The noble metal industry requires higher precision and accuracy in material characterization than many other industries. Typically, platinum is determined by fire assay when the platinum content is less than 99%. However, this method is not accurate for analysis of high purity precious materials. Atomic spectrometry with its multi-element capability, high sensitivity, low limits of detection, and fast operation is one of the preferred options for assay of fine precious metals. Atomic emission and mass spectrometry enable accurate determination of impurities present in the sample at the parts per million and parts per billion levels, respectively. The concentration values of the determined impurities are summed and then subtracted from 100% to yield the purity of the platinum sample. In this paper authors discuss the benefits of direct solids analysis using a spark and a laser for the vaporization of platinum samples. Reference materials matching the samples in physical and chemical characteristics were manufactured and certified for the calibration of spectrometers. Those contain nineteen elements, recommended by American Society for Testing and Materials at various concentrations. Both methods are characterized by high sample throughput, good precision, and low detection limits.

Authors: Valentina V. Kogan, Michael W. Hinds