Quantitative determination of gold and the platinum-group elements in geological samples using improved NiS fire-assay and tellurium coprecipitation with inductively coupled plasma-mass spectrometry (ICP-MS)

New fire-assay and tellurium coprecipitation methods were developed for precise determination of Ru, Rh, Pd, Ir, Pt, and Au in geological samples by using ICP-MS. High recovery (>97%) of those elements was obtained by technical improvements including (1) duplicate sample fusion under reduced conditions, and (2) duplicate Te-coprecipitation at an adequate temperature (210°C) and for adequate duration (75 min). Total blanks were less than 1 ng except for Ru and Au, and detection limits were within 2–53 ppt on the rock sample base for all elements. The present procedures are relatively simple and can be applied with high precision and reproducibility to the analysis of geological samples with wide ranges of concentrations.