【摘要】 用连续流同位素质谱对水样中溶解无机碳含量和碳同位素组成的测量方法进行了研究,使用德国Finnigan公司DeltaPlusXP同位素质谱仪和GasBenchⅡ在线制样装置对实验室制备的四个实验室标准进行了反应流程、平衡时间、信号强度、数据精度、标准稳定性等检测,结果显示平衡时间大于4h检测信号达到稳定,同时发现44CO2信号强度和水样中溶解无机碳(DIC)浓度具有很好的相关性,因此可以利用信号强度来计算原样品中的DIC浓度。在四个实验室标准中,由NaHCO3配置的标准具有非常好的稳定性和精度,可以作为测试的工作标准。本方法测量水样中溶解无机碳的δ13C分析精度为0.1‰。本方法可以广泛应用于自然界各种水体中溶解无机碳(DIC)含量及其稳定碳同位素组成的分析。更多还原

【Abstract】 An analytical method for measuring concentration and carbon isotopic compositions of dissolved inorganic carbon(DIC)in natural water is established by continuous flow-isotope ratio mass spectrometer(CF-IRMS).The instrument used in this study is a Finnigan Delta Plus XP stable isotope mass spectrometer coupled with online sample preparation device(Gas Bench II).In general, 0.5 mL of water samples is taken and reacted with pure H3PO4 in a glass vial, and the produced CO2 is transferred into the mass spectrometer and δ13C values are measured.Four laboratory water standards have been prepared, and their carbon isotopic ratios are determined and the results are of high quality.Additionally, 44CO2 intensity shows a liner correlation with DIC concentration of standard, which indicates that DIC concentrations can also be obtained from the CF-IRMS data.The method gives an analytical precision of 0.1‰for δ13C measurement.This method can be used to analyze δ13C values of DIC in nature water such as river water, lake water, sea water, underground water and pore waters.更多还原