Murchison Meteorite Analysis Using Tetramethylammonium Hydroxide (TMAH) Thermochemolysis Under Simulated Sample Analysis at Mars (SAM) Pyrolysis‐Gas Chromatography‐Mass Spectrometry Conditions.

The Sample Analysis at Mars (SAM) instrument aboard the Curiosity Rover at Gale crater can characterize organic molecules from scooped and drilled samples via pyrolysis of solid materials. In addition, SAM can conduct wet chemistry experiments which enhance the detection of organic molecules bound in macromolecules and convert polar organic compounds into volatile derivatives amenable to gas chromatography‐mass spectrometry analyses. Specifically, N‐tert‐butyldimethylsilyl‐N‐methyltrifluoroacetamide (MTBSTFA) is a silylation reagent whereas tetramethylammonium hydroxide (TMAH) is a thermochemolysis methylation reagent. Shortly after arriving at Mars, the SAM team discovered that at least one of the MTBSFTA cups was leaking, contributing to a continuous background inside SAM with the potential to interfere with future TMAH reactions. Therefore, here we characterized possible interactions between the two reagents to determine byproducts and implications for the detection of indigenous organics. SAM‐like pyrolysis experiments supplemented with flash pyrolysis were accordingly conducted with fragments of the Murchison meteorite as a reference for exogenous organic matter delivered to Mars. Flash TMAH experiments yielded various aromatic acids, dicarboxylic acids, and amino acids while SAM‐like pyrolysis presented mixtures of methylated and non‐methylated compounds due to decreased reaction efficiency at slower ramp rates. All experiments in the presence of simulated MTBSTFA vapor produced pervasive silylated byproducts which co‐elute and obscure the identification of Murchison‐derived compounds. Despite challenges, a significant diversity of pyrolyzates and TMAH derivatives could still be identified in flash pyrolysis in presence of MTBSTFA. However SAM‐like experiments with TMAH and MTBSTFA are hindered by both decreased methylation yields and additional co‐eluting compounds. Plain Language Summary: The Sample Analysis at Mars (SAM) instrument aboard the Curiosity Rover on Mars can detect and analyze organic molecules that might be used by life as we know it. SAM does this by heating scooped soil or drill samples in order to vaporize and uncover any organic content that might be present. In addition, SAM can detect different types of organics that have more direct similarities to those used by modern organisms by adding one of two different kinds of chemical reagents prior to heating. However, shortly after arriving at Mars, it was discovered that one type of reagent, called MTBSTFA, was leaking inside of SAM with the potential to eventually interfere with the other, called TMAH, whenever it might be utilized. This study therefore reports on the chemical interactions between the two reagents and how they might impact the detection of indigenous organics on Mars. We determined heating samples in the presence of both reagents produces a series of byproducts which obscure the identification of organic compounds of interest. Still, despite analytical challenges, it is possible SAM may detect different types of organics which have yet to be detected on Mars with TMAH despite interference from leaking MTBSTA. Key Points: TMAH experiments with Murchison meteorite produces various aromatic acids, dicarboxylic acids, and amino acidsSAM‐like TMAH pyrolysis presents mixtures of methylated and non‐methylated compounds due to decreased reaction yields at slower ramp ratesAll experiments with simulated MTBSTFA vapor produce byproducts that obscure the identification of Murchison‐derived compounds [ABSTRACT FROM AUTHOR]