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Subject: GC/MS


From: Jens Glastrup <jens.glastrup>
Date: Tuesday, April 17, 2001
Tatiana Falcon <tatia12 [at] hotmail__com> writes

>I would appreciate any comments on the sensibility, characteristics,
>and quality of the GC/MS Qp-5050 Shimadzu offers since I'm about to
>apply for a Japanese funding and need to invest the grant in
>Japanese equipment. It would also be very useful to have the names
>of other brands that might be better.

As you are about to raise Japanese money and if you are considering
a bench top GC/MS, I do not think that there are many other
possibilities than Shimadsu, and I personally also think that this
should be all right. It does not have the lowest sensitivity on the
market, but that does not have any meaning to you no matter what you
analyse in the museum field. However, as I guess that this is your
first mass spectrometer, you should consider some aspects before

As I guess that your budget is limited (after buying), I find it
utterly important that you contact other users in Mexico, to ensure
that the running costs are not too frightening, especially the turbo
pump is probably expected to last two/three years, and the price of
a refurbished/new turbo should not be neglected. Other expensive
spare parts are the filament and the detector of the MS, what is the
expected average life of these parts? Are there other parts which do
often break down, any pre-filter before the quad? Other questions?

Furthermore you should examine the customers day-to-day satisfaction
with the instrument, is it a work horse, or are there elementary
problems which require the assistance of a service technician on a
regular basis? In Denmark one service hour is at least 150$ and we
do have a sad example on a laboratory which had to close down their
GC/MS service because of constant problems with their GC/MS. If you
have disappointing answers to these questions, then find another MS!
Nothing is worse than having an MS which you cannot afford to run.

Daily work: What are you considering to analyse on the GC/MS?
Anyway, in my opinion an On Column injector is a must as it allows
you to inject small samples without discrimination. Split/splitless
is tempting, however you will probably see some discrimination in the
high molecular end (triterpenes/wax components), even though the
salesman would try to convince you that this is not a problem with
their injector. For the optimum versatility of your equipment you
should however have both types of injectors mounted on your GC, it
is a cheap investment now, but it could be difficult/expensive to
have it retrofitted later.

Jens Glastrup
Senior Research Scientist
The National Museum of Denmark
Department of Conservation

                  Conservation DistList Instance 14:55
                 Distributed: Thursday, April 19, 2001
                       Message Id: cdl-14-55-005
Received on Tuesday, 17 April, 2001

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