Fig. 4.

The 5C sugar acid enantiomer analysis of the Murchison meteorite. (A) A sample of Murch 39 (same sample as in Fig. 2B) analyzed immediately after extraction and preparation. (B) Murch 39-2, a separate portion of the Murch 39 extract, was stored until methods were developed to (reliably) separate enantiomers of arabinonic acid (Upper). The corresponding compounds in a sample of soil/dust (from the same sample as in Fig. 3E) (Lower). The change in d-l elution order of xylonic acid enantiomers from A was due to use of a different GC column (see SI Materials and Methods). A possible trace amount of lyxonic acid is present in the soil/dust sample; this would likely be due to the breakdown/oxidation of the common 6C sugar, galactose (see homologous relationships in Fig. S5) as none of the rare parent sugar of lyxonic acid, lyxose, was found. (C) The 5C acids of Murch 52. Methods for the consistent enantiomer separation of ribonic acid were not yet developed. No l enantiomers of lyxonic acid or xylonic acid were seen—likely due to overall low abundances. The change in d-l elution order of arabinonic acid enantiomers from that of B was due to use of a different GC column and compound derivative. Murch 39 samples were analyzed in their i-Pr/TFA forms; Murch 52 compounds were analyzed in ethyl esters (Et/TFA) forms (see SI Materials and Methods for derivatization details).