2018 Fiscal Year Final Research Report
Challenge to 30 ppm TOC: Does carbon isotope analysis on pelagic chert possible only with popular method?
| Project/Area Number |
16K13897
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Stratigraphy/Paleontology
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| Research Institution | Kanazawa University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
松岡 篤 新潟大学, 自然科学系, 教授 (00183947)
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| Research Collaborator |
Goto Akiko S.
Hasebe Keiichiro
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | 炭素同位体 / 古環境 / 層序 / 対比 / チャート |
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| Outline of Final Research Achievements |
To achieve carbon isotope analysis on samples with very low TOC, the minimum amount of introduced carbon, and minimum TOC available for regular EA-IRMS analysis was investigated. Our regular EA-IRMS system could reproduce the results with 10 micro gram carbon or 0.025% TOC samples. Therefore, 0.025% TOC is concluded to be a minimum TOC for regular carbon isotope analysis with EA-IRMS system. For samples with TOC<0.025%, pre-sample treatment with hydrofluoric acid to reduce the volume of silicate is required for the use of EA-IRMS. Or the sample introduction portion of the analytical system should be reconstructed to reduce the dead volume.
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| Free Research Field |
古環境
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| Academic Significance and Societal Importance of the Research Achievements |
TOCが小さい試料を漠然とEA-IRMS法で他試料と同様に分析しても，一応のデータは出てしまう．それをそのまま分析値として用いる研究者が散見されたが，そのような分析に信頼性がないことが改めてわかった．一方，標準試料量を変えて特別に分析シーケンスを構築するなどすれば，0.025% TOCでも十分実用的なデータを出し得ることも分かった．それ以下のTOCであれば，分析装置だけでなくサンプルを包む錫箔に含まれる炭素の影響などもあり，EA-IRMS法での分析は困難であることが判った．TOC＝0.025%を目安としてフッ酸処理するものとしないものを見極めて，効率的に研究を進められるようになった．
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