DETERMINATION OF PLATINUM-GROUP ELEMENTS AND GOLD IN GEOLOGICAL-MATERIALS USING AN ULTRAVIOLET-LASER ABLATION HIGH-RESOLUTION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC TECHNIQUE

In this work, a UV laser system coupled to high-resolution ICP-MS was used in the determination of platinum group elements (PGE) and gold in nickel sulfide buttons prepared by the fire assay technique, A Nd:YAG laser operating at 266 nm quadrupled frequency was used. The laser op erating parameters were established by studying signal intensity and t he precision for different energy beams and frequencies. The F-test wa s used to evaluate the homogeneity of the buttons, demonstrating that for most elements the distribution is homogeneous. The analyses were p erformed on three different sites in three replicates of the materials . The detection limits obtained (3 sigma) were in a range from 0.2 for Os (and Ir) to 7 ng g(-1) for Pt. The accuracy of the results was bet ter than 16.7% for most elements. The effects of isobaric interference on the Rh-103 signal (Pb-206(2+) and (ArCu+)-Ar-40-Cu-63) were evalua ted by analysing NiS buttons doped with lead and copper. For Au, Pt an d Pd, the standard deviations obtained were higher than expected and a re related to a non-homogeneous distribution of these elements in the buttons. The concentrations of the elements in the geological referenc e materials UMT-1 and WPR-1 were obtained by external calibration curv es.