A simple procedure for the determination of platinum group elements and rhenium (Ru, Rh, Pd, Re, Os, Ir and Pt) using ID-ICP-MS with an inexpensive on-line matrix separation in geological and environmental materials

Abstract

A simple and highly selective analytical procedure is presented here for the concentration determination of Ru, Rh, Pd, Re, Os, Ir and Pt via isotope dilution, which is suitable for the investigation of geological and environmental materials. Sample preparation consists of a sample digestion step in a high pressure asher (HPA-S) with concentrated HNO₃ and HCl and drying down of the sample solution after the Os concentration was determined via sparging OsO₄ into an ICP-MS. After drying and redissolution of the remaining solution the other PGEs are separated on-line from their matrix in a simple cation-exchange column that is coupled to a quadrupole ICP-MS. Through this technique it is possible to monitor in every sample the isotopes of the analytes as well as of those elements that cause isobaric interferences or that potentially cause interferences through molecular species. Concentrations of the two or more isotopic elements can be calculated through isotope ratios, whereas Rh is calculated via the peak area. Data for ultramafic reference materials UB-N and GP13 with concentrations lower than 8 ng g⁻¹ show excellent reproducibilities (n = 9) for Re, Pd and Pt (2.5–3.9% RSD) and Pt, Ru, Rh, Os and Ir (4.5–7% RSD). It can be demonstrated that a large portion of the higher standard deviations is caused by sample heterogeneity. Road dust (BCR-723) was included to demonstrate the strength of this procedure for the determination of environmental samples. Reproducibilities (n = 5) for Re, Pt and Os were between 1.2 and 2.3% RSD, 5.2% RSD for Pd and 11% RSD for Rh. Data for Ru and Ir are presented for the first time.