Assessing the diversity of lipids formed via Fischer-Tropsch-type reactions
Assessing the diversity of lipids formed via Fischer-Tropsch-type reactions
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DOI：
10.1016/j.orggeochem.2018.02.012
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发表时间：
2018-05-01
影响因子：
3
通讯作者：
Thiel, Volker
中科院分区：
文献类型：
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作者：
Missbach, Helge;Schmidt, Burkhard C.;Thiel, Volker
脂质生物标志物通常用于跟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。这些过程被认为是前生物有机物质的来源。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，可能潜在地模仿生物信号。实验在不锈钢反应器中通过将与蒙脱石混合的草酸水溶液加热至175 ℃持续3天来进行。采用气相色谱-质谱（GC-MS）、燃烧红外检测、衰减全反射傅里叶变换红外光谱（ATFT）和热解GC-MS对产物和萃取残留物的有机萃取物进行了分析。FTT反应产生了一些生物标志物样脂质，如直链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体混合物，与通常显示个体同系物和/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叠印进入类似于FTT反应产物的单峰分布。因此，从FTT有机物生物衍生的化合物的歧视可能会变得越来越多的问题与正在进行的热成熟。FTT反应产物的浸提残留物含有有机材料，可能为有机聚合物形式。然而，这些残留的有机物是否能演变成干酪根样物质仍有待测试。(C)2018爱思唯尔有限公司版权所有。
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 degrees C for 3 days. Organic extracts of the products and extraction residues were analyzed by gas chromatography-mass spectrometry (GC-MS) and combustioninfrared 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. (C) 2018 Elsevier Ltd. All rights reserved.