A possible steady state kinetic model for the atomization process during flame atomic spectrometry: Application to mutual atomization interference effects between group I elements

Abstract

A possible steady state kinetic model for the atomization process during flame atomic spectrometry is presented. It takes into account the relative rates of (a) thermal dissociation of analyte and interferant metal salts, (b) recombination of counter atom and analyte and interferant atoms, (c) charge transfer between analyte and interferant species, and (d) ion/electron collisional de-ionization. The model predicts a law of mass action type of the thermal dissociation constant in agreement with the currently accepted p-LTE theory. Expressions are derived for the analyte ground state population in the absence and presence of an interferant metal in terms of the rate constants for thermal dissociation of analyte and interferant salts, recombination of counter atom and analyte and interferant atoms, charge transfer between analyte atoms and interferant metal ions and collisional de-ionization, and α and β, the fractions of analyte ions undergoing charge transfer and collisional de-ionization, respectively. The estimation of α and β, and of the various rate constants is discussed. Data are presented showing that the predictions of the model are consistent with the observed interference effects.