Stable Isotope Geochemistry


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[log in to unmask] (Groening Manfred)
Wed, 27 Mar 1996 11:16:46 +0100
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Dear Wolfram, Paul, Natalie,
the paper by Ahmad Tanweer and Liang-Feng Han on " Reduction of microliter 
amounts of water with manganese for D/H isotope ratio measurement by mass 
spectrometry" is published in Isotopes Environ. Health Stud., 1996, Vol.31, 
No experiments were performed on high saline waters.
Most probable a higher amount of Zinc will reduce your problems (until 
absorption of hydrogene gas occurs). See for example "Determination of 
deuterium in brines and in hypersaline aqueous solutions by mass 
spectrometry using zinc as reducing agent" by Ahmad Tanweer, Analyst, July 
1993, Vol.118, pp.835-838  and reference No.5 given in this article.
If really low pH causes this problem, than neutralization using Na2O2 
(sodium peroxide) could be helpful.

Best regards,
                          Ahmad Tanweer, Manfred Groening
                          Isotope Hydrology Laboratory
                          e-mail: [log in to unmask]
From: isogeochem
To: isogeochem
Subject: Re: deuterium in acidic water
Date: Wednesday, 27 March, 1996 09:24

Dear Wolfram,

I have a preprint of a paper by Ahmad Tanweer and Liang-feng Han on
"Reduction of microlitre amounts of water with manganese for D/H isotope
ratio measurement by mass spectrometry". It was submitted to Isotopenpraxis.
I don't know wether or not it was ever published. The results are very
similar to those obtained with Zn reduction with a precision on the order of
+/- 1 per mille. These authors used a 100:1 wt ratio of Mn:water but did
report that there was no amount effect, thus weighing of the Mn was not
critical. They also reported that no reagent pre-treatment was necessary as
you suggested in your note.

Unfortunately the paper does not report on any results from either low pH,
or high salinity waters, so it is difficult to say if it would solve
Natalies problems. I suspect that in this particular case it is the salinity
rather than the pH that is the problem and that using a U furnace would help
matters greatly. Personally I would not want to go down the route of
distillation unless it was a last option.

Perhaps Mannfred Groenning or Kaz Rozanski at the IAEA could comment further
on the Mn method. I think it was developed in the Vienna Lab.


Stable Isotope Laboratory,
Environmental Sciences,