APEX this week: Dr Kevin Devine on Martian soil analogue organic geochemistry

This week’s Astrobiology and Planetary Exploration (APEX) seminar features a talk by:

Dr Kevin Devine (London Metropolitan University):  An analytical protocol for the extraction, and identification of, aromatic carboxylic acids from a Mars soil analogue, containing perchlorate salts.

Abstract

The presence of perchlorate (ClO4-) salts in the soils of Mars at 0.6wt% complicates the search for indigenous organic compounds, particularly if they are present at low concentrations (<5.00ppm). Previous (Vikings 1&2, Phoenix) and current (Curiosity) missions have employed thermal volatilization-gas chromatography-mass spectrometry (TV-GC-MS) to search for organics. Perchlorate breaks down at temperatures above 300°C, yielding molecular chlorine (Cl2) and oxygen (O2) which rapidly reacts with any organics present to yield carbon dioxide, water and simple chlorinated organics. The latter were indeed detected by both Vikings and the SAM instrument on board Curiosity. 

Previously, we had speculated about what kind of organic compounds should be present in the Martian regolith, which result from the photochemical oxidation of organic materials delivered by meteoric impacts. In particular, the aromatic carboxylic acids mellitic acid, benzene-1,2-4,5 tetracarboxylic acid, trimesic acid and benzoic acid should be present at concentrations ranging from 10.0ppb to 50.0ppm. We describe herein an analytical protocol for the extraction of these aromatic acids at these concentrations from a Mars analogue soil, which contains 0.6wt% perchlorate salts. This analytical protocol involves solvent extraction, and, following derivatization of the extracted aromatic acids, their identification using gas chromatography-mass spectrometry (GC-MS).

Based on a paper by Kevin G Devine - 1 and Steven A Benner - 2

1 - School of Human Sciences, London Metropolitan University, London, United Kingdom.

2 - Foundation for Applied Molecular Evolution, 1309 Progress Blvd, Alachua FL-32615, Florida, USA

The full APEX programme for this term is now available at:

http://www.homepages.ucl.ac.uk/~ucfbiac/APEX.htm

As usual, everyone interested in these topics is welcome to attend.