With warm regards,

Weixing Zhang (Walter)
Research Operation Manager
Biomolecular NMR Spectroscopy Center
St. Jude Children’s Research Hospital
Memphis, TN 38105
USA


> From: main_at_ammrl.groups.io<mailto:main_at_ammrl.groups.io> <main_at_ammrl.groups.io> On Behalf Of Clemens Anklin via groups.io
> Sent: Friday, August 18, 2023 2:26 PM
> To: main_at_ammrl.groups.io<mailto:main_at_ammrl.groups.io>
> Subject: Re: [AMMRL] 99.8% MeOD vs 80% Ethylene Glycol

Hi Weixing

if you do this on a cryoprobe this will be the expected result. 80% Glycol
gives a massive amount of radiation damping. This leads to different readings
as shown by Stefan Berger in https://doi.org/10.1002/mrc.1941

You can try to run a more accurate measurement by massively detuning the probe.

With best regards

Clemens
On 8/18/2023 3:09 PM, Walter Zhang wrote:


Dear All,
I need to use 80% Ethylene Glycol for high temperature calibration. [cid:part3.AcSZ79NJ.WV0uadNH_at_bruker.com]

Before I do the calibration, I compared it with 99.8% MeOD at 303 K.

When I set temperature to 303 K,
99.8% MeOD gives 303.03 K while 80% Ethylene Glycol gives 300.57 K

The difference between the two calibration samples is 2.46 K.
Is this normal?
Your comments are appreciated!

Best regards,
Weixing Zhang
St. Jude Children’s Research Hospital
Memphis, TN 38105
USA


________________________________



--
==========================
==========================
====================
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 Aug 22 2023 - 11:58:53 MST