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Thermal Desorption/GCMS Analysis of Astrobiologically Relevant Organic MaterialsSeveral macromolecular organic materials, both biologically-derived (type II kerogen and humic acid) and abiotic in origin (Murchison insoluble organic material, cyanide polymer, and Titan tholin) were subjected to thermal desorption using a Chromatoprobe attachment on a Varian Saturn 2000 GCMS system. Each sample was heated sequentially at 100, 200, and 300 C to release volatile components. The evolved compounds were then separated on a Supelco EC-1 dimethylsilica GC column and detected by the Saturn 2000 ion trap mass spectrometer. The various types of macromolecular organic material subjected to thermal desorption produced distinctly different GCMS chromatograms at each temperature, containing fractions of both low and high chromatographic mobility. The relative amounts of detectable volatiles released at each temperature also differed, with type II kerogen and cyanide polymer containing the highest percentage of low-temperature components. In all the samples, the highest yield of released compounds occurred at 300 C. Only cyanide polymer evolved a homologous hydrocarbon series, suggesting that it is the only material among those examined that contains a truly polymeric structure. Pyrolysis/gas chromatography/mass spectrometry has been used extensively for analysis of terrestrial organic macromolecular materials, and was also part of the instrument package on the Viking landers. Thorough analysis by pyrolysis usually employs temperatures of 500 C or higher, which for in situ analyses can be problematic given spacecraft power and materials constraints. This study demonstrates that heating of organic materials of astrobiological relevance to temperatures as low as 200-300 C for short periods releases volatile components that can be analyzed by gas chromatography and mass spectrometry. Even in the absence of full pyrolysis, useful chemical information on samples can be obtained, and materials from different biological and abiological sources can be distinguished. The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
Document ID
20020002123
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Paper
Authors
McDonald, Gene D.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Date Acquired
August 20, 2013
Publication Date
April 1, 2001
Publication Information
Publication: General Meeting of the NASA Astrobiology Insititute
Subject Category
Exobiology
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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