Koudai Taguchi1, Tomonari Yamamoto1, Mayuko Nakagawa1,2, Alexis Gilbert1,2, Yuichiro Ueno1,2,3. 1. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo, 152-8551, Japan. 2. Earth-Life Science Institute (WPI-ELSI), Tokyo Institute of Technology, Meguro, Tokyo, 152-8550, Japan. 3. Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho, Yokosuka, 237-0061, Japan.
Abstract
RATIONALE: Doubly substituted isotope species ("clumped" isotopes) can provide insights into the biogeochemical history of a molecule, including its temperature of formation and/or its (bio)synthetic pathway. Here, we propose a new fluorination method for the measurement of 13 C-13 C species in C2 molecules using a conventional isotope ratio mass spectrometer. Target molecules include ethane, ethene and ethanol. METHODS: 13 C-13 C isotope species in C2 molecules were measured as C2 F6 using a conventional isotope ratio mass spectrometer. Ethane and ethene are directly fluorinated to C2 F6 . Ethanol is measured after dehydration to ethene and subsequent fluorination of the latter. The method enables the measurement of the Δ13 C13 C values normalized against a reference working standard. RESULTS: The reproducibility of the whole protocol, including chemical modification steps and measurement of C2 F6 isotopologues, is better than ±0.14‰ for all the compounds. Ethane from natural gas samples and biologically derived ethanol show a narrow range of Δ13 C13 C values, varying from 0.72‰ to 0.90‰. In contrast, synthetic ethanol as well as putative abiotic ethane show Δ13 C13 C values significantly different from this range with values of 1.14‰ and 0.25‰, respectively. CONCLUSIONS: The method presented here provides alternative means of measuring 13 C-13 C species to that using high-resolution mass spectrometry. Preliminary data from natural and synthetic molecules re-emphasizes the potential of 13 C clumped isotope species as a (bio)marker.
RATIONALE: Doubly substituted isotope species ("clumped" isotopes) can provide insights into the biogeochemical history of a molecule, including its temperature of formation and/or its (bio)synthetic pathway. Here, we propose a new fluorination method for the measurement of 13 C-13 C species in C2 molecules using a conventional isotope ratio mass spectrometer. Target molecules include ethane, ethene and ethanol. METHODS:13 C-13 C isotope species in C2 molecules were measured as C2 F6 using a conventional isotope ratio mass spectrometer. Ethane and ethene are directly fluorinated to C2 F6 . Ethanol is measured after dehydration to ethene and subsequent fluorination of the latter. The method enables the measurement of the Δ13 C13 C values normalized against a reference working standard. RESULTS: The reproducibility of the whole protocol, including chemical modification steps and measurement of C2 F6 isotopologues, is better than ±0.14‰ for all the compounds. Ethane from natural gas samples and biologically derived ethanol show a narrow range of Δ13 C13 C values, varying from 0.72‰ to 0.90‰. In contrast, synthetic ethanol as well as putative abiotic ethane show Δ13 C13 C values significantly different from this range with values of 1.14‰ and 0.25‰, respectively. CONCLUSIONS: The method presented here provides alternative means of measuring 13 C-13 C species to that using high-resolution mass spectrometry. Preliminary data from natural and synthetic molecules re-emphasizes the potential of 13 C clumped isotope species as a (bio)marker.