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Lookup NU author(s): Dr Geoffrey AbbottORCiD,
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The distribution of the free and bound hopanoic acids in both unheated and heated (350 degreesC for 50 h) kerogens, isolated from the Messel oil shale, were analyzed by GC-MS. The bound acids were released by subjecting the kerogen to three different treatments, namely, thermochemolysis in the presence of tetramethylammonium hydroxide (TMAH), as well as basic and acidic hydrolyses. All of these methods gave a series of hopanoic acids ranging from C-30 to C-34, in which the biological 17 beta, 21 beta (H) configuration is prominent. Both 22R and 22S epimers are present for the C30 acid, whereas the others are dominated by the sidechain 22R-configuration. Thermochemolysis in the presence of TMAH was the most efficient in releasing kerogen-bound hopanoids. Following pyrolysis, the acids are generated and released into the free fraction with apparent epimerization occurring at C-17, C-21, and C-22. The bound hopanoic acids may be both chemically bonded as well as possibly being physically encapsulated within the macromolecular fraction of sedimentary organic matter. They are therefore either generated by breaking the bonds which bind them to the kerogen or they are released as a result of the macromolecular cage being broken apart. (C) 2001 Wiley-Liss, Inc.
Author(s): Abbott GD, Bashir FZ, Sugden MA
Publication type: Article
Publication status: Published
ISSN (print): 0899-0042
ISSN (electronic): 1520-636X
Notes: Special Issue Second International Symposium on Biological Chirality
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