------- Forwarded Message Follows -------
Date sent: Tue, 23 Feb 1999 07:20:33 +0000
From: Herbert.Baumann@eu.apbiotech.com (Herbert Baumann)
Subject: Re: query on HRMAS probe - Thanks
To: "Hongjun Pan | NMR Director" <pan@novell.chem.utk.edu>
Hello there,
I missed your initial query but I'm sending a respons now instead if
you
don't mind. We have a Bruker DRX500 system and received a HR-
MAS probe
about 6 weeks ago. Its a 4 mm z-gradient pfg dual probe with
1H,13C and
2H-lock (standard Bruker probe). The spinning rate is said to be
maximum
15 KHz but it is tested OK for 16KHz. We are running at 5K as
default
since we don't have to bother about the spinning sidebands. For
most
samples that is OK but we have done a studie with a peptide in
liposome
solution and the resolution was drastically increased at 15K compared with
5K. I don't know if you need triple axis gradients but z-gradients do a
lot for inverse experiments. Sample preparation is not too bad it just
takes a few samples to get used to. The rotors from Bruker are open from
the top so you can use ordinary Pasteur pipette for pre-swollen resins and
all other liquid samples and also for quit easy cleaning. We have a sample
changer that can take 30 samples, they are loaded at the top so there is
no need to take out the probe as with Varians variety. We have so far run
9 samples unattended over night without any problems.
In comparision to a microprobe I guess its up to your preferences. If you
only have the option of one probe I would go for the HR-MAS but then you
might be limited in terms of which nuclei you can measure, there is to my
knowledge no broad-band HR-MAS probe available at the moment. Sample
volumes are comparable, the rotors from Bruker have the option to use
either about 80 microliters or 25 microliters with a special insert. For
the 2.5 mm microprobe we have a special spinner that can take capillaries
with OD 1.7, 1.9 or 2.5 mm and use 30, 50 or 120 microliter sample,
respectively. They are easily handled and can be sealed in order to avoid
solvent evaporation.
I'm at the ENC so if you're there you can catch me for a further
discussion.
Good luck
Herbert
*****************************************************************
* Herbert Baumann | herbert.baumann@eu.apbiotech.com *
* Amersham Pharmacia Biotech | phone 070-538 35 72 *
* SE-751 84 Uppsala | fax +46-18-166396 *
* Sweden | *
*****************************************************************
______________________________ Reply Separator
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Subject: query on HRMAS probe - Thanks
Author: "Hongjun Pan | NMR Director" <pan@novell.chem.utk.edu>
at Internet-APBiotech-Europe
Date: 1999-02-22 13:27
Dear Friends:
Regarding my query on HRMAS probe, there are only two
responses so far, but there are six people requested to post the
summary to the net. It seems that this probe is still not popular
and more people are interested in this probe. I just post the two
responses here for your information.
Thanks to all who responsed my query.
H. Pan, Ph. D. | Director of NMR Lab
Department of Chemistry
University of Tennessee
Ph: 423-974-3386
Fax: 423-974-3454