Fourth Institute of Oceanography , State Oceanic Administration (SOA) , Beihai 536000 , China.
National Research Council Canada , 1200 Montreal Road , Ottawa , Ontario K1A 0R6 , Canada.
Anal Chem. 2018 Aug 7;90(15):9281-9288. doi: 10.1021/acs.analchem.8b01859. Epub 2018 Jul 16.
Despite its widespread applications in geology, all osmium isotope ratio measurements are either uncalibrated or rely on the veracity of the uncalibrated 1937 Nier values by adopting them as normalizing constants typically in conjunction with an exponential mass bias correction model. In this study, isotope ratios of osmium were determined in six commercial osmium materials, including the DROsS standard and a new NRC isotopic osmium reference material OSIS-1, by MC-ICPMS. We use a previously optimized and validated regression mass bias correction model to correct instrumental isotope fractionation effects which does not rely either on Nier's values or on a strictly mass-dependent behavior of the isotopes. Deviations from mass-dependent fractionation (mass independent fractionation) were observed for osmium isotopes in MC-ICPMS with the most dramatic effect occurring for Os, wherein, on average, close to half-percent bias in the isotope ratio Os/Os was observed as a result of imposing Russell's law.
尽管锇同位素比值测量在地质学中得到了广泛应用，但所有这些测量都没有经过校准，或者依赖于未经校准的 1937 年 Nier 值的准确性，这些值通常被用作归一化常数，同时结合指数质量偏差校正模型。在这项研究中，我们使用 MC-ICPMS 测定了六种商业锇材料（包括 DROsS 标准和新的 NRC 同位素锇参考物质 OSIS-1）中的锇同位素比值。我们使用了先前优化和验证的回归质量偏差校正模型来校正仪器同位素分馏效应，该模型既不依赖于 Nier 的值，也不依赖于同位素的严格质量依赖性行为。在 MC-ICPMS 中，观察到锇同位素存在偏离质量依赖性分馏（质量无关分馏）的现象，其中 Os 的影响最为显著，由于强加了 Russell 定律，Os/Os 同位素比值的平均偏差接近 0.5%。
