Determination of Platinum-Group Elements and Re-Os Isotopes using ID-ICP-MS and N-TIMS from a Single Digestion after Two-Stage Column Separation

We report an improved procedure for the determination of the platinum-group elements (PGE) and Re, and Os isotopes from a single sample aliquot by isotope dilution (ID) using inductively coupled plasma-mass spectrometry (ICP-MS) and negative thermal ionisation mass spectrometry (N-TIMS), respectively. A two-stage column method was used to purify PGE-Re from their sample matrix and interfering elements (e.g., Mo, Zr and Hf) after Os had been separated by CCl4 solvent extraction. The first column separation step used cation exchange resin (AG50W-X8) to concentrate PGE-Re and some potential interfering elements (e.g., Mo, Zr and Hf). In the second step, N-benzoyl-N-phenylhydroxylamine (BPHA) extraction resin was used to separate PGE-Re from the remaining interfering elements, which all remained strongly absorbed to the resin. The method was used to determine the PGE and rhenium, and Os isotope ratios in a range of geochemical reference materials (TDB-1, WGB-1, BHVO-2 and UB-N). The obtained results agree well with those previously published. This new method enables PGE-Re abundances and Os isotopic ratios to be determined on the same sample digestion, and circumvents the problems created by sample heterogeneity when comparing PGE and Re-Os isotope data.