Influence of lipophilic anionic compounds on the selectivity of ion-selective electrodes based on podands with phosphoryl complexing groups

The dependence of the potentiometric selectivity of ion-selective electrode s (ISEs) based on phosphoryl-containing podands on concentration of the lip ophilic compounds (sodium tetraphenylborate or potassium tetrakis-p-Cl-phen ylborate) was investigated, It was demonstrated that the selectivity of the Ca- or/and Ba-selective electrodes over the alkali metals (AMs) and alkali ne-earth metals (AEMs) increases with the lipophilic compound content. In c ase of AMs the changes of the selectivity is larger than for AEMs, It was s hown that employment of the more lipophilic compound, namely, the potassium tetrakis-p-Cl-phenylborate, leads to the greater selectivity growth than f or the sodium tetraphenylborate, A qualitative model which describes the po tential-formation mechanism at the introduction of the lipophilic compounds in membrane composition was proposed. (C) 1999 Elsevier Science B.V. All r ights reserved.