Dear subscribers
an additional comment to the H2 working standard problem.
Gerhard Strauch

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>From: [log in to unmask] (Gerhard Strauch)
>Subject: H/D working standard
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>Hallo Nori,
>concerning the H/D preparation methods we would like to point you out to
the water reduction with chromium metal at high temperature. Water (minimum
3 micro-l) is reduced at a 850 degree Celsius Cr-contact by evaporating and
passing the Cr under vaccum. We have an off line preparation technique using
a toeppler pump to carry the hydrogen to ampoulles. Former use of ampoulles
filled with Cr + sample and breaking after reaction was not very successful
because of adsorped hydrogen in the Cr which made worse the precision.
>The standard deviation is better 1 per mil. All kinds of water can be used
for routine H/D analyses with Cr reduction: groundwater, sea water, water
with organic compounds ...
>At the last IAEA-Advisory Group Meeting (Dec 11-14, 1995, in Vienna) we
gave a brief report about the chromium reduction technique. Our experiences
and some results will be published next time.
>In this year, the Finnigan Mat Ltd. Bremen will offer a on-line preparation
device for hydrogen at the IRMS delta s using the chromium reduction technique. 
>
>Regards
>Gerhard
>
>Gerhard Strauch (or) Peter Kowski (or) Matthias Gehre
>Center of Environmental Research Leipzig-Halle Ltd.
>Section of Hydrogeology
>Hallesche Strasse 44
>D-06246 Bad Lauchstaedt
>Tel: ++/49/34635/73218
>Fax: ++/49/34635/73287
>e-mail: [log in to unmask]
>        peter [log in to unmask]
>        [log in to unmask]
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Str