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

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(Pt-196)/n(Pt-195) 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% HNO3 and 2% H2O2 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 Pt-190, 0.782 +/- 0.016 amount % of Pt-192, 32.86 +/- 0.27 amount % of Pt-194, 33.77 +/- 0.16 amount % of Pt-195, 25.21 + 0.23 amount % of Pt-196, and 7.356 +/- 0.087 amount % of Pt-198. 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 mug.g(-1). Uncertainties are expanded combined uncertainties expressed with a coverage factor k = 2. (C) 2002 Elsevier Science B.V. All rights reserved.