In situ instrumentation that can detect amino acids at parts-per-billion concentration levels and distinguish an enantiomeric excess of either d- or l-amino acids is vital for future robotic life-detection missions to promising targets in our solar system. In this article, a novel chiral amino acid analysis method is described, which reduces the risk of organic contamination and spurious signals from by-products by avoiding organic solvents and organic additives. Online solid-phase extraction, chiral liquid chromatography, and mass spectrometry were used for automated analysis of amino acids from solid and aqueous environmental samples. Carbonated water (pH ∼3, ∼5 wt % CO₂ achieved at 6 MPa) was used as the extraction solvent for solid samples at 150°C and as the mobile phase at ambient temperature for chiral chromatographic separation. Of 18 enantiomeric amino acids, 5 enantiomeric pairs were separated with a chromatographic resolution >1.5 and 12 pairs with a resolution >0.7. The median lower limit of detection of amino acids was 2.5 μg/L, with the lowest experimentally verified as low as 0.25 μg/L. Samples from a geyser site (Great Fountain Geyser) and a geothermal spring site (Lemon Spring) in Yellowstone National Park were analyzed to demonstrate the viability of the method for future in situ missions to Ocean Worlds.

中文翻译：

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在不使用有机溶剂或衍生化的情况下提取和分离用于海洋世界生命探测的手性氨基酸

可以检测十亿分之一浓度水平的氨基酸并区分对映体过量的d或l氨基酸的原位仪器对于未来机器人生命探测任务对太阳系中的有希望的目标至关重要。在本文中，描述了一种新的手性氨基酸分析方法，该方法通过避免使用有机溶剂和有机添加剂来降低有机污染和副产品虚假信号的风险。在线固相萃取、手性液相色谱法和质谱法用于自动分析固体和水性环境样品中的氨基酸。碳酸水（pH ∼3, ∼5 wt % CO ₂在 6 MPa 下达到）用作 150°C 下固体样品的萃取溶剂，并用作室温下手性色谱分离的流动相。在 18 个对映体氨基酸中，5 个对映体对以 >1.5 的色谱分辨率分离，12 个对映体对以 >0.7 的分辨率分离。氨基酸检测的中值下限为2.5 μg/L，经实验验证的最低值低至0.25 μg/L。分析了来自黄石国家公园间歇泉站点（Great Fountain Geyser）和地热泉站点（柠檬泉）的样本，以证明该方法在未来对海洋世界进行原位任务时的可行性。