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Title: Searching for life on mars: Degradation of surfactant solutions used in organic extraction experiments
Authors: Court, R. W.
Sephton, M. A.
Sims, Mark R.
Cullen, D. C.
First Published: 5-Sep-2014
Publisher: Mary Ann Liebert for Astrobiology Society
Citation: Astrobiology, 2014, 14 (9), pp. 733-752
Abstract: Life-detection instruments on future Mars missions may use surfactant solutions to extract organic matter from samples of martian rocks. The thermal and radiation environments of space and Mars are capable of degrading these solutions, thereby reducing their ability to dissolve organic species. Successful extraction and detection of biosignatures on Mars requires an understanding of how degradation in extraterrestrial environments can affect surfactant performance. We exposed solutions of the surfactants polysorbate 80 (PS80), Zonyl FS-300, and poly[dimethylsiloxane-co-[3-(2-(2-hydroxyethoxy)ethoxy)propyl]methylsiloxane] (PDMSHEPMS) to elevated radiation and heat levels, combined with prolonged storage. Degradation was investigated by measuring changes in pH and electrical conductivity and by using the degraded solutions to extract a suite of organic compounds spiked onto grains of the martian soil simulant JSC Mars-1. Results indicate that the proton fluences expected during a mission to Mars do not cause significant degradation of surfactant compounds. Solutions of PS80 or PDMSHEPMS stored at-20°C are able to extract the spiked standards with acceptable recovery efficiencies. Extraction efficiencies for spiked standards decrease progressively with increasing temperature, and prolonged storage at 60°C renders the surfactant solutions ineffective. Neither the presence of ascorbic acid nor the choice of solvent unequivocally alters the efficiency of extraction of the spiked standards. Since degradation of polysorbates has the potential to produce organic compounds that could be mistaken for indigenous martian organic matter, the polysiloxane PDMSHEPMS may be a superior choice of surfactant for the exploration of Mars.
DOI Link: 10.1089/ast.2013.1105
ISSN: 1531-1074
eISSN: 1557-8070
Version: Post-print
Status: Peer-reviewed
Type: Journal Article
Rights: Archived with reference to publisher website. The final published version is available from Mary Ann Liebert, Inc., publishers at
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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