REFERENZELEKTRODE

A reference electrode system for a disposable test cell which provides both a reference electrical potential and a liquid junction between the reference medium and an analytic or sample medium to which a sample is introduced to be tested includes a substrate carrying and supporting a thin metallic electrode layer, an hydrophilic medium overlays the electrodes, a portion connecting the metallic layer and the sample conducting medium to provide an electrical connection and free diffusion liquid junction with the sample medium, a liquid impermeable dielectric barrier layer sealing all but a selected, relatively minor portion of the hydrophilic medium exposed to contact the analytic medium. Electrolyte salts introduced into the free diffusion channel control both the reference electrode potential and the junction potential.