Dear Anders, Bob and Peter,

we are working on delta 13 C from CH4 emitted by peatlands and are willing
to join the measurements as well.

We have a Finnigan PreCon/Gasbench combination and measure from 1.7 ppm  up
to 50 ppm CH4 in 100 ml flasks with an autosampler.
We will try to measure higher CH4 conc. as well by manually injecting the CH4.

We also have the problem of finding a good standard. Now we have a 50 ppm
CH4 mixture in synthetic air which we use as reference during our
measurements, but we don't know the value of this CH4.
This gas is analysed now with GC combustion CF-IRMS in another lab, this
system is calibrated versus NGS 1 .

For our 50 ppm reference we have good stdev but the absolute value still
wanders too much in time.

I can also try to inject small amounts of 1% or maybe even pure CH4 in the
100 ml flasks and measure it that way.

I can also send my 50 ppm CH4 to you if you like.


Best regards,


Richard van Logtestijn







@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Richard van Logtestijn
Vrije Universiteit
Faculty Biology
Department of Systems Ecology
De Boelelaan 1087
1081 HV Amsterdam
the Netherlands
tel +31 20 4447247
fax +31 20 4447123
e-mail : [log in to unmask]
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@