Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, 8-10 Rue Joliot-Curie, 91190, Gif-sur-Yvette, France.
Department of Geological Sciences, University of Florida, Gainesville, FL, 32611, USA.
Talanta. 2023 May 15;257:124283. doi: 10.1016/j.talanta.2023.124283. Epub 2023 Feb 3.
One of the main objectives of present and future space exploration missions dedicated to astrobiology is the detection of organic molecules of interest for life (e.g. amino and fatty acids). With this aim, a sample preparation and a gas chromatograph (connected to a mass spectrometer) are generally used. To date, tetramethylammonium hydroxide (TMAH) has been the first and only thermochemolysis reagent to be used for in situ sample preparation and chemical analysis of planetary environments. Although TMAH is widely used in terrestrial laboratories, numerous applications also leverage other thermochemolysis reagents that may be more relevant than TMAH to meet both scientific and technical objectives of space instrumentation. The present study compares the performance of tetramethylammonium hydroxide (TMAH), trimethylsulfonium hydroxide (TMSH), and trimethylphenylammonium hydroxide (TMPAH) reagents on molecules of interest to astrobiology. The study focuses on the analyses of 13 carboxylic acids (C-C), 17 proteinic amino acids, and the 5 nucleobases. Here we report the derivatization yield without stirring or adding solvents, the detection sensitivity with mass spectrometry, and the nature of the degradation products from the reagents produced during pyrolysis. We conclude that TMSH and TMAH are the best reagents for analyzing carboxylic acids and nucleobases. Amino acids are not relevant targets for a thermochemolysis over 300 °C as they are degraded and showed high limits of detection. As TMAH, and probably TMSH, meet the space instrumentation requirements, this study informs sample treatment approaches prior to GC-MS analysis in in situ space studies. The thermochemolysis reaction using TMAH or TMSH is also recommended for space return missions to extract organics from a macromolecular matrix, derivatize polar or refractory organic targets, and volatilize with the fewest organic degradations.
目前和未来专注于天体生物学的太空探索任务的主要目标之一是检测对生命有意义的有机分子（例如氨基酸和脂肪酸）。为此，通常使用样品制备和气相色谱仪（与质谱仪相连）。迄今为止，四甲基氢氧化铵（TMAH）一直是用于原位样品制备和行星环境化学分析的第一种也是唯一的热化学分解试剂。尽管 TMAH 在地球实验室中得到了广泛应用，但许多应用还利用了其他可能比 TMAH 更相关的热化学分解试剂，以满足太空仪器的科学和技术目标。本研究比较了四甲基氢氧化铵（TMAH）、三甲基硫酸氢盐（TMSH）和三甲基苯铵氢氧化物（TMPAH）试剂对天体生物学感兴趣的分子的性能。该研究重点分析了 13 种羧酸（C-C）、17 种蛋白质氨基酸和 5 种核苷酸碱基。在这里，我们报告了无需搅拌或添加溶剂的衍生化产率、质谱检测灵敏度以及热解过程中试剂产生的降解产物的性质。我们得出结论，TMSH 和 TMAH 是分析羧酸和核苷酸碱基的最佳试剂。氨基酸不是 300°C 以上热化学分解的相关目标，因为它们会降解并显示出高检测限。由于 TMAH （可能还有 TMSH）符合太空仪器的要求，因此本研究为原位太空研究中的 GC-MS 分析之前的样品处理方法提供了信息。还建议使用 TMAH 或 TMSH 进行热化学分解反应，以从高分子基质中提取有机物、衍生极性或难挥发的有机靶标，并以最少的有机降解物挥发。
