Simultaneous measurement of major, trace elements and Pb isotopes in silicate glasses by laser ablation quadrupole and multi-collector inductively coupled plasma mass spectrometry

Abstract

A method was developed for the rapid in situ analysis of major and trace elements and Pb isotopes in silicate glass samples that combines laser ablation quadrupole and multi-collector inductively coupled plasma mass spectrometry (LA-Q-ICP-MS/MC-ICP-MS). Major, trace elements, and Pb isotope ratio compositions were clearly affected by laser conditions. Using a laser spot size of 160 μm, a laser ablation frequency of 15 Hz, an energy density 18 J/cm2, and a 1: 9 ratio of laser ablation aerosol to the corresponding makeup gas, we obtained accurate major and trace element contents and Pb isotope ratios. Using Ca as the internal standard element, and GSE-1G and NIST 610 as the external standards for calibration, element contents generally matched the preferred values within 15%. Higher relative errors for some elements (e.g., Cr, Ga, Ge) may have been caused by lower than recommended values in some standards. The exponential law correction method for Tl normalization, with optimum adjusted Tl ratio, was utilized to obtain Pb isotopic data with good precision and accuracy. Pb isotopic ratios of the glass reference materials were in good agreement with the reference or published values to within 2 s measurement uncertainties, and the analytical precision was better than 0.17% (e.g., 208Pb/206Pb). The developed method is a simple, reliable, and accurate technique for determining major, trace elements, and Pb isotope compositions of silicate glasses and minerals within a single ablation event.