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.

A Comprehensive Method for Precise Determination of Re, Os, Ir, Ru, Pt, Pd Concentrations and Os Isotopic Compositions in Geological Samples

“…We tested 8% m/v CrO 3 in 6 mol l −1 H 2 SO 4 +HClO 4 (Becker et al . , Becker and Walker ), 8% m/v CrO 3 in 6 mol l −1 H 2 SO 4 +H 3 PO 4 (Ly and Hidaka ) and only 8% m/v CrO 3 in 6 mol l −1 H 2 SO 4 as oxidants for Ru microdistillation and concluded that 8% m/v CrO 3 in 6 mol l −1 H 2 SO 4 (50 μl)+H 3 PO 4 (25 μl) gave the highest Ru recovery. Consequently, this was used as the oxidant for Ru microdistillation.…”

“…Two kinds of protocol were used for further purification of Re‐Ru in this study (Figure , Table ): (a) 0.25 ml anion exchange column separation of Re and Ru and (b) microdistillation of Ru (Becker et al . , Becker and Walker , Ly and Hidaka ), followed by 0.25 ml anion exchange column separation of Re from the microdistillation residue.…”

“…) and was modified from Becker et al . (), Becker and Walker () and Ly and Hidaka (). The Re‐Ru fraction collected from the 2‐ml anion exchange column was evaporated to a volume of about 50 μl, then transferred to the centre of the cap of a 5‐ml conical Savillex (Eden Prairie, MN, USA) PFA beaker and evaporated to complete dryness.…”

“…Subsequently, a modified 0.25 ml anion exchange procedure was established to further purify the Re‐Ru fraction; especially, for some low Ru samples, the Ru was separated from Re‐Ru fraction by a microdistillation method first (Becker et al . , Becker and Walker , Ly and Hidaka ), followed by small anion exchange separation of Re. More importantly, an Eichrom‐LN separation procedure was established to completely remove residual Zr and Hf in the Pd and Ir‐Pt fractions, respectively, such that the ZrO interferences on Pd and HfO interferences on Ir and Pt during mass spectrometric measurements were completely eliminated.…”

Geochemical evidence of the doubleβdecay ofMo100

“…The sample volume was reduced to a small drop and microdis-tilled, using a K 2 Cr 2 O 7 -HClO 4 mixture as the oxidizing agent and HCl as the reducing agent, to further reduce the Mo concentration. The procedural blank, including sample dissolution and distillation, was determined to be 4 ± 2 pg via isotope dilution mass spectrometry (IDMS) [14].…”