Dear Dave,

Your questions re Zn and its use for water reduction and D/H
analysis prompt me point out that there is a viable alternative.

Mn (manganese) can equally be employed for this purpose and
much more effectively so. This is born out by the not insubstantial
difference in equilibrium constants of the Zn/H2O and Mn/H2O,
which are 1.75x10exp14 and 5.57x10exp24, respectively. Similarly,
the standard potential for the reaction Mn + H2O --> H2 + Mn(OH)2
is +0.732 V, which indicates that the reaction does proceed
spontaneously.

According to Tanweer & Han (IAEA), the optimum reaction
conditions in terms of D/H analysis are 8 microliter of water plus
0.8 g of Mn held at 520 C for 40 minutes.

The "critical" parameter is the particle size of the Mn, which should
be predominantly 100+ micrometer. Such material can be
purchased from FLUKA Chemicals, catalogue #63529, at £11.30
for 250 g. This might not be the actual price though, since my
catalogue is not up-to-date.

Hope this helps.


Best regards,

                          Wolfram



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Dr. W. Meier-Augenstein, CChem MRSC
Senior Research Fellow

University of Dundee, Dept. of Anatomy & Physiology,
OMS, DUNDEE  DD1 4HN, United Kingdom

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Fax  (B): +44-(0)1382-34/5514

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URL: http://www.dundee.ac.uk/anatphys/wma/meieraug.htm
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