Dear all,

we have been using Labco Exetainers for storing soil gas samples and 
subsequent N2O or CO2 analysis by GC or IRMS for many years. This has 
been very useful because they proved to be more tight than other vials. 
Recently we tried the vials for CH4 analysis of soil gases. 
Unfortunately we found that CH4 standard gases stored in the Exetainers 
exhibited elevated CH4 signals. We attribute this to CH4 bleeding from 
the septa. Heating the septa to 80°C under Vacuum did not solve the 
problem.

My questions:

Has anyone observed this before? Or is someone using Exetainers 
successfully for CH4 work? Any idea on alternative septa which are as 
good in tightness as the original Labco septa?

Thank you,

Reinhard

-- 
____________________________________________________________
PD Dr. Reinhard Well
Telefon: +49 (0)531 596 2535
Fax: +49 (0)531 596 2599 
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Adresse:
Johann Heinrich von Thünen-Institut
Bundesforschungsinstitut für Ländliche Räume, Wald und Fischerei
Institut für Agrarrelevante Klimaforschung 
Bundesallee 50 
38116 Braunschweig 
Deutschland 
Web: http://www.vti.bund.de/de/institute/ak/

address:
Johann Heinrich von Thünen-Institut
Federal Research Institute for Rural Areas, Forestry and Fisheries
Institute of Agricultural Climate Research 
Bundesallee 50 
38116 Braunschweig 
Germany 
Web: http://www.vti.bund.de/en/institutes/ak/