Bandinio sudėties įtakos elementų koncentracijų nustatymui indukcinės plazmos masių spektrometrijoje tyrimas

Abstract

Measurements of the signals proportional to the radiation intensities or the number densities of the charged particles in argon ICP plasma are between the most popular methods of analysis of low concentrations of elements. But the relationships between the signals and the quantity of element in the sample are very complicated, depend on many physical phenomena and chemical reactions and must be calibrated by application of the reference materials. The accuracy of analysis depends on the level of agreement between the compositions of the RM matrices and the sample. As the exact matching is not possible the signal formation in the argon plasma and the effects of matrices on the analytical results should be studied. A method of calibration of the dependence of the sensitivity of the mass spectrometer on the ion masses and methods to determine the electron density and temperature from the mass spectrometric measurement data were proposed. Those aid estimation of the ion signals for analysis and assessment of the measurement uncertainty. The largest matrix effects usually are due to easy to ionize elements. The results show that those elements in argon plasma, depending on the ionization potentials and the structure of the atomic energy levels, differ in possibilities to increase the temperature, the temperature and density gradients, deviation from the local thermodynamic equilibrium, take part in charge transfer reaction between doubly ionized ions and argon atoms. The phenomena are important in the ionization balance in argon plasma.The accuracy of the method of additions with the appropriate internal standard is shown to be comparable to the accuracy of the method of the isotope dilution, and a criterion to test the level of freedom of the method of additions from the matrix effects was proposed