Theoretical description of the ligand function for ionoselective electrodes reversible to metal anion complexes. 3. Modeling of the electrode response in ligand and foreign ions solutions using the multi-species approach model

A description for the ligand function of tetrathiocyanatozincate selective electrode, has been proposed, using a multi-species approach model. This model takes into account simultaneous phase-boundary, diffusion-controlled, processes ion exchange between tetrathiocyanatozincate, thyocyanate and foreign ions unable to form zinc complexes, as well distribution neutral complex phases, partial decomposition quaternary ammonium salt stepwise formation in water phase. The is based on solving system equations describing several interphase intraphase equilibria, assuming that diffusion flows all membrane solution components at phase boundary are stationary. It provides adequate electrode solutions ligand, mixed above, predicts effect chloride concentration sample upon slopes, lower detection limits selectivity coefficients.