Measurement of the isotopic composition and atomic weight of an isotopic reference material of platinum, IRMM-010

Abstract

An isotopic reference material (IRM), IRMM-010, was prepared as a metallic platinum wire and certified for isotopic composition of platinum. The measurements were carried out with a quadrupole inductively coupled plasma mass spectrometer (ICP-MS) in peak jumping mode using a secondary electron multiplier as detector. Five synthetic isotope mixtures with certified isotope amount ratios of n( 196Pt)/ n( 195Pt) were prepared in order to calibrate the measurements. The synthetic isotope mixtures, the natural platinum reference material as well as the isotopically enriched materials were measured in a 2% HNO 3 and 2% H 2O 2 matrix in order to reduce memory effects during the measurements. These measurements resulted in certified isotope amount ratios and isotopic composition of a platinum reference material with natural isotopic composition. The relative abundances of the different platinum isotopes were determined as: 0.0117±0.0012 amount % of 190Pt, 0.782±0.016 amount % of 192Pt, 32.86±0.27 amount % of 194Pt, 33.77+0.16 amount % of 195Pt, 25.21+0.23 amount % of 196Pt, and 7.356±0.087 amount % of 198Pt. This lead to an atomic weight equal to 195.0844±0.0058 for this material. The purity of IRMM-010 was measured, the total impurity was found to be 140±140 μg·g −1. Uncertainties are expanded combined uncertainties expressed with a coverage factor k=2.