Detection of chloride ion concentration using chronopotentiometry

In this paper, a novel approach is reported for the electrochemical measurement of chloride ions using chronopotentiometry. A current pulse is applied at the Ag/AgCl working electrode and the potential change is measured with respect to another identical Ag/AgCl electrode in the bulk electrolyte. The potential difference, given by the Nernst equation, follows an inverse logarithmic trend versus the Cl̅ ion concentrations. The sensitivity of the response is tuneable through the applied current pulse and the corresponding concentration window. The potential response is also influenced by the pH of the electrolyte, this effect is pronounced at low concentration of Cl̅ ions (<; 1 mM KCl) and high pH values (>12 pH). The advantage of this approach is that a bare Ag/AgCl electrode can be used as a pseudo-reference electrode. Additionally tuneable sensitivity is obtained and the dissolution of sparingly soluble AgCl membrane is counteracted. This system can be used for long term application like in-situ measurement of Cl̅ ions in concrete.