Isotope Geochemists,

I am wondering what other labs are using for pyrolysis O-18 standards.  We
have had pretty good luck with NBS127 (BaSO4), NBS 120C (Florida Phosophate
rock prepared as AgPO4) and NIST 8542 ANU Sucrose. This gives a range of
+9.3 to +36.4 O-18.  We tried to add a cellulose standard which should be
around +20, and used an Aldrich cellulose microcrystalline powder
(43,523-6).  This cellulose has about 0.5 per mil O-18 variability.  Can
anyone suggest a cellulose standard that might have less O-18 variability?

Thanks,

Bill
William J. Showers
Dept of Marine, Earth & Atm Sciences
North Carolina State University
Raleigh NC 27695

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