Evaluation of the Ferric Ion Sensitive Chalcogenide Glass Electrode

Further information is presented on the preparation, composition, performance, and ferric ion sensing mechanism of the chalcogenide glass . Properly prepared and activated electrodes respond to changes in ferric ion concentration in perchlorate, chloride, and nitrate solutions with an average Nernstian slope of , over the concentration range of ferric iron (based on 16 electrodes). Useful response is found down to at least . Details are presented on the activation and operating procedures. Although a complete evaluation of the sensing mechanism has not been made, it has been established that the activation process involves both an oxidation of the fresh surface as well as a chemical interaction of this surface with ferric iron from solution. The sensing process then involves exchange of ferric iron with this modified surface.