Optimization of Analysis Conditions by the Method of Inductively Coupled Plasma Mass Spectrometry with Laser Sampling

Resumo

The effect of laser radiation parameters on the sensitivity and relative sensitivity coefficients of element determination in the analysis of various materials by inductively coupled plasma mass spectrometry in combination with laser ablation is studied. It is found that, when the power density of laser radiation is increased above 2 × 10¹⁰ W/cm² for the samples based on silicate glass, basalt glass, and polymetallic sulfides, the laser ablation mechanism changes from thermal to “phase explosion.” It is shown that the coefficients of relative sensitivity of determination of impurity elements with respect to the matrix elements change by no more than 3–5% when the power density varies in the range of 5 × 10⁹–1.5 × 10¹¹ W/cm². For most impurity elements, the coefficients of the relative sensitivity of determination in different matrices differ by no more than 10–15%, but for a number of elements, a significant difference up to 1.5–2 times is observed. A comparative study of two ablation modes is carried out: when the laser beam is moved along the surface of the sample and during ablation at a “point.” It is shown that the sensitivity of determination of the elements in the first case is 2–3 times higher, while the coefficients of the relative sensitivity of determination are the same for both cases.