Determination of ruthenium contents in terrestrial minerals by isotope dilution mass spectrometry after preconcentration via distillation

Abstract

Through the use of acid digestion and a modified distillation procedure the Ru contents in various terrestrial minerals have been determined via the stable isotope dilution mass spectrometry (IDMS) method, with isotopic analysis carried out via inductively coupled plasma mass spectrometry (ICP-MS) and negative thermal ionization mass spectrometry (N-TIMS). The uncertainties in the concentrations ranged from 2.1% to 6.0% (2σ) for ppb and ppm samples concentrations, which is comparable and in some cases better than previous work using NiS fire assay and ICP-MS (Shirai et al., 2003). However, uncertainties for ppt samples were in around 20%, due to low count rates during analysis. Results from three different mineral species show the effectiveness of this chemical dissolution and separation procedure for samples of varying Ru concentrations, ranging from ppm down to ppt levels, and varying geological matrices, from sulphides to silicates. Ru abundances measured showed results consistent with the siderophile nature of Ru, and reinforces the similarity in melt chemistry between Ru and Os. Copyright © 2004 by The Geochemical Society of Japan.