Neutral-Carrier-Based Ion-Selective Microelectrodes Design and Application A Review

Abstract

At present, neutral-carrier-and ion-exchanger-based ion-selective liquid membrane microelectrodes are available for the measurement of H⁺, Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, NH₄⁺ and Cl^-. Fundamental aspects, design features and limitations of microelectrodes are discussed and examples for their application in physiology are given. The most important characteristics are summarized in view of intra-and extracellular physiological measurements. The selectivity coefficients K^Pot_ij with respect to the most common ions are compared to calculated values K^pot_{ij, max} required for measurements in intra-and extracellular samples without significant interference. For intracellular microelectrode studies, these required values are fully met for H⁺, K⁺, Mg²⁺, Ca²⁺ and Cl^-, while in the case of extracellular measurements H⁺, Na⁺, K⁺ and Ca²⁺ can be assayed adequately.