Dear Lars,


> Plan to buy a GCMS in addition to my GC-C-IRMS. What are the important
> parameters to look for?

What kind of applications do you anticipate?

> Ion Trap vs Quadropole vs Magnets?
> MS vs MSMS?
> EI vs CI?

I rather like Ion Trap mass specs since they give you MS, MS/MS,
EI and CI capabilities in one instrument. I think Finnigan's latest
offering is called PolarisQ. I don't know that instrument first hand
but I was quite happy with its predecessors, the Magnum (no, not
Wall's favourite ice-cream) and the more recent GCQ.

In principle, an Ion Trap is nothing but an intelligent and more
sensitive Quadrupole.

> I am used to the HP5972 MSD EI. Will it do the job?

HP's MSD is a nice bench-top machine that's easy to use and very
abundant, so there is a huge user info base. My personal bone of
contention with the MSD is its source - quadrupole - analyser /
vacuum layout that drags all the rubbish over the quadrupole.

> Will be used when GCCIRMS is not needed, for low concentrations when GCCIRMS
> can not be used and for MIDA as well as for standard GCMS analysis of
> endogenous componds.

If you want to do stable isotope work with enriched samples than
the Ion Trap is definitely the machine to go for while keeping
equipment cost at a reasonable level.

Try to get in touch with these guys:

van Eijk HM, Rooyakkers DR, Soeters PB, Deutz NE

Department of Surgery, Maastricht University, Maastricht, NL-6200
MD, The Netherlands.

They used an LCQ for the analysis of enriched amino acids with
samples sizes in the range of 250 to 400 pmol.
The LCQ is an Ion Trap mass spec interfaced to HPLC.

Even so you want to do GC-MS, I would have thought you could
use their Ion Trap settings as a starting point for your work, at least.


Best regards,

                      Wolfram




Dr. W. Meier-Augenstein, CChem MRSC
Senior Research Fellow

University of Dundee, Dept. of Anatomy & Physiology,
OMS, Small's Wynd, DUNDEE  DD1 4HN, United Kingdom

Tel.: +44-(0)1382-34/5124, /4574, /4968
Fax:  +44-(0)1382-34/5514

e-mail: [log in to unmask] (work)
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URL: http://www.dundee.ac.uk/anatphys/wma/meieraug.htm


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