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2008
Botta, O, Martins Z, Emmenegger C, Dworkin JP, Glavin DP, Harvey RP, Zenobi R, Bada JL, Ehrenfreund P.  2008.  Polycyclic aromatic hydrocarbons and amino acids in meteorites and ice samples from LaPaz Icefield, Antarctica. Meteoritics & Planetary Science. 43:1465-1480. AbstractWebsite

We have analyzed ice samples and meteorites from the LaPaz region of Antarctica to investigate the composition of polycyclic aromatic hydrocarbons (PAHs) and amino acids with the goal to understand whether or not there is a compositional relationship between the two reservoirs. Four LL5 ordinary chondrites (OCs) and one CK carbonaceous chondrite were collected as part of the 2003/2004 ANSMET season. Ice samples collected from directly underneath the meteorites were extracted. In addition, exhaust particles from the snowmobiles used during the expedition were collected to investigate possible contributions from this source. The meteorite samples, the particulate matter and solid-state extracts of the ice samples and the exhaust filters were subjected to two-step laser mass spectrometry (L2MS) to investigate the PAH composition. For amino acids analysis, the meteorites were extracted with water and acid hydrolyzed, and the extracts were analyzed with offline OPA/NAC derivatization combined with liquid chromatography with UV fluorescence detection and time of flight mass spectrometry (LC-FC/ToF-MS). PAHs in the particulate matter of the ice were found to be qualitatively similar to the meteorite samples, indicating that micron-sized grains of the meteorite may be embedded in the ice samples. The concentration levels of dissolved PAHs in all the ice samples were found to be below the detection limit of the L2MS. The PAH composition of the snowmobile exhaust is significantly different to the one in particulate matter, making it an unlikely Source of contamination for Antarctic meteorites. The amino acids glycine, beta-alanine and gamma-amino-n-butyric acid that were detected at concentrations of 3 to 19 parts per billion (ppb) are probably indigenous to the Antarctic meteorites. Some of the LaPaz ice samples were also found to contain amino acids at concentration levels of 1 to 33 parts per trillion (ppt), in particular alpha-aminoisobutyric acid (AIB), an abundant non-protein amino acid of extraterrestrial Origin found in some carbonaceous chondrites. We hypothesize that this amino acid could have been extracted from Antarctic micrometeorites and the particulate matter of the meteorites during the concentration procedure of the ice samples.

1992
Zenobi, R, Philippoz JM, Zare RN, Wing MR, Bada JL, Marti K.  1992.  Organic-Compounds in the Forest Vale, H4 Ordinary Chondrite. Geochimica Et Cosmochimica Acta. 56:2899-2905.   10.1016/0016-7037(92)90366-q   AbstractWebsite

We have analyzed the H4 ordinary chondrite Forest Vale for polycyclic aromatic hydrocarbons (PAHs) using two-step laser mass spectrometry (L2MS) and for amino acids using a standard chromatographic method. Indigenous PAHs were identified in the matrices of freshly cleaved interior faces but could not be detected in pulverized silicates and chondrules. No depth dependence of the PAHs was found in a chipped interior piece. Amino acids, taken from the entire sample, consisted of protein amino acids that were nonracemic, indicating that they are terrestrial contaminants. The presence of indigenous PAHs and absence of indigenous amino acids provides support for the contention that different processes and environments contributed to the synthesis of the organic matter in the solar system.

1991
Wing, MR, Bada JL.  1991.  Geochromatography on the Parent Body of the Carbonaceous Chondrite Ivuna. Geochimica Et Cosmochimica Acta. 55:2937-2942.   10.1016/0016-7037(91)90458-h   AbstractWebsite

Ivuna, a CI carbonaceous chondrite, has been found to contain abundant amounts of the three-ring polycyclic aromatic hydrocarbons (PAHs) phenanthrene/anthracene, but no detectable levels of the two- and four-ring PAHs naphthalene and pyrene/fluoranthene. Either the three-ring PAHs in Ivuna were synthesized in a process that did not produce the two- or four-ring PAHs, or all these compounds were synthesized together and subsequently separated. Thermodynamical considerations and studies of hydrocarbon pyrolysis and combustion do not support the former possibility. Ivuna and other CI carbonaceous chondrites are known to have been extensively altered by water. The aqueous solubilities suggest that some PAHs would have been mobilized during the aqueous alteration phase in carbonaceous meteorite parent bodies. In a model geochromatography experiment, naphthalene, phenanthrene, and pyrene were partially resolved at a low pressure and flow rate utilizing columns containing crushed serpentine or beach sand, and water for elution. This laboratory geochromatography experiment suggests that complete separation of PAHs could be expected to occur in the parent body of CI carbonaceous chondrites. Such processes on Earth are known to lead to the formation of hydrothermal PAH minerals such as pendletonite. It is proposed that aqueous fluids driven by heat in the parent body of Ivuna migrated from the interior to the surface, in the process transporting, separating, and concentrating PAHs at various zones in the parent body.