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Thu, 27 Jul 2000 15:14:39 +0200 |
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At 00:02 27/07/00 -0400, you wrote:
>> does anyone know a supplier for CH4 gas with a certified delta 13C
>> value at natural abundance (around -45 permil) and/or enriched with a
>> few hundred permil? I tried Messer Griesheim, but they don't have it.
>> Are there more people working on determining delta 13C from CH4,
>> either from emissions or air? It would be interesting to share some
>> experiences.
Dear Richard,
We are working here on d13CH4 measurements in the atmosphere and polar ice
cores, using CF-irMS. For the standard, we work with a tank of pure CO2
prepared by Air Liquide in France. Their source of CO2 has a signature
quite close to the atmospheric signature of methane (our tank is at -46
permil). The CH4 standard allowing to test the full analytical procedure is
actually made of several tanks of atmospheric air which has been calibrated
by other laboratories using off-line combustion. So we have inside each
tank CH4 at about 1700ppbv in air, with a signature around -47.1 permil. I
don't know of a supplier of pure CH4 with certified delta13C, apart from
Cambridge Isotope Laboratories which supplies small amounts, I think.
Keep in touch. Best regards,
- Jérôme.
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Jerome Chappellaz
CNRS Laboratoire de Glaciologie et Geophysique de l'Environnement
54 rue Moliere - Domaine Universitaire
BP 96
38402 Saint Martin d'Heres Cedex FRANCE
Telephone: +33 4 76 82 42 64
Facsimile: +33 4 76 82 42 01
E-mail: [log in to unmask]
Internet: http://glaciog.ujf-grenoble.fr
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