Abstract Lipid biomarkers are commonly used for tracking life through Earth’s history and are also gaining in importance in the search for extraterrestrial life. However, some lipids may also be formed in-situ via abiotic Fischer-Tropsch-type (FTT) reactions. These processes have been considered as a source of prebiotic organic matter. Here we report on a FTT synthesis experiment performed under hydrothermal conditions, focusing on more complex, previously undescribed FTT reaction products that may potentially mimic biological signals. The experiment was carried out in stainless steel reactors by heating aqueous solutions of oxalic acid mixed with montmorillonite to 175 °C for 3 days. Organic extracts of the products and extraction residues were analyzed by gas chromatography–mass spectrometry (GC–MS) and combustion-infrared detection, attenuated total reflectance Fourier transform infrared spectroscopy and pyrolysis GC–MS. FTT reactions led to a number of biomarker-like lipids such as linear and methyl-branched alkanes and alkanols as well as n-alkanoic acids. However, FTT reactions a priori produce unimodal chain length distributions and isomeric mixtures of methyl-branched compounds, as opposed to biolipids which typically show preferences of individual homologs and/or isomers. Experimental maturation of an immature kerogen demonstrated how these biological signatures may pass into unimodal distributions similar to FTT reaction products by thermal overprint. Therefore, discrimination of biologically derived compounds from FTT organics may become increasingly problematic with ongoing thermal maturation. Extraction residues of FTT reaction products contained organic material, possibly in form of an organic polymer. However, it remains to be tested whether these residual organics can evolve into kerogen-like material.

中文翻译：

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评估通过 Fischer-Tropsch 型反应形成的脂质的多样性

摘要 脂质生物标志物通常用于追踪地球历史上的生命，并且在寻找外星生命方面也越来越重要。然而，一些脂质也可以通过非生物费托型 (FTT) 反应原位形成。这些过程被认为是益生元有机物质的来源。在这里，我们报告了在水热条件下进行的 FTT 合成实验，重点是更复杂的、以前未描述的 FTT 反应产物，这些产物可能潜在地模仿生物信号。该实验在不锈钢反应器中进行，将混合有蒙脱石的草酸水溶液加热至 175 °C，持续 3 天。通过气相色谱-质谱（GC-MS）和燃烧-红外检测分析产物的有机提取物和提取残留物，衰减全反射傅里叶变换红外光谱和热解 GC-MS。FTT 反应产生了许多类似生物标志物的脂质，例如线性和甲基支链烷烃和烷醇以及正链烷酸。然而，FTT 反应先验地产生单峰链长分布和甲基支化化合物的异构混合物，这与通常表现出对单个同系物和/或异构体的偏好的生物脂质相反。未成熟干酪根的实验成熟证明了这些生物特征如何通过热套印进入类似于 FTT 反应产物的单峰分布。因此，随着持续的热成熟，从 FTT 有机物中区分生物衍生化合物可能会变得越来越成问题。FTT反应产物萃取残留物含有有机物，可能以有机聚合物的形式存在。然而，这些残留的有机物是否能演化成干酪根样物质还有待测试。