ABSTRACT
The origins of the development of the successful commercial calcium and nitrate ion-responsive liquid ion-exchanger electrodes can be found in the pioneer work of Sollner and Shean and of Bonner and Lunney with long aliphatic chain quaternary ammonium salts as liquid anion exchange materials and with solvent extraction studies of cations. The simplest form of a liquid ion-exchange ion-selective electrode construction is a U-tube assembly. The capillary of the U-tube is first filled with the exchanger by means of a syringe. Filling of the side arms with internai and external aqueous solutions has to be done with care, by simultaneous syringe injection at identical rates; otherwise expulsion of the exchanger from the capillary occurs. It is experimentally more convenient to utilize a thin, porous, polymeric matrix to support the liquid ion exchanger. The liquid ion-exchanger reservoir is filled by injection from a syringe.
