GC-MS Method Development for Isomeric and Enantiomeric Analyses of Hydroxy Amino Acids in Carbonaceous Meteorites
Abstract
Carbonaceous chondrites are chemically primitive meteorites which contain volatile components such as water and organic matter. In particular, amino acids in carbonaceous chondrites have been extensively investigated, in part because of their potential role in chemical evolution and the origin of life. Analyses of meteoritic amino acids have shown that L-enantiomeric excesses for isovaline (up to 21%) may be due to the degree of aqueous alteration the meteorite parent body experienced (Elsila et al., 2016and references therein). It is possible that such L-amino acid enantiomeric excesses may have contributed to the origin of homochirality in life on Earth.
Recently, 9 new C3 and C4 hydroxy amino acids (HAAs) were discovered in the Murchison meteorite (Koga and Naraoka, 2017). HAAs were detected in the acid hydrolyzed, the extracted meteorite residue at similar or higher abundances compared to the hot water extract. Interestingly, non-protein aliphatic amino acids such as isovaline were detected at lower abundances in the extracted meteorite residue compared to the hot water extract. The presence of HAAs in the hydrolyzed meteorite residue indicates that HAAs may have a stronger affinity to minerals, than do aliphaticamino acids, like isovaline. Given that the isomeric and enantiomeric ratios of traditional meteoritic amino acids yield implications for parent body processes (e.g.,aqueous alteration), the recent discovery of meteoritic HAAs provides new and exciting opportunities to glean further insight into solar system history and the origin of life. However, methods to evaluate the isomeric distributions and enantiomeric excesses of HAAs are lacking. In this study, we are developing a gas chromatography-mass spectrometry (GC-MS) method to separate and detect structural isomers and enantiomers of C3 and C4 HAAs, totaling 24 different species. We apply this method to investigate the HAA distribution in both the water extract and the extracted residue of carbonaceous chondrite meteorites of different petrology and minerology. The results of this research will improve our understanding of 1) the abundances and distributions of HAA species detected and 2) how aqueous alteration may have influenced the formation mechanisms responsible for extraterrestrial HAAs and their enantiomeric compositions.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.P53G3055K
- Keywords:
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- 0406 Astrobiology and extraterrestrial materials;
- BIOGEOSCIENCESDE: 1028 Composition of meteorites;
- GEOCHEMISTRYDE: 3662 Meteorite mineralogy and petrology;
- MINERALOGY AND PETROLOGYDE: 5215 Origin of life;
- PLANETARY SCIENCES: ASTROBIOLOGY