CONDUCTIVE EPOXY-BASED ION-SELECTIVE ELECTRODES

Work since the late 1970s to construct conductive epoxy-based ion-selective electrodes (ISEs) and to study their response characteristics is reviewed. The utilization of conductive epoxy supports for the application of sensor membranes has allowed the construction of both crystalline and PVC membrane all-solid-state electrodes. Electrodes have been made with commercial conductive epoxies and metallic (silver and copper) and graphite powders have been used as additives to impart conductivity to non-conductive commercial epoxies. As the materials of the support are easily mouldable and machinable, in addition to electrodes of conventional shape and size, miniaturized and flow-through electrodes for use in flow-injection analysis have been manufactured. Two alternative designs (tubular and sandwich) have been developed. More recently, work has been focused on the study of the influence of temperature on the response of both crystalline membrane and PVC membrane electrodes. A major purpose of this type of research is to improve the operational characteristics of the electrodes by selection of a suitable epoxy base to obtain an adequate position of the isopotential point in each instance.