Organic matter detection on Mars by pyrolysis-FTIR: an analysis of sensitivity and mineral matrix effects

摘要

Pyrolysis-FTIR is a potentially attractive triage instrument that considers both the past habitability of the sample depositional environment and the presence of organic matter which may reflect actual habitation. An important consideration for triage protocols is the sensitivity of the instrumental method. Experimental data indicate pyrolysis-FTIR sensitivities for organic matter at the tens of parts per million level. The mineral matrix in which the organic matter is hosted also has an influence on organic detection and here to provide an insight to matrix effects we simply mix well characterised organic matter with dry minerals prior to analysis. During pyrolysis-FTIR, serpentinites that may be encountered in the Phyllosian Era lead to no negative effects on organic matter detection, sulfates that may be recovered from the Theiikian Era can lead to the combustion of organic matter, and palagonites that may represent samples from the Siderikian Era can lead to the chlorination of organic matter. Any negative consequences brought about by mineral effects can be mitigated by the correct choice of thermal extraction temperature. Our results offer an improved understanding of how pyrolysis-FTIR can perform during sample triage on Mars.