Carbonaceous chondrites insoluble organic matter

Cody, G. and Alexander, . M. O. D. (2005) NMR studies of chemical structural variation of insoluble organic matter from different carbonaceous chondrite groups. Geochimica et Cosmochimica Acta, 69, 1085—1097. 

Sephton et al. (1998, 1999, 2000) used hydrous pyrolysis followed by supercritical extraction to examine insoluble organic matter in Orgueil (CIl), Murchison (CM2), and Cold Bokkeveld (CM2). The hydrous pyrolysates obtained for the three meteorites displayed a remarkable degree of qualitative similarity suggesting that the macro-molecular materials in different carbonaceous chondrites are apparently composed of essentially the same aromatic structural units, predominantly one to three ring alkyl-substituted aromatic structures. Significant quantitative differences were observed, however, and these were interpreted as indications of the different parent body histories of the three meteorites (Sephton et al., 2000). 

Two analytical approaches have been adopted in attempts to obtain stable-isotopic information on insoluble organic matter in carbonaceous chondrites stepped-combustion analysis (e.g., Kerridge, 1983 Swart et al, 1983) and CSIA of pyrolysis products (e.g., Sephton et al, 1998). Stepped-combustion analysis has proved to be more successful in providing information on the major-elemental constituents of chondritic organic matter, i.e., carbon, hydrogen, nitrogen, and oxygen, whereas CSIA has started to yield detailed carbon isotopic and structural information. 

Komiya, M., Shimoyama, A. (1996) Organic compounds from insoluble organic matter isolated from the Murchison carbonaceous chondrite by heating experiments. Bulletin of the Chemical Society of lapan, 69, 53-58. 

About 70-95% of the organic matter in carbonaceous chondrites consists of an ill-defined, insoluble macromolecular material, often referred to as polymer or kerogen . A typical elemental composition for Murchison polymer (Hayatsu et al., 1980a), on a dry, ash-free basis, is C 76.5%, H 4.5%, N 2.4%, S 4.3%, and O 12.4% (by difference). 

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