on 05-11-201704:42 AM - edited on 11-09-202104:00 AM by usermigration2
Max Planck Institute for Biogeochemistry, P.O. Box 100164, 07701 Jena, Germany Rapid Communications in Mass Spectrometry (2005), V19, pp1097–1119, doi: 10.1002/rcm.1886 Calcite-CO2 mixed into CO2-free air: a new CO2-in-air stable isotope reference material for the VPDB scale Prosenjit Ghosh, Michael Patecki, Michael Rothe and Willi A. Brand In order to generate a reliable and long-lasting stable isotope ratio standard for CO2 in samples of clean air, CO2 is liberated from well-characterized carbonate material and mixed with CO2-free air. For this purpose a dedicated acid reaction and air mixing system (ARAMIS) was designed. In the system, CO2 is generated by a conventional acid digestion of powdered carbonate. Evolved CO2 gas is mixed and equilibrated with a prefabricated gas comprised of N2, O2, Ar, and N2O at close to ambient air concentrations. Distribution into glass flasks is made stepwise in a highly controlled fashion. The isotopic composition, established on automated extraction/measurement systems, varied within very small margins of error appropriate for high-precision air-CO2 work (about 0.015 permil for d13C and 0.025 permil for d18O).