Dear All

1. We are making  N2 analyses from lake waters using a Thermo Finnigan
gas bench connected to Thermo Delta Advantage MS.  The mass 28, 29 and
also 30 nitrogen peaks are nice from the surface waters, but from the
anoxic water taken deeper comes some other tiny peak (seems to be
mass 29 and some 30, but not 28) which is so close after the N2 peak
that it is difficult to separate.  Have you ideas what this peak might
be or have you encountered same problems? 

-The peak may not be CO2 since CO2-derived peak is well separated. If
it is CO I could expect that we could see the peak also in the mass
channel 28. The example chromatograms can be seen here: 

http://users.jyu.fi/~mtiirola/Interfering_peak.jpg   : Only the N2 peak
and the interfering peak after that.
http://users.jyu.fi/~mtiirola/Example_run.cf   : Isodat NT -file: first
5 reference N2-gas peaks and then 10 sample peaks.

2. Is it possible to re-avaluate the existing runs in batch with Isodat
NT 2.0  (+servicepack 3) online or offline.

With Best Regards

Marja

--

Marja Tiirola, Ph.D., Academy Research Fellow
Dept. of Biological and Environmental Science/
Aquatic Sciences
University of Jyväskylä
FINLAND
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