The Search for Novel High Molecular Weight Biomarkers (>C40)in Geological Samples of All Ages

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Biomarkers are compounds in geological samples whose basic carbon skeleton resembles that of their precursors which occur in source materials such as algae, bacteria and higher plants. For the most part the biomarkers discovered to date have been in the C10-C40 range. Limitations in both chromatography and mass spectrometry have prevented the successful investigation and identification of biomarkers in the region above C40. It is proposed to take advantage of developments of high temperature capillary columns and tandem mass spectrometers to enter into the frontier area of biomarker geochemistry in the range of C40-C100. Extracts from a variety of well characterized oils and source rocks will be investigated by tandem mass spectrometry in combination with gas chromatography or the direct insertion probe. The samples selected will be those whose lower molecular weight biomarkers have already been extensively characterized. Initially optimum analytical conditions required for the analyses of such novel high molecular weight components will be determined by the use of naturally occurring waxes known to contain long chain n-alkanes. In a parallel approach, attempts will be made to synthesize high molecular weight hopane standards by condensation of hopanoic acids and suitable alkanes or isoprenoids. The resultant products will be characterized by GC- MS/MS and direct insertion probe MS/MS. In addition it is proposed to use tandem mass spectrometry in combination with micropyrolysis techniques to investigate the high molecular weight fragments produced by pyrolytic degradation of kerogens, protokerogens and other insoluble organic materials. The identification of such compounds will expand the utility of biomarkers in many aspects of geochemistry. It should result in a better understanding of paleoclimate and paleoenvironment, biochemical evolution and processes affecting petroleum composition and evolution. With the advances in instrumental technology it is anticipated that there will be an increasing move towards the study of high molecular weight biomarkers. This proposal presents the first formal and systematic search for these compounds.//