Study of the potential response of solid-state chloride electrodes at low concentration ranges

Ion-selective electrodes based on silver chloride precipitates have been investigated in the low concentration range, by use of a specially designed cell of small volume. Electrode potential measurements and silver determinations in the corresponding solutions by atomic-absorption spectrometry were made. The results prove that the potential response of these ion-selective electrodes in the low concentration ranges is governed by inequality of the ion concentrations in the boundary zone of the test solution contacting the electrode membrane. This is a result of adsorption-desorption processes, a dissolution process followed by recrystallization of the silver chloride at the electrode membrane surface, and photoreduction of silver ions at the electrode surface.