四极质谱计测量天然水平氘氢丰度比

Measurement of Natural Level Ratio of D and H by Quadrupole Mass Spectrometer

自制了高温铬还原制氢装置;探索了降低复合氢离子H3+对氘化氢离子HD+干扰的方法。以氘丰度为天然水平的国家一级标准水样中的两个样品作为标准,另外两个样品作为测试样品,在GAM400四极质谱计上探索了等氢分子离子H2+线性校正测量值的方法。利用双标准外标氘氢丰度比差值校准系数的方法对两个标准水样进行了测量,结果与国家标准值偏差为±0.1%,最终评估测量相对不确定度为0.8%。

A device with high temperature Cr inside is made to reduce water to hydrogen. The method for reducing the interferer of H3^＋ to HD^＋ is discussed. Two samples of a set of national standard water samples which have natural level ratio of D and H are set as standards and the other two as unknown samples, a linear calibration method with equal H2^＋ is studied on GAM400 quadrupole mass spectrometer, the difference calibrated coefficient of the ratio of D and H is obtained between two standards. The other two standard water samples are measured based on the methods and the coefficient. The measured results have ±0.1% bias to national standard values. And the evaluated relative uncertainty is 0.8%.