Devices for ion-sensing and pX measurements

Abstract

Thirty years of ion-selective electrode (ISE) researches at the University of Wales, Cardiff are outlined. They summarize developments of PVC membrane ISEs, first for calcium and then of other systems, including the improved calcium dioctyl-phenyl-phosphate sensor for calcium and those of ion-exchangers, polyalkoxylates, and cyclic and acyclic polyethers for various anions and cations. Electrodes based on polyalkoxylates have interesting properties toward the polyethers themselves. Some ISE failure causes are discussed. Attention is given to applications, including analysis of wash liquors and nonionic surfactants, biomedical roles, and studies of sulfate-reducing bacteria activity. Coated-wire ISEs and ion-selective field effect transistors (ISFETs) are mentioned, as are other modes of ISE deployment. The review concludes with some fundamental features of PVC electrode membranes as determined by radiotracer, applied potential, and potentiostatic approaches.