A Review on Sample Preparation in Re-Os Isotopic Analysis

Recent advances in sample digestion and preconcentration used for rhenium and osmium isotope analysis in geological samples were reviewed, including the techniques of nickel sulfide fire assay, alkaline fusion, Carius tube acid treatment and high temperature-high pressure asher decomposion method (HPA-S) for sample treatment. It summarized that the cation or anion exchange chromatography and solvent extraction technologies for separation and concentration of Re, and conventional distillation, micro-distillation, in situ distillation and solvent extraction technologies for separation and concentration of Os. Due to the complexity of geological samples, the heterogencity of Re and Os, different decomposition methods and separation technologies should be considered in specific analyses. It also summaried our experience of sample decomposition and preconcentration for Re and Os in geological samples. At present, the most acceptable method to separate Re and Os is to dissolve the samples with reverse aqua regia in Carius tube, followed by in situ distillation or carbon tetrachloride extraction to separate Os, and finally separation of Re with anion exchange chromatography or acetone extraction.