Dear All,

Some years ago we bought a flow-through reactor for water D/H analysis.
The producer sold it with zinc. However, zinc evaporation caused an
incredibly bad reproducibility. See

Demény, A., Fórizs, I.(1991): On some preparation methods in stable
isotope mass spectrometry and their geochemical applications. Rapid
Communications in Mass Spectrometry, 11, 524-526.
Demény, A. (1995): H isotope fractionation due to hydrogen-zinc
reactions and its implications on D/H analysis of water samples.
Chemical Geology, 121, 19-25.

In order to prove that indeed the zinc is guilty, I put chromium (Riedel
de Haen, "pulver") into the reactor. The results were very nice, I
obtained -428 for SLAP, whereas we use a normalization factor of 1.05
with zinc. However, after about 20 conversions, the "entrance" Cr
surface was oxidized and blocked the way. My questions are:
- is the zero SLAP/SMOW normalization correction general with Cr?
- Gerhard, Rolf, do you shake periodically the reaction chamber to renew
the Cr surface?

Cheers,
Attila



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Dr. Attila Demeny
Laboratory for Geochemical Research
Hungarian Academy for Sciences
Budapest, Budaorsi ut 45,
H-1112 Hungary
Tel/fax: 361-319-3145
e-mail: [log in to unmask]