Vincent E. Modzeleski

Organic Compounds in Lunar Samples: Pyrolysis Products, Hydrocarbons, Amino Acids

Lunar fines and a chip from inside a rock pyrolyzed in helium at 700�C gave methane, other gases, and aromatic hydrocarbons. Benzene/methanol extracts of fines yielded traces of high molecular weight alkanes and sulfur. Traces of glycine, alanine, ethanolamine, and urea were found in aqueous extracts. Biological controls and a terrestrial rock, dunite, subjected to exhaust from the lunar module descent engine showed a different amino acid distribution. Interpretation of the origin of the carbon compounds requires extreme care, because of possible contamination acquired during initial sample processing.

An evaluation of pyrolytic techniques with regard to the Apollo 11, 12 and 14 lunar samples analyses

Two different pyrolysis techniques have been used in the analysis of lunar fines. The first technique involved pyrolysis at 700°C under an inert atmosphere in a flowing He system at normal pressure. The products were collected at liquid N2 temperature and then allowed to pass instantaneously into a combined capillary gas chromatograph-mass spectrometer. The second technique consisted of a vacuum pyrolysis where the sample was first degassed at 150°C and then pyrolyzed at 500°C and 1000°C consecutively. The products were again collected at liquid N2 temperature and then they were directly introduced to the ion source of the mass spectrometer through a modified gas inlet system.An evaluation of the two techniques based on control experiments has shown that the probability of secondary reactions is greater in the inert atmosphere pyrolysis method. Pyrolysis of benzene in He under atmospheric pressure at 600°C showed the presence of small quantities of biphenyl and trace amounts of naphthalene. Biphenyl pyrolyzed under vacuum at 600, 700, 800 and 900°C by passing through a hot zone containing a quartz wool plug showed the presence of a wide range of synthesis and breakdown products as the temperature increased.These experiments have shown the importance of taking into account the factors that influence pyrolytic degradation and/or the synthesis of products. These can be diffusion effects, involving sample size, sample form, pyrolysis pressure conditions; temperature, catalytic effects from the pyrolysis vessel, contamination, perhaps other factors. Pyrolysis is an effective method of analysis if used under carefully controlled conditions. Pyrolysis of Apollo 14 lunar fines and scrapings from an astronauts glove gave different products by mass spectrometry and showed different looking flaky materials upon scanning electron microscopy.