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 If you analyze only carbon isotope, even 24 hour reaction time would be 
OK at 70 C, only the oxygen isotope is altered.  Please read the paper:

Rvsz, K.M., and Landwehr, J.M., 2002, 13C and 18O isotopic composition 
of CaCO3 measured by continuous flow isotope ratio mass spectrometry: 
Statistical evaluation and verification by application to Devils Hole core 
DH-11 calcite: Rapid Communications in Mass Spectrometry, v. 16, p. 
2,102-2,114. 

Kinga Revesz
Research Chemist, Stable Isotope Laboratory
U.S.Geological Survey
MS 431
Reston, VA 20192
T:703-648-5865
FAX: 703-648-5274

http://www.isotopes.usgs.gov



From:
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To:
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Date:
05/07/2011 07:59 PM
Subject:
carbonate reaction temprature for GasBench
Sent by:
Stable Isotope Geochemistry <[log in to unmask]>





Most labs react carbonates (calcite) with phosphoric acid at 25 C for 24 
hours to run them on the GasBench.

If I remember correct while running Kiel Carbonate device the temperature 
for reaction was 70 C and the reaction time was around 40 (?) minutes. Is 
there any reason that will affect the isotope values if I react calcite 
for GasBench for an hour at 70 C and running them right away?

Thanks

Million