Liquid/Liquid Interfaces, Electrochemistry at

Abstract This article outlines the electrochemical methodology at the interface between two electrolyte solutions (ITIES). The fundamental concepts of the thermodynamics in biphasic systems are presented in order to show how ions are distributed between the two adjacent phases, and hence how a Galvani potential difference is established at an ITIES. Polarizable and nonpolarizable ITIES are then characterized, and it is further evidenced that the classical electroanalytical methodology at a solid electrode can be directly transposed to the ITIES, thereby allowing reversible charge‐transfer reactions to be easily monitored and interpreted. This theoretical approach is completed by a review of the analytical methods used at ITIES, namely cyclic voltammetry, dropping electrolyte electrodes, optical techniques and microinterfaces (which are the biphasic analogs of microelectrodes). The last part deals with the practical applications that electrochemistry at ITIES has attracted during the last decade in the development of amperometric ion sensors and detectors, in the extraction of metal ions by interfacial formation of a complex and in the assessment of the lipophilicity of ionizable drugs.