Dear colleagues,
in order to preserve the IAEA standards N1 and N2 we like to have  labstandards with  delta 15 values of 0 ‰ and around 20 ‰. The zero value doesn't appear to be a problem, but a material with the higher value we can't find until now.
Does anyone of you find a readily available material with a d15N of approx 20‰?
Thanks,
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Anita Aerts-Bijma
Centre for Isotope Research, University of Groningen.

Centrum voor IsotopenOnderzoek (CIO), Rijksuniversiteit Groningen
Nijenborgh 4, 9747 AG Groningen, Netherlands
tel +31-50-3634716 fax +31-50-3634738
http://www.rug.nl/cio