Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, California 91109, United States.
Anal Chem. 2021 Jul 13;93(27):9647-9655. doi: 10.1021/acs.analchem.1c02119. Epub 2021 Jun 29.
The in situ search for chemical signatures of life on extraterrestrial worlds requires automated hardware capable of performing detailed compositional analysis during robotic missions of exploration. The use of electrophoretic separations in this search is particularly powerful, enabling analysis of a wide range of soluble organic compounds potentially indicative of life, as well as inorganic compounds that can serve as indicators of habitability. However, to detect this broad range of compounds with a single electrophoresis instrument, a combination of different detection modes is required. For detection of any ionizable species, including organic compounds that do not participate in terrestrial biology (i.e., "unknown unknowns"), mass spectrometry (MS) is essential. Inorganic ions, or any dissolved charged species present, can be analyzed using capacitively coupled contactless conductivity detection (CD). Additionally, for the trace analysis of compounds of key interest to astrobiology (particularly, amino acids), laser-induced fluorescence (LIF) detection holds unique promise, due to the fact that it has the highest demonstrated sensitivity of any form of detection. Here, we demonstrate a fully automated, portable capillary electrophoresis analyzer that is capable of all these modes of detection. The prototype system developed here addresses the three most significant challenges for doing electrophoretic separations: precise sample injection, HV isolation, and automation of all operational steps. These key challenges were successfully addressed with the use of custom-designed rotor-stator valves with optimized operational sequences incorporating gas purging steps, rinses, and HV application.
在寻找外星世界的生命化学特征时，需要能够在机器人探索任务中执行详细成分分析的自动化硬件。在这种搜索中使用电泳分离特别强大，能够分析广泛的潜在生命指示的可溶性有机化合物，以及可用作宜居性指标的无机化合物。然而，为了使用单一电泳仪器检测到这广泛的化合物范围，需要结合不同的检测模式。对于任何可电离物质的检测，包括不参与地球生物学的有机化合物（即“未知的未知”），质谱（MS）是必不可少的。使用容性耦合非接触式电导检测（CD）可以分析无机离子或任何存在的溶解带电物质。此外，对于天体生物学中关键关注的化合物的痕量分析（特别是氨基酸），激光诱导荧光（LIF）检测具有独特的优势，因为它具有任何检测形式中最高的灵敏度。在这里，我们展示了一种完全自动化的、便携式毛细管电泳分析仪，该仪器能够实现所有这些检测模式。这里开发的原型系统解决了进行电泳分离的三个最重大的挑战：精确的样品进样、高压隔离和所有操作步骤的自动化。通过使用带有优化操作顺序的定制设计的转子-定子阀，成功解决了这些关键挑战，其中包括气体吹扫步骤、冲洗和高压应用。
