TY - JOUR
T1 - Gas chromatography-pyrolysis-isotope ratio mass spectrometry
T2 - A new method for investigating intramolecular isotopic variation in low molecular weight organic acids
AU - Dias, Robert F.
AU - Freeman, Katherine H.
AU - Franks, Stephen G.
N1 - Funding Information:
We are grateful to Mike Lewan, John Hayes, Stefan Schouten and an anonymous individual for thoughtful, constructive reviews of this manuscript. This work was supported by the ACS Petroleum Research Fund, The Atlantic Richfield Corporation and the United States Geological Survey.
PY - 2002
Y1 - 2002
N2 - A new GC-Pyrolysis-IRMS method was developed for the δ13C determination of carboxyl carbon in low-molecular weight organic acids. By utilizing a palladium-wire reactor at 600 °C with a helium/hydrogen reactant gas, the carboxyl carbon of low-molecular weight organic acids is pyrolytically cleaved and introduced into an IRMS for stable carbon-isotope analysis. The precision of the GC-Py-IRMS method is similar to that of more conventional, combustion-based continuous-flow IRMS techniques and interpretation of isotope-dilution experiments with acetic and octanoic acid shows that the technique is sufficiently accurate for the determination of δ13C values at natural abundance levels. As a demonstration of this new capability, the carboxyl carbon of low-molecular weight (LMW, C2-C6) organic acids generated via hydrous pyrolysis of an oil-prone source rock (the Ghareb Shale) shows δ13C values consistent with the hypothesis that organic acids readily undergo exchange of their carboxyl carbon with aqueous inorganic carbon.
AB - A new GC-Pyrolysis-IRMS method was developed for the δ13C determination of carboxyl carbon in low-molecular weight organic acids. By utilizing a palladium-wire reactor at 600 °C with a helium/hydrogen reactant gas, the carboxyl carbon of low-molecular weight organic acids is pyrolytically cleaved and introduced into an IRMS for stable carbon-isotope analysis. The precision of the GC-Py-IRMS method is similar to that of more conventional, combustion-based continuous-flow IRMS techniques and interpretation of isotope-dilution experiments with acetic and octanoic acid shows that the technique is sufficiently accurate for the determination of δ13C values at natural abundance levels. As a demonstration of this new capability, the carboxyl carbon of low-molecular weight (LMW, C2-C6) organic acids generated via hydrous pyrolysis of an oil-prone source rock (the Ghareb Shale) shows δ13C values consistent with the hypothesis that organic acids readily undergo exchange of their carboxyl carbon with aqueous inorganic carbon.
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U2 - 10.1016/S0146-6380(01)00141-3
DO - 10.1016/S0146-6380(01)00141-3
M3 - Article
AN - SCOPUS:0036190457
VL - 33
SP - 161
EP - 168
JO - Organic Geochemistry
JF - Organic Geochemistry
SN - 0146-6380
IS - 2
ER -