Optimization of Conditions of Laser Sampling and ICP-MS Analysis

Abstract

The influence of laser radiation parameters on the sensitivity coefficients of relative sensitivity of element determination in analysis of different materials using ICP-MS method combined with laser ablation is studied. The mechanism of laser ablation is shown to change from thermal to “phase explosion” in the samples of silicon glass, basalt glass and polymetal sulfide as the laser power density increases above 2 X 10¹⁰ W/cm². Coefficients of the relative sensitivity of trace elements determination against matrix elements are shown to change by 3 - 5% when the laser power density varies within the range of 5 x 10⁹ - 1.5 x 10¹¹ W/cm². For most of the trace elements the coefficients of relative sensitivity of their determination in different matrices thus considered differ by 10 - 15 %, however, for some elements the observed difference is rather large being 1.5-2 times and more. A comparative study of two modes of ablation [(i) laser beam scanning along the sample surface and (ii) ablation “in the point”] demonstrated that the sensitivity of element determination is 2 - 3 times higher for the first mode, whereas the coefficients of relative sensitivity of determination being equal for both modes.