Analysis of Organics: interstellar synthesis and in situ chemical derivatization of amino acids
- Paper number
IAC-06-A1.6.03
- Author
Mr. Zachary Pozun, University of Pittsburgh, United States
- Coauthor
Ms. Shannon Tronick, United States
- Year
2006
- Abstract
It is generally accepted that exogenous organic matter was transported to Earth by meteorites and that amino acid synthesis most likely occurred in the aqueous phase. The delivery of organics to Mars complicates the search for evidence of past life; methods to differentiate between abiotically and biotically synthesized materials will become necessary. We have analyzed both synthesis and derivatization of amino acids. Our results indicate that simple amino acids may be synthesized from solid-state ices of hydrogen cyanide and water under proton irradiation, which is similar to the results of Bernstein et al. in 1992. Given the discovery of hydrogen cyanide in comet Hyakutake by Irvine et al. (1996), we sought to simulate cosmic ray irradiation of solid phase hydrogen cyanide in a water matrix. We deposited gaseous hydrogen cyanide and water mixtures onto a surface at 5 K under vacuum followed by proton irradiation from a Van de Graaff generator. In situ infrared spectroscopic analysis demonstrated that carbon dioxide was a clear by-product; however, residue analysis by HPLC indicates that simple amino acids were also formed as well. Due to the abundance of pre-biotic molecules in the ISM as well as radiation sources, our results indicate that solid-phase synthesis of amino acids in comets may complement aqueous phase synthesis on planetary bodies. Such abiotically-synthesized acids are, however, racemic mixtures, while amino acids created by biotic processes would be likely to favor one enantiomer. Thus, methods for derivatization of amino acids on planetary bodies will be necessary to differentiate between biotic and abiotic sources of amino acids. We advanced and improved the chemical derivatization methods summarized by Glavin and Buch. This liquid chemistry enables tagging of vital organics for analysis by GC-MS. The volatility of organics within the samples required a vacuum-line during the evaporative process as organics collected on a Pyrex cold finger. Atacama Desert soil and Nile Delta sediment samples were used as Mars analogues. Both amino acids and carboxylic acids were recovered in spiked and unspiked soil samples. Our results indicate vital organics can be extracted from soil samples after derivatization and sublimation. This supports the prospect for the search for life on Mars through in situ chemical derivatization as proposed in 2004 by Mahaffy et al. Given the likelihood of abiosynthesis and delivery of organics to planets, our methods for derivatizing amino acids in situ will aid in the differentiation between biotic and abiotic material.
- Abstract document
- Manuscript document
IAC-06-A1.6.03.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.