Ion-Selective Electrodes in Biomedical Analysis

I. INTRODUCTION AND SCOPE

The ion-selective electrode is an electrochemical sensor characterized by a selective response to a particular ionic species. The wording “selective” rather than “specific” is considered since it is very rare that an electrode responds to a single ion exclusive of all others. The ion-selective electrode is further described as a membrane sensor which responds in a potentiometric manner. That is, the potential which develops across an ion-selective membrane separating two solutions is measured at virtually zero current. This is a rather unique and intriguing event which has founded an expanding analytical field which has come of age within the last 15 years.