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Compound-specific stable hydrogen isotope analysis of natural samples in nano-molar levels and its application to earth environmental sciences

纳摩尔水平天然样品的化合物特异性稳定氢同位素分析及其在地球环境科学中的应用

基本信息

批准号：
12359003
负责人：
NARAOKA Hiroshi
金额：
$ 21.15万
依托单位：
TOKYO METROPOLITAN UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

Compound-specific hydrogen isotope measurement has been developed at sub-nano molar level using gas chromatography/pyrolysis/isotope ratio mass spectrometry (GC/pyrolysis/IRMS). Isotopic calibration and sample preparation including derivatization of unvolatile compounds and separation of co-eluted compounds by silica gel chromatography were also established for more precise isotope measurement. Finally, it is successful to determine a OD value of natural samples with precision of less than 5‰ using ・0ng hydrogen-containing organic compound. We applied the established method to determine δD values of n-alkanes, n-alkanoic acids, n-alkanols and sterols of biological materials and sediments, in order to discuss their isotope fractionation mechanisms during different biosynthetic pathways as well as their source, diagenetic effects and transportation processes in sediments. We also conducted the δD measurement of polycyclic aromatic hydrocarbons such as pyrene and fluoranthene in carbonaceous chondrites to find different the δD value in spite of their structural isomers each other (C_<16>H_<10>). In addition, hydrogen isotope exchange of pyrene and fluoranthene occurred in hydrothermal solutions under acidic condition, where where hydrogens have exchanged more easily between pyrene and water relative to between fluoranthene and water. The kinetically different behavior between pyrene and fluoranthene coincides with the two-series (pyrene-series and fluoranthene-series) PAH formation mechanisms in carbonaceous chondrites inferred from carbon isotopic compositions of PAH.Originally this reserch project was planned for 4 years (2000-2003 FY). However, since this project has successfully continued to a new research project as titled "Multi-stable isotope systematics of individual organic compounds in cosmogeochemical samples", this project ended up to make a final report.

采用气相色谱/热解/同位素比值质谱法（GC/Pyrolysis/IRMS），在亚纳米摩尔水平上对化合物的氢同位素进行了测量。同位素校准和样品制备，包括衍生化的非挥发性化合物和共洗脱化合物的硅胶色谱分离也建立了更精确的同位素测量。最后，用·0 ng含氢有机物成功地测定了天然样品的OD值，其精密度小于5‰。应用建立的方法测定了生物样品和沉积物中正构烷烃、正构烷酸、正构烷醇和甾醇的δD值，探讨了它们在不同生物合成途径中的同位素分馏机制，以及它们的来源、成岩作用和在沉积物中的运移过程。本文还对多环芳烃如芘和荧蒽在碳质岩中的δD值进行了测量，发现它们的δD值随结构异构体（C_<16>H_<10>）的不同而不同。此外，在酸性条件下，水热溶液中芘和荧蒽发生了氢同位素交换，其中芘和水之间的氢同位素交换比荧蒽和水之间的氢同位素交换更容易。芘和荧蒽在动力学上的不同行为与从PAH碳同位素组成推断的两系列（芘系列和荧蒽系列）PAH在碳质岩中的形成机制相吻合。然而，由于该项目已成功地延续到一个新的研究项目“宇宙地球化学样品中单个有机化合物的多稳定同位素系统学”，该项目最终完成了最终报告。