锌同位素丰度比测量中的几个关键问题

采用多接收-电感耦合等离子体质谱仪(MC-ICP-MS)和多接收-热电离同位素质谱仪(MS-TIMS)对溶液中锌同位素丰度比测量结果进行实验室间比对,5个样品68Zn与66Zn的丰度比为0.02~15.00。比对结果显示,5个实验室的测量结果相符性较差,测量不确定度为1.29%~0.03%(以64Zn/66Zn为例),呈现与样品丰度比相关的趋势,相同仪器测量结果的不相符性主要受是否扣除空白及扣除的准确性影响。另外,MC-ICP-MS系统误差校正条件也影响测量的准确性,MC-ICP-MS质量歧视校正系数为非线性。

Discussion on the Key Factors of Abundance Ratios About Zn Isotope Measurement

The application of Zn isotope analysis is well known in geochemistry and diet study. An inter-lab comparison of five samples with isotopic ratio covering from 0.02 to 15.00 was organized in order to develop measurement ability and keep consistency of the re sults of isotopic ratios measurement among the participants. Multi-collector inductively coupled plasma mass spectrometry （MC-ICP-MS） and multi-collector thermal ionization mass spectrometry （MC-TIMS） were used. For MC-ICP-MS, blank-corrected and blank-no corrected results were submitted. For MC-TIMS, total evaporation method （TE） was applied to the samples while a certified reference material IRMM3702 was analyzed together. All the results showed that the uncertainties were 1.29%-0.03% for G4Zn/6GZn, and the uncertainty was obviously relative to isotopic abundances. The blank-corrected and blank-no corrected and the influence of blank and non-linear of K factor of mass discrimination for MCICP-MS were convinced of contributing to the unsatisfied uncertainties.