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A number of structural isomers of C 33 2,5-dialkylthiophenes (I), C 33 , C 37 , C 38 2,6-dialkylthianes (II), and 2,5-dialkylthiolanes (III) have been identified in sediment extracts from the Nordlinger Ries, southern Germany. The identifications are based on gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) analysis and confirmed by carbon skeleton determination on desulfurization products using Raney nickel treatment. All the organic sulfur compound classes mentioned exhibit structural distributions dominated by a limited number of all theoretically possible isomers. This provides further evidence for the formation of these compounds by abiogenic incorporation of sulfur into functionalized lipids at the early stages of diagenesis

Three main series of bound steroidal acids have been tentatively identified, in low concentrations, in the hydrolysates of kerogens and the extractable polar fractions of sediments from the Nordlinger Ries (southern Germany), and in a kerogen sample from the Monterey Formation (California). The results provide further evidence of the widespread occurrence of 3-carboxysteroids and indicate that they are chemically bonded to the complex network of kerogen through ester linkages. This suggests that these compounds could represent a yet unrecognized family of compounds occurring in the biosphere

Free fatty and hopanoic acids, and hydrocarbons of five organic- and sulfur-rich lacustrine sediments from Nordlinger Ries black shales (southern Germany), have been studied by gas chomatography and computerized GC-MS. The results indicate that Nordlinger Ries sediments contain abnormally high concentrations of those free acids (up to 57% of total extractable bitumen). Besides n-alkanoic, monomethyl, and isoprenoid acids common to any other immature sediments, high concentrations of C 16 and C 18 10-oxoalkanoic acids are unusual constituents of these sediments. The high concentrations of fatty acids in the bitumens are attributed to early diagenesis. The carbon distributions of the acids are consistent with an origin mainly from planktonic and microbial organisms

In order to obtain more information on the structural entities bonded to the macromolecular structure of Monterey kerogen, the solvent-extractable acidic products obtained by mild alkaline hydrolysis were investigated by gas chromatography and combined gas chromatography-mass spectrometry analysis. On the basis of the results obtained, the previously proposed structural feature of Monterey kerogen is expanded to include saturated normal monocarboxylic acids (C 8 -C 36 ), saturated normal α,ω-dicarboxylic acids (C 7 -C 29 ), isoprenoid acids (C 14 -C 17 , C 19 -C 21 ), iso and anteiso acids (C 11 -C 18 ), unsaturated acids (C 16:1 , C 18:1 ), aromatic acids, hopanoid acids, and 3-carboxycholestane, as well as a complex mixture of alkylated thiophene carboxylic acids (C 6 -C 11 )

Computerized capillary gas chromatography-mass spectrometry (GC-MS) was employed to investigate maleimides (1H-pyrrole-2,5-diones) produced from a controlled stepwise oxidation of bitumen-free kerogen samples isolated from Green River and Monterey oil shales. On the basis of the evidence obtained from the analysis of all fractions, it is suggested that etioporphyrin species are most likely entrapped in the molecular sieve type network of kerogen

On realise l'oxydation menagee par etapes, des kerogenes de schistes de Green River et de Monterey dans le but d'etudier la distribution en dimension des structures aliphatiques en chaine droite et le degre de reticulation des deux kerogenes