Dear Attila,

May I draw your attention to the following part of my message to 
Colin? This should answer your question about the amount.

> According to 
> Tanweer, the "optimal" conditions are to use 0.8 g of Mn for 8 ul of 
> water at 520 C for 40 min. Particle size should be between 50 to 100 
> um.

Within the SD of 0.6 0/00 there is no siginifcant difference between 
delta D values obtained after reaction identical amounts of water 
(0.8 ul) with different amounts of Mn (0.6 to 1.0 g). I had no 
difficulties reproducing Tanweer's results for VSMOW samples. Tanweer 
measured VSMOW, GIST and Vienna tab water with consistent results for 
all three.

I didn't investigate what the precise compostion of my spent Mn was, 
but it would appear to be almost exclusively MnO. 

Routinely, our lab uses a reltively new method to measure H/D. We 
react our samples with CaC2 to yield acetylen and then measuring 
27/26 ratios. My colleague Ayyub Patel will be able to give you more 
detailed information on this procedure ([log in to unmask]).

If you wish I will send you a photocopy of the Mn paper.


All the best,

                    Wolfram

*****************************
Dr. W. Meier-Augenstein
Hon. Lecturer in Chemistry

University of Dundee
Dept. of Anatomy & Physiology
Small's Wynd
DUNDEE  DD1 4HN
United Kingdom

Tel.: +44-(0)1382-34/5124, /4968
       +44-(0)468 -314563
Fax:  +44-(0)1382-34/5514

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URL: http://www.dundee.ac.uk/AnatPhys/wolfram.htm