連続フロー型質量分析計を用いた炭酸塩および水試料の炭素・酸素安定同位体比測定

概要

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We verified the appropriate conditions and the precisions of stable isotopic analyses for carbonate and water samples using a mass spectrometer with Gas Bench. Standard deviation and reproducibility of the analyses are dependent on the amount of carbon dioxide obtained from samples, and are minimized when the amount of carbonate sample of 0.09-0.14 mg. Isotopic equilibrium is obtained in l hour at 50℃ after the reaction of carbonate and purified phosphoric acid. On these conditions, the reproducibility was±0.19‰ forδ^13C, and±0.22‰ for δ^18O(2SD). In the case of water samples, the appropriate sample amount was 0.75-1.0 mL for seawater, and 0.5 mL for calcareous freshwater that includes 3-4 mM of dissolved inorganic carbon. Reproducibility of ±0.04‰ (2SD) is gained for δ^13C after the reaction for 20 hours at 25℃. Oxygen isotope reaches the equilibrium in 24 hours after the reaction, which reveals the reproducibility of ±0.18‰(2SD). Standard deviation and reproducibility in any cases are within a required level for geoscientific researches on the marine and terrestrial specimens.
九州大学大学院比較社会文化学府,Graduate School of Social and Cultural Studies, Kyushu Universityの論文
2009-03-25