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Pizzarello et al. 10.1073/pnas.0709909105. |
Fig. 3. Total-ion chromatogram of the GRA 95229 meteorite unhydrolyzed water extract showing the elution L- and D-isovaline in relation to D-alanine.
Fig. 4. GC isotope ratio MS of a GRA 95229 unhydrolyzed water extract sample containing six-carbon isoleucine, alloisoleucine and leucine (b) and of an alloisoleucine/isoleucine standard (c). The peak following that of D-leu is an unidentified N-substituted six-carbon amino acid. (a) The 45/44 trace and the start- and end-points used for each isotopic measurement are shown.
SI Text
Amino acids. Results for amino acids are shown in SI Table 3. As for Murchison and other CM2 chondrites analyzed so far, many more GRA 95229 amino acids than the ones listed were made evident by typical mass fragmentograms but were not identified for lack of reference standards.
The most abundant of these are the cyclic compounds, most of which appear to have a secondary nitrogen in the ring and are more abundant than the open chain species at higher chain lengths. Amino acids identified in Murchison but not listed for the GRA 95229 meteorite, such as C6 2-amino-2-ethylbutanoic and pseudoleucine or other non-a C5- and dicarboxylic amino acids, were searched for but not found in this sample.
Monocarboxylic Acids, Hydroxy Acids, Dicarboxylic Acids, and Amines. Monocarboxylic acids, hydroxy acids, and dicarboxylic acids identified in the GRA 95229 meteorite are shown in SI Tables 4, 5, and 6, respectively. Alkyl amines identified in the GRA 95229 meteorite are shown in SI Table 7. Ammonia is not listed in the table and was found present in the amount of 18.85 mm/g of meteorite. Several more amines than the ones listed were observed in the analyses but could not be identified for the lack of reference standards. A series of methylpyridines were also observed in the amine sample.
Hydrocarbons. In contrast to the abundance of individual compounds found in the water extract, hydrocarbons were found present in far lower amount in the GRA 95229 DCM/MeOH extract. For the aliphatic compounds, the gas-chromatogram is dominated by numerous, unresolved, trace amounts of branched and cyclic (and/or olefinic) species; the saturated molecules predominate in the first part of the chromatogram (at lower molecular weight), whereas the cyclic/unsaturated do so in the later part. Linear hydrocarbons with C14, C15, and C16 chain lengths were observed, but they appear to decline to a small C17, and vanishing low C18 peaks and are not seen at higher molecular weight. It is possible that smaller straight-chain hydrocarbons were present in the extract but evaporated upon drying. Polycyclic aromatic hydrocarbons identified in the GRA 95229 meteorite are shown in SI Table 8. Other O-, N-, and S-containing PAHs identified in Murchison were searched for but not found.
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