National Research Council Canada , 1200 Montreal Road, Ottawa, Ontario K1A 0R6, Canada.
College of Ocean and Earth Sciences, Xiamen University , Xiamen, Fujian 361102, PR China.
Anal Chem. 2017 Sep 5;89(17):9375-9382. doi: 10.1021/acs.analchem.7b02206. Epub 2017 Aug 18.
Like many other elements, iridium is lacking a calibrated, SI traceable isotope ratio measurement. In this study, we have undertaken absolute isotope amount ratio measurements of iridium by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) using a state-of-the-art regression model to correct for the instrumental fractionation (mass bias) of isotope ratios using both NIST SRM 997 isotopic thallium and NIST SRM 989 isotopic rhenium as primary calibrators. The optimized regression mass bias correction model is based on incrementally increasing plasma power and short (10-30 min) measurement sessions. This experimental design allows fast implementation of the regression method which would normally require hours-long measurement sessions when executed under constant plasma power. Measurements of four commercial iridium materials provide a calibrated iridium isotope ratio R = 1.6866(6) which corresponds to isotopic abundance x = 0.372 21(8) and an atomic weight of A(Ir) = 192.217 63(17). In addition, we present data on a new Certified Reference Material from NRC Canada IRIS-1 which fulfills the requirements of a delta zero reference for iridium isotope ratio measurements.
与许多其他元素一样，铱缺乏经过校准的、与 SI 可溯源的同位素比测量。在这项研究中，我们使用最先进的回归模型，通过多接收电感耦合等离子体质谱（MC-ICPMS）对铱进行了绝对同位素丰度比测量，以校正仪器分馏（质量偏差）对同位素比的影响，同时使用 NIST SRM 997 同位素铊和 NIST SRM 989 同位素铼作为主要校准标准。优化的回归质量偏差校正模型基于逐步增加等离子体功率和短（10-30 分钟）测量时间。这种实验设计允许快速实施回归方法，而当在恒定等离子体功率下执行时，该方法通常需要数小时的测量时间。对四种商业铱材料的测量提供了经过校准的铱同位素比 R = 1.6866(6)，对应于同位素丰度 x = 0.372 21(8)和原子量 A(Ir) = 192.217 63(17)。此外，我们还提供了来自加拿大 NRC 的新认证参考物质 IRIS-1 的数据，该物质满足铱同位素比测量的零 delta 参考要求。
