Potential Correction Technique for Ag/AgCl Reference Electrode Using UV/VIS Absorbance of Internal Electrolyte

Abstract

To improve the long-term performance of Ag/AgCl electrodes, which are commonly used as reference electrodes, a correction technique was developed that involves monitoring the dilution of the internal electrolyte. The dilution of the internal electrolyte was estimated using the UV/VIS absorbance of the electrolyte to which a spectrally active material (a triphenylmethane dye; TPMe) had been added. With this technique, the long-term performance of the Ag/AgCl electrode was investigated when the electrode was exposed to NaHCO 3 solutions with various concentrations. We investigated effects of KCl and NaHCO 3 on the UV/VIS absorbance of TPMe and the effects of TPMe and NaHCO 3 on the potential of the Ag/AgCl electrode. Based on the experimental results, this technique was estimated to be applicable to the correction of the potential of Ag/AgCl electrodes as long as the KCl concentration of the internal electrolyte is maintained between 0.01 and 0.1 M. In NaHCO 3 solutions, the correction technique was found to have another limitation determined by the contamination ratio defined as [NaHCO 3 ]/[KCl].