Hi Paul & "someone"

We run both SO2 and C / N via an Carlo Erba EA and a ThermoFinnigan
DeltaPlus. We have had no problems (ie there is no incresae in backgrounds,
ultimate vacuum, or loss of precision following changing over). For a time
we did run SO2 on our Finnigan MAT 252 together with CO2 and H, and that was
fine in terms of memory & results also. I remember the conventional wisdom
about SO2, but being able to run with the source heated as is possible on
the current generation of mass specs certainly helps. The other major
difference is that most modern analyses use continuous flow through
relatively short sample introduction setups, whereas we used to introduce
SO2 in a via multiport / dual inlet systems with numerous valves,
connections, and bits of stainless steel all under vacuum.

Ian

______________________________________________

Dr Ian Cartwright
Head - School of Geosciences
Hydrogeology and Stable Isotopes
Monash University
Clayton Vic. 3800, Australia
t: 03 9905-4887 / 4879, f: 03 9905-4903

...water, our greatest resource


-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]]On
Behalf Of Paul Brooks
Sent: Friday, 5 May 2006 3:21 AM
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] SO2 and O with same mass spec?


Dear colleagues,

I was just asked by someone who is setting up a lab how feasible it is to
run mostly SO2 analysis on an isotope ratio mass spec, but also some O and
D in water and N and C in organic material from a EA.  I don't do S
analysis, but in the past my understand was that it was desirable to have a
separate mass spectrometer for SO2 analysis if possible.  My understanding
was that SO2 would gradually affect the source and the results for O in
particular but possibly other more stable compounds would deteriorate
compared to a system that does not run SO2.  However, with modern
continuous flow systems perhaps this is not as great an issue.

Any advice on this would be appreciated.

Paul Brooks.