Compound-specific carbon isotope analysis of low-molecular organic acids and its application to geochemical samples

低分子有机酸的化合物特异性碳同位素分析及其在地球化学样品中的应用

• 批准号: 09554030
• 负责人: NARAOKA Hiroshi
• 金额: $ 6.08万
• 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 (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09554030/
• 关键词: low-molecular wieght organic acids; carbon isotope ratios; monocarboxylic acids; dicarboxylic acids; oil field water; pyrolysis; GC; C; IRMS; 降水; ケロジェン; クラッキングモデル; 速度論的同位体効果; 同位体平衡; ヒドロキシカルボン酸; 分子レベル炭素同位体比; 固相マイクロ抽出

Carbon isotopic compositions of individual low-molecular carboxylic acids such as acetic acid and oxalic acid were measured on sub-nano mol level using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). While free monocarboxylic acids are hard to oxidaze to COィイD22ィエD2 quantatively in a micro volume furnace, decyl ester derivatives of the acids are easier to convert to COィイD22ィエD2. Also the dicarboxylic acids were derivatized to dibutyl esters for the GC/C/IRMS measurement. Using internal isotopic standards of n-alkanes, analytical precision was within ±0.3‰. Isotopic mass balance calculation shows that the corrected analytical precisions are 2-3‰ for the free acids.Carbon isotopic compositions of individual organic acids in oil-field waters from Sarukawa Oil Field (Funakawa Formation, Miocene) in the northern Japan. The δィイD113ィエD1C values of acetic acid and propanoic acid range widely from -61 to -23‰ (relative to PDB) and -from -51 to -28‰, respectively. The low-molecular acids are more depleted in ィイD113ィエD1C than the bulk crude oil (ca. -22‰) produced from the same formation. The δィイD113ィエD1C values of acetic acid correlate well (rィイD12ィエD1=0.94) with those of propanoic acid (n=7 with one exception). Isotopically heavy acids tend to be observed in higher temperature water. In addition we conducted hydrous pyrolysis of kerogen purified from the same formation. The isotopic composition of acetic acid and propanoic acid produced by the pyrolysis experiment is plotted on the correlation that is observed in natural samples. These results suggest that the low-molecular monocarboxylic acids are produced by cracking of kerogen.

采用气相色谱/燃烧/同位素比值质谱（GC/C/IRMS）技术，在亚纳摩尔水平上测定了乙酸和草酸等低分子羧酸的碳同位素组成。虽然游离的一元羧酸在微体积炉中难以氧化成CO二氢D22二氢D2量子数，但酸的癸酯衍生物更容易转化成CO二氢D22二氢D2。此外，将二羧酸衍生为三羧酸酯用于GC/C/IRMS测量。采用正构烷烃同位素内标，分析精度在±0.3‰以内。同位素质量平衡计算表明，游离酸的校正分析精度为2-3‰。日本北方猿川油田中新统船川组油田水沃茨的碳同位素组成。乙酸和丙酸的δ ε D113 ε D1C值分别为-61至-23‰（相对于PDB）和-51至-28‰。低分子酸在原油D113中的贫化程度高于散装原油（约100%）。-22‰）产自同一地层。乙酸的δ ε D113 ε D1C值与丙酸的δ ε D12 ε D1值相关性良好（r ε D12 ε D1=0.94）（n=7，有一个例外）。同位素重酸倾向于在高温水中观察到。此外，我们还对从同一地层中提纯的干酪根进行了水合热解。由热解实验产生的乙酸和丙酸的同位素组成绘制在天然样品中观察到的相关性上。这些结果表明，低分子量的一元羧酸是由干酪根裂解产生的。

项目成果

H. Naraoka, K. Yamada and R. Ishiwatari: "Recent sedimentary hopanoids in the western north Pacific alongside the Japanese Islands ; their concentrations and carbon isotopic compositions"Organic Geochemistry. (in press). (2000)

H. Naraoka、K. Yamada 和 R. Ishiwatari：“北太平洋西部日本列岛最近沉积的藿香类化合物；它们的浓度和碳同位素组成”有机地球化学。

H.Naraoka, K.Yamada ら: "Recent sedimentary hopanoids in the western north Pacific alongside the Japanese Islands ; their concentrations and car bon isotopic"Organic Geochemistry. 31(印刷中). (2000)

H.Naraoka、K.Yamada 等人：“日本群岛西部北太平洋最近沉积的藿香类化合物；它们的浓度和碳同位素”有机地球化学 31（出版中）。

H. Naraoka, K. Yamada and R. Ishiwatari: "Compound-specific isotope analysis of light elements using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) and its application to geochemistry"Chikyuukagaku (Geochemistry). 31( in Japanes

H. Naraoka、K. Yamada 和 R. Ishiwatari：“使用气相色谱/燃烧/同位素比质谱 (GC/C/IRMS) 进行轻元素的化合物特异性同位素分析及其在地球化学中的应用”Chikyuukagaku（地球化学）。

H.Naraoka ら: "Molecular distribution of monocarboxylic acids in Asuka carbonaceous chondrites from Antarctiea" Origins of Life and Evolution of the Biosphere. (印刷中). (1998)

H. Naraoka 等人：“南极洲飞鸟碳质球粒陨石中一元羧酸的分子分布”《生命起源与生物圈进化》（1998 年出版）。