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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。
The method of measuring dissolved inorganic carbon and carbon isotope composition in water sample was studied by continuous flow isotope mass spectrometry. Four laboratory standards prepared in the laboratory were tested using the DeltaPlusXP isotope mass spectrometer from Finnigan, Germany and the GasBench II on-line sample preparation device Reaction time, equilibrium time, signal intensity, data accuracy and standard stability. The results showed that the detection signal was stable when the equilibrium time was more than 4 h, and the signal intensity of 44 CO 2 was found to be highly correlated with the concentration of dissolved inorganic carbon (DIC) in water samples Therefore, the signal intensity can be used to calculate the concentration of DIC in the original sample. Among the four laboratory standards, the standard configured by NaHCO3 has very good stability and precision as a working standard for testing. The method for measuring δ13C of dissolved inorganic carbon in water sample is 0.1 ‰. The method can be widely applied to the analysis of dissolved carbon (DIC) and its stable carbon isotope composition in various kinds of water in nature.