H-Selective Electrodes Based on Amine-Type Ionophores: Generalized Theory and A Priori Quantification of Lower and Upper Detection Limits.

A critical analysis of the known theories of functioning of H-selective electrodes (H-SEs) based on neutral amine-type carriers is given. A model of specific ion association is proposed, according to which, in membranes plasticized with 2-nitrophenyloctyl ether, the protonated ionophore and cation-exchanger form much stronger ion pairs with inorganic ions extracted from the sample solution than with each other, and simple equations that describe the lower and upper limit detection (pH and pH) are obtained. A feasible and reliable method for quantifying the p values of ionophores in the membrane phase from potentiometric data is substantiated.

A feasible, fast and reliable method for estimating ion-site association constants in plasticized PVC ion-selective electrode membranes.

A feasible, fast and reliable method for estimating ion association constants in PVC plasticized membranes of ion-selective electrodes from potentiometric data has been theoretically and experimentally substantiated. The method is based on the established fact of complete dissociation of salts of quaternary ammonium cations RN  An (except for those containing methyl substituents at the nitrogen atom) in a membrane plasticized with o-nitrophenyl octyl ether (o-NPOE). Therefore, the boundary potential at the interface of the membrane with an aqueous solution of RN depends only upon the concentrations of the corresponding solution and the ion exchanger in the membrane and is independent of the presence of a lipophilic ionic additive (LIA), which makes it possible to use such ions as reference ones in the internal filling solution.

Strong Bases Design: Predicted Limits of Basicity.

Brønsted superbases have wide applications in organic chemistry due to their ability to activate C-H bonds. The strongest neutral bases to date are substituted aminophosphazenes developed in the late 1980s by Reinhard Schwesinger. Since then, much effort has been expended to create even stronger neutral bases.