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.