Precise determination of the platinum-group elements and Os isotopic ratios in low-level rock samples.
岩石样品中低含量铂族元素和锇同位素比值的高精度测量方法

The platinum group elements (Os, Ir, Pt, Ru, Rh, and Pd) are highly siderophile and chalcophile elements, which are compatible elements and show similar geochemical behaviours. This group of elements includes two radiogenic isotope decay systems of 190 Pt 186 Os and 187 Re 187 Os. Recently, the application of PGEs and Re Os isotope systems in the study of various geological processes, especially in mantle rocks study, has achieved great success and proven to be a useful geochemical tool. Due to the general low concentrations of the PGEs in mantle rocks, it is crucial to develop an analytical method with high precision and high sensitivity. Previous analytical methods such as conventional ICP MS and INAA usually give low analytical precision of >15 to 100% for sub ppb to ppt level rock samples. In addition, the analyses of PGEs and Os isotopic compositions are completed separately using different chemical separation schemes. In this paper, we report a new method that can obtain high precision results for both the PGEs concentrations and the Os isotopic compositions in one aliquot of low level mantle rock samples, using a new sample digestion apparatus (HPA S) and a modified chemical separation method with solvent extraction and anion exchange resins. The PGEs concentrations and Os isotopic ratios of a set of mantle peridotites are measured by MC ICPMS and N TIMS, respectively, and their geological significances are briefly discussed.