Ion-selective electrode membrane system based on a vinyl chloride-vinyl alcohol copolymer matrix and its role for accommodating grafted alkyl phosphate sensors

Abstract

Limited amounts of a polymer containing hydroxyl groups (copolymer VAGH) can be incorporated into PVC matrices containing Orion 92–20–02 calcium liquid ion exchanger. Such hydroxyl groups also provide suitable sites for grafting alkyl hydrogen phosphate calcium-ion sensors. Calcium ion-selective electrodes can also be fabricated from membranes containing the grafted sensors. These are of fast and steady response but there are no other noticeable advantages.

Because of the nature of pH interference of calcium ion-selective electrodes based on alkyl phosphate sensors, improved electrode calibration can be obtained by calcium-ion standards in tris buffer at pH approximately 7.5.