Determination of Rhenium in Geological Samples by Isotope Dilution–Multicollector–Inductively Coupled Plasma-Mass Spectrometry with Novel Chromatographic Separation

Abstract

A method was developed to determine rhenium contents in geological samples using multicollector–inductively coupled plasma-mass spectrometry (MC–ICP-MS) and extraction with an ion-exchange resin. Samples were digested in Carius tubes and osmium was converted into volatile OsO₄, which was purified by distillation and microdistillation. The purified Os contents and isotopic ratios were determined using negative thermal ionization mass spectrometry. After the distillation of Os, the samples were treated with HF, then 1.2 M HCl, and loaded on ion-exchange resin columns. Re was eluted using 0.75 M HNO₃ and directly determined by MC–ICP-MS. This method was validated using a series of reference materials and the analytical Re data are consistent with the literature values. This method precision (relative standard deviation) ranged from 0.8 to 6%. The procedural blank and detection limit (3σ) of Re were 1.1 pg and 0.5 pg/g (for a sample size of 2g), respectively. These results indicate that the proposed method can be applied to determine trace Re in geological samples. Using Carius tube digestion combined with HF desilicification and redissolution, the Re and Os contents found in the soluble and insoluble phases of several reference materials indicated that the distributions of Re and Os were homogeneous and heterogeneous, respectively.