Dear Bill and Pier,
'Probably a matter Willi can give us some more expertise..'
I guess I have to. I take the blame. Enriched studies never were the
focus when developing mass spectrometers and the machines in Bremen
never see any enriched stuff. (In fact, a lot of the enriched stuff can
probably be done more conveniently with ordinary organic mass
spectrometers that cover a wide dynamic range on a single SEM
collector). Thus, errors in the calculations of enriched material may
have slipped through and may still be present in versions of Isodat in
use.
I can only recommend to ALWAYS be critical about results from third
party software. The scientist that publishes data is responsible for
them, no one else.
In the case of at% calculation I would use the reported delta values and
plug them into a spreadsheet for further calculation and referencing.
This is what we do with all data in order to connect samples and
references together. The mass spec in principle 'knows' only the actual
sample and does not interconnect results from different runs.

Regards from Jena    Willi

Pier: when is your book coming out? I guess a large number of the
questions discussed on Isogeochem could be answered if it were out
already.

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Willi A. Brand, Stable Isotope Laboratory       [log in to unmask]
Max-Planck-Institute for Biogeochemistry
Carl-Zeiss-Promenade 10, 07745 Jena, Germany    Tel   +49-3641-643718
P.O.Box 100164, 07701 Jena, Germany             Fax:  +49-3641-643710
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