Application of Laser Desorption Mass Spectrometry (LDMS) to Cosmogeochemistry: Direct Analysis of Organic Compounds in Meteorites

Abstract

Organic compounds in meteorites are a key to understanding abiotic synthetic reactions, the cosmochemical carbon cycle, and the role that these processes might play in biogenesis. Although it was established over a century ago that some meteorites contain carbonaceous material which, in part, was in the form of organic compounds, their analyses has posed an extreme challenge due to the limited sample amount available and the possible contamination and chemical modification during sample storage and processing. In general, conventional geochemical approaches require several grams of sample and their chemical analysis is laborious, often involving a series of extraction, purification and identification steps. The use of laser desorption mass spectrometry (LDMS) allows for the direct analysis of a meteorite, which is non-destructive from a mineralogical standpoint and requires only sub-milligram quantities of meteorite material. LDMS involves the desorption of ‘intact’ organic compounds permitting their identification in a time-of-flight mass spectrometer. In this work, I have applied this method coupled with some simple extraction procedures and chemical syntheses to examine carbonaceous chondrites (Murchison and Allende) for the detection of polycyclic aromatic hydrocarbons (PAHs), kerogen-like material, fullerenes (C60 AND C70) and fulleranes (C70HX).