The classical extraction scheme including as the final step the Cr
reduction seems to work well. We have applied it succesfully to
organic-rich but also -poor marine sediments from the Mediterranean to
look for 34S/32S ratios in organic matter and co-existing pyrite.
We observed no cross-contamination with pyrite even in samples with
very low (organic) sulfur contents.

Cheers
Michael

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Dr. Michael E. Boettcher
Department of Biogeochemistry
Max-Planck-Institute for Marine Microbiology
Celsiusstr.1
D-28359 Bremen
Germany
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