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Dear Frank
The quick way to establish if the column is a problem is to set up a rough
and ready injection system immediately prior to the column. A 1/4" tee with
1/4 by 1/16 PTFE ferrules will connect to your 2mm EA tubing and a GC septa
will do as the injection port. Inject some CO2 and if the spreading does not
occur then the column, transfer line and mass spec are OK.
regards
John

> -----Original Message-----
> From: Frank Pawellek [SMTP:[log in to unmask]]
> Sent: Friday, February 18, 2000 11:24 AM
> To:   [log in to unmask]
> Subject:      tailing of CO2 peak in EA-MS
>
> Hi all,
>
> I would appreciate if somebody could point to me to the solution of
> the following problem: I am running a EA-MS  (Carlo Erba
> CHN 1110 + Delta C) for analysis of 13 C and 15 N in a variety of
> materials.
>
> After switching the instrumen off and back on about two weeks ago,
> the CO2  showed a broad tailing, resulting in wrong results
> for 13C/12 C in standards and also too low measured C -
> concentrations. The N2 peak seems perfectly o.k., concentrations and
> isotope ratios. I have changed the O2 and carrier flow rates in all
> directions, put on new oxidation and reduction columns, renewed  the
> Anhydron water trap - but, alas, to no avail...
>
> Is it possible the chromatographic column needs to be changed (the
> instrument has done about 10000 measurements).
>
> Any help VERY welcome !
>
> Frank Pawellek
>
>
> +++++++++++++++++++++++++++++++++++++++++++++++
> Frank Pawellek
> Institut fuer Geologie
> Lehrstuhl fuer Sediment- und Isotopengeologie
> Ruhr-Universitaet Bochum
> Universitaetsstrasse 150
> 44801 Bochum
> Germany
> Phone: +49-234-700-5458
> Fax: +49-234-7094-571
> +++++++++++++++++++++++++++++++++++++++++++++++