ANALYSIS OF KEROGENS AND KEROGEN PRECURSORS BY FLASH PYROLYSIS IN COMBINATION WITH ISOTOPE-RATIO-MONITORING GAS-CHROMATOGRAPHY MASS-SPECTROMETRY (IRM GC MS)

This study describes the application of isotope ratio monitoring gas c hromatography- mass spectrometry (irm-GC-MS) for compound-specific sta ble carbon isotopic analysis of aliphatic hydrocarbon and phenolic pro ducts from flash pyrolysis (800-degrees-C, 20s) of natural biopolymers and sedimentary kerogens. As part of this work, we provide a detailed description of the analysis of complex samples, including approaches for peak integration, data handling and correction for derivative carb ons. Several aliphatic and aromatic biopolymers are analyzed by irm-GC -MS in order to establish relationships between the isotopic signature s of pyrolysis products and those of their parent macromolecules. We a lso analyze a select group of kerogens and kerogen precursors of diffe rent ages and biopolymer compositions to evaluate the applicability of combined pyrolysis/irm-GC-MS to complex geochemical mixtures. Our fin dings suggest that, in spite of the wide degree of heterogeneity, the isotopic values of individual aliphatic and phenolic pyrolysis product s determined by irm-GC-MS can be related to the isotopic composition o f the total organic carbon in kerogens and used to trace its biologica l sources. This study also highlights the need for optimum chromatogra phic separation in order to fully realize the potential of compound sp ecific isotope analyses.