Hi everyone :-)

Michael Cheatham wrote the following about Advice on New MS purchase:

> Dear Readers,
>
>         The Geology Department here at Syracuse University is preparing to
> place a purchase order for a new Stable Isotope Ratio Mass Spectrometer
> for analysis of H/D, 13C, 15N, 18O, and (maybe) 34S.  I have been
> directed by our Department Chair to make serious inquiries about the
> true performance characteristics of the various mass spectrometers
> currently being offered by Finnigan, Micromass, and Europa.

A bit of background:  I work in the Isotope Geology Unit of the SURRC
in East Kilbride, and we have 2xVG602s, a VG SIRA 9, a VG SIRA 10, a
VG SIRA II, a VG Isochrom, a VG Optima, a VG PRISM II, a VG PRISM III,
a Finnigan 251, a Finnigan Tracermat, an Analytical Precision 2003,
and a Europa ANCA-NT/20-20.  Any machines I've missed, I apologise to
in advance ;)

I spend most of my life (working and otherwise), looking after these
babies, so would like to chuck my experience, and (relevant?)
experiences onto the heap.

>         We will be purchasing a basic mass spectrometer, an automated
> carbonate preparation device, an automated water equilibration device,
> and a continuous flow interface.  The analysis of extremely small
> carbonate samples will comprise a significant percentage of our
> analyses.  We are particularly interested in obtaining feedback from
> <bold>you,</bold> the users, of these instruments regarding the
> performance in terms of accuracy and precision for extremely small
> samples.  We would also like to know just how small a sample weight can
> be analyzed and stay within the accuracy and precision envelope.  How
> many of you are running samples in the 20 ug, 10 ug, or smaller range?
>  Likewise we would like to know how successful your laboratory has been
> with automated water equilibration devices.

Our PRISM II has the VG Isocarb device fitted, which allows automatic
unattended running of up to 44 carbonate samples in a batch.  I have
also had experience of Edinburgh's PRISM III with the same prep
system, and the Isocarb really does get a chance to make use of the
extreme stability and sensitivity of this machine.

From memory, VG are quoting a mimimum sample size of 25µg on the PRISM
III, but Edinburgh's machine has gone down to the 10µg range (below
the range of their balance!), and still produces perfect, meaningful
analyses.  Most of the problems they've had have been software rather
than hardware, but VG (their new name eludes me.  Iso#?) have gone a
long way to getting their latest software bug free, and most of the
bugs in the version I saw were "irritating" rather than damaging.  I
haven't heard any complaints from them of late, so things must be
better under the latest version :)

Our own PRISM III is just over 4 years old (VG's prototype machine),
and has had very few problems outside "normal" things, such as
filament changes, source cleanups etc.  We have had problems with
turbo controllers, but our machine, being the prototype, has a totally
different controller setup to the production machines, which seem to
be much, much less prone to blowing controllers.  The mass spec itself
(ie the sofware, I suppose)  is really easy to use, and as I said, the
software is continual development, so

Apart from its main use, which is running CO2 samples from a LASER O2
system, we also have an Analytical Precision water equilibration
system connected to the PRISM.  This is a modification of their breath
analyser, and simply connects to the continuous flow port of a PRISM
or Optima.  This makes switching from normal dual inlet mode to
continuous flow mode a matter of simply opening or closing the PRISM's
continuous flow valve, and loading the continuous flow software.
Takes all of about 1 minute each way.  The water equilibration system
supplies its own reference gas from a small cylinder, and of course
the helium carrier.  The samples are dried using a rather clever
Nafion trap, so there are no cryogenics involved, and reaction vessels
are extremely cheap, and disposable, so no cleaning up afterwards
<sigh>  The method of analysing the gas from the vessels only uses
about 5% of the gas, so multiple analyses per tube are possible.  It
performs well within the quoted spec of ±0.3 per mille.  We have had
no major problems with the system in a year of continuous use, and its
simple design means there is basically no routine maintenance.  Highly
recommended.  In fact, although we originally bought the water prep as
an add-on for the PRISM III, we now have a dedicated Analytical
Precision 2003 mass spectrometer to cope with the huge number of
different things we now do with this prep system.  Because this is
"only" a continuous flow mass spec, it is extremely simple in design,
cheap to buy, and cheap to maintain, and rivals the PRISM in terms of
linearity (But, not sensitivity.  For water samples this is /never/ a
problem!).

>         I am also interested to hear about your experiences with the
> representatives of the three companies: sales staff, service staff,
> spare parts department, etc.  How were you treated during the warranty
> period?  How were you treated after the warranty expired?  Have you had
> bad experiences in obtaining spare parts for the instrument?  Have you
> ever had the need to acquire a part that was not available on the open
> market.  Did the MS manufacturer charge a reasonable price for the
> part, or did you feel taken advantage off?  I have been through the
> process of purchasing mass spectrometers a couple of times in the past,
> so I already know what the spectrum of answers will be for the
> questions in this paragraph, yet I'd still like to hear your
> experiences.

I've dealt directly with VG, Analytical Precision, and Finnigan
engineers and sales staff over the years (not Europa.  Yet?).

VG seem to be getting back into the swing of things after a rocky few
years under Fisons.  I have never had a problem getting advice,
obtaining parts and they have always been very courteous.  Their
system of logging fault calls, and replying to them later to check if
your problem has been resolved is really nice!!  It makes you feel
less "forgotten about", when you're up to your elbows in electronic
components, with 20 circuit diagrams scattered on your bench, if
someone phones and says "Anything I can do to help?" <sigh again>
They were very supportive during the warranty periods of all our
machines, quite happy to send engineers out for major problems and
send spare parts to identify and correct faults.

Analytical Precision is formed mostly of ex-VG people, who left around
the time that Fisons were at the very peak of their mismanagement.
Although they're a young company, they seem to have drawn on the good
points of the "old" VG, and provide very good customer service.
They also supply spares for just about every machine we use, and even
fairly obscure things (this week, a TracerMAT filament), can be
obtained within less than a week.  We've had very few problems with
both the water prep and the mass spec, so it's hard to say just how
good their aftersales service is, but the minor problems we have had
have been dealt with very promptly and courteously.

The 251, which we bought 2nd hand, and thus out of warranty, has been
nothing short of brilliant for a 10-year old machine, and because of
this, our contact with Finnigan has been very small.  The only things
I've had to contact them for have been a leaky reference bellows, a
filament, and a blown 3-phase transformer.  The biggest "problems" are
that (1) parts are stocked in Germany, so everything takes about a
week to arrive, and (2) the cost of spares overall is very high.
Their customer service is excellent, though.  Very friendly and
competent people.

There we go.  A bit disjointed, I know, but it's all in there
somewhere ;)

Totty  <8^)