THERMODYNAMIC SIMULATION OF THERMOCHEMICAL PROCESSES IN INDUCTIVELY-COUPLED PLASMA

A multicomponent quasi-equilibrium thermodynamic model of thermochemic al processes in inductively coupled plasma is proposed. The electron c oncentrations and degrees of ionization are calculated for more than 7 0 elements using various modeling conditions at temperatures 6000-9000 K. A comparison is made with similar results obtained by the Saha equ ation for a simplified two-component plasma model. Recommendations are made on the ways of increasing the degree of ionization of elements, selecting the internal standard, using negative-ion mass spectra for a nalysis, and thermodynamic simulation with the use of a unified comput ational mode. An equation describing the sensitivity of an inductively coupled plasma mass spectrometer to the detected ion masses is propos ed. With the use of experimental detection limits and calculated parti al pressures of isotope ions, such well-defined sensitivity functions are obtained for industrial instruments of various types produced by v arious firms. This confirms the legitimacy of using the proposed multi component quasi-equilibrium thermodynamic model for studying the analy tical characteristics of inductively coupled plasma.