Dear All,

We were planning to run some cellulose-d18O analyses in our lab, and 
I had a question about d18O standards.  A number of papers that have 
run similar analyses state that they calibrate a working cellulose 
standard (e.g. from Aldrich or Sigma) for d18O and use this when 
running samples, but the papers don't say what standard they use to 
calibrate this working standard.

Cellulose standard IAEA-CH-3 is available from IAEA, but is certified 
for d13C only, not d18O.  Is there a consensus d18O value that people 
use for this standard?  Or do people use other certified standards, 
such as benzoic acid IAEA-601 (+23.3 per mil), or barium sulfate 
NBS-127? (+9.3 per mil)

Thanks in advance for any comments and suggestions.

Cheers,
Simon Poulson


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Simon Poulson
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