Organic chemical analysis on a microscopic scale using two-step laser desorption/laser ionization mass spectrometry

The distribution of polycyclic aromatic hydrocarbons (PAHs) in the Allende meteorite has been measured using two-step laser desorption/laser multiphoton ionization mass spectrometry. This method enables in situ analysis with a spatial resolution of 1 millimeter or better of selected organic molecules. We present results showing that PAH concentrations are locally high compared to the average concentration found by analysis of pulverized samples, and are found primarily in the fine grained matrix; no PAHs were detected in the interiors of individual chondrules at our detection limit of about 0.05 parts per million. We have recently extended the spatial resolution of this instrument to 40 microns.