Optimization of the in situ detection of Nucleobase on MOMA and SAM experiments
Résumé
Following the Sample Analysis at Mars (SAM) experiment onboard the Curiosity rover, the Mars Organic Molecule Analyzer (MOMA) experiment [1] onboard the future ExoMars 2020 mission will continue to investigate the organic composition of the martian subsurface. MOMA will have the advantage of extracting the sample from as deep as 2 meters below the martian surface where the deleterious effects of radiation and oxidation on organic matter are supposed to be minimized. To analyse the wide range of organic compounds (volatile and non-volatile compounds) potentially present in the martian soil, MOMA includes pyrolysis gas chromatography ion trap mass spectrometry (pyr-GC-ITMS). In order to analyse refractory organic compounds and chirality, samples which undergo GC-ITMS analysis may be derivatized beforehand, consisting in the reaction of the sample components with specific chemical reagents (MTBSTFA [2], DMF-DMA [3] or TMAH [4]). To prove the feasibility of the derivatization within the MOMA conditions we have adapted our laboratory procedure to the space conditions (temperature, time, pressure and size). The goal is to decrease our detection limits and increase the range of organic compounds that MOMA will be able to detect. Here, we only discuss the optimization of the thermochemolysis technique with TMAH on nucleobases.