EVIDENCE FOR PORPHYRINS BOUND, VIA ESTER BONDS, TO THE MESSEL OIL-SHALE KEROGEN BY SELECTIVE CHEMICAL DEGRADATION EXPERIMENTS

High amounts of nickel mono-and di acid porphyrins were released from Messel oil shale kerogen (Eocene, Germany) by selective chemical degra dation (acid and base hydrolysis). The released porphyrin fractions we re quantified (UV-vis) and their constituents isolated and characteriz ed at the molecular level (UV-vis, MS, NMR). The mono-acid porphyrin f raction released contained four compounds of similar abundance which a rise from an obvious chlorophyll or bacteriochlorophyll precursor. The di-acid porphyrin fraction was, however, dominated by far by one comp ound, mesoporphyrin IX, which must have originated from heme-like prec ursors (heme, cytochromes, etc.). These results show unambigously that the released mono-and di-acid porphyrins were linked to the macromole cular kerogen network via ester bonds and suggest that precursor heme- like pigments could he selectively and/or more readily incorporated in to the macromolecular kerogen network than precursor chlorophylls and bacteriochlorophylls. Copyright (C) 1997 Elsevier Science Ltd.