Improvement of analytical parameters of ISEs based on phosphoryl-containing podands

Dependence of analytical characteristics of ion-selective electrodes (ISEs) based on ionophores with phosphoryl-containing podands on concentration of the lipophilic anionic compounds (sodium tetraphenylborate or potassium te trakis-p-Cl-phenylborate) and on lipophilic properties of these additives a re investigated. It was demonstrated that incorporation of a substoichiomet ric amount of the lipophilic anionic compounds leads to an abrupt increase in selectivity of the Ca- or/and Ba-selective electrodes over the alkali me tals (AMS) and alkaline- earth metals (AEMs) and to a significant improveme nt in the detection limits (DLs) of the ISEs. In case of AMs the changes in the selectivity is larger than for AEMs. The influence of more lipophilic compounds on the potentiometric selectivity and on the DL of the ISE was in vestigated. The qualitative proposed model describing the effect of the nat ure and content of the lipophilic anionic compound in the membrane composit ion on change of the analytical parameters of the ISE: based on phosphoryl- containing ionophores is proposed.