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The products of stepwise alkaline permanganate degradation of kerogen from Estonian kukersite are considered as possible derivatives of preserved biostructures of the microfossil G. prisca . The aliphatic component, constituting ca. 25% of the matrix, was oxidized giving n -α,ω-alkyldicarboxylic (C 4 –C 15 ), α-methyldicarboxylic (C 7 –C 12 , C 14 , C 15 ), branched dicarboxylic (C 5 –C 10 ), and n- alkylmonocarboxylic (C 14 –C 18 , C 22 ) acids. When compared with previously studied kerogens, the oxidation products of kukersite differ (short carbon chains 20 , dicarboxylic acids' maximum shifted towards smaller number of carbon atoms, and a much higher degradation “loss”) indicating that the aliphatic moieties in the kukersite kerogen correspond to unusually short carbon chains with significant alkylsubstitution. The occurrence of such moieties is in agreement with the supposed feature of the aliphatic components of the resistant biopolymer comprising G . prisca cell walls. Hetero- and alicyclic structures constituting ca. 10% of the matrix yielded C 6 –C 18 alkyltri- and C 8 –C 14 alkyltetracarboxylic acids. The similarities in the distributions of alkyltri- and tetracarboxylic acids (C n tri vs. C n −3 tetra ) suggested that the precursor moieties of those acids had the same source. Furthermore, similarities in the distribution of n -α,ω-alkyldicarboxylic and alkyltetracarboxylic acids (C n di vs. C n +1 tetra ) may mean that some, at least, of these structures were produced diagenetically from terminally bifunctional alkyl-chains in preserved biopolymers. Alkylsuccinic acids (C 10 , C 11 and C 15 ) and alkylsuccinic acids containing an O-functional group in the alkyl chain (C 11 –C 20 ), were obtained in appreciable yield (ca. 4% w/w of the matrix). Their precursor moieties, although still unknown, were most probably structural building blocks of the microfossil. Benzenediol derivatives, characteristic of kukersites, were not observed as they are not amenable to analysis using the methods employed in this study. |
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