利用FinniganMAT-252气体同位素质谱计分析碳酸盐氧同位素的结果校正

利用FinniganMAT-252气体同位素质谱计在进行C、O同位素的分析测试过程中,如果待测样品反应过程中的同位素分馏(α2)与工作气体标定反应过程中同位素分馏(α1)不相等,则气体同位素质谱计系统输出结果与样品实际同位素值之间存在偏差。本文提出了一种校正方法校正这种偏差,公式为:真实值=系统输出值+103ln(α1/α2)。对标准物质在不同条件下进行分析测试,再利用此方法进行校正,得到的校正值与标准物质的真实值之间的误差在±0.2‰之内。

Oxygen Isotope Calibration of Carbonate Minerals Measured by Finnigan MAT-252 Gas Mass Spectrometer

Finnigan MAT 252 gas mass spectrometer has been used for oxygen and carbon isotope analysis, however, during the process of oxygen isotope analysis of carbonate minerals, the output results directly from the mass spectrometer would have a difference from the real δ 18 O value of carbonate minerals if the fraction( α 1) in the process of defining the isotope value of work gas is unequal to the fraction( α 2) during analyzing sample. In this paper we suggest a formulation to overcome the difference : δ x= δ 1+10 3ln( α 1/ α 2). After calibrated by the formulation, output results are compatible with the real value within error(±0.2‰) .