A CLAIBRATION TECHNIQUE OF SILVER/SILVER CHLORIDE REFERENCE ELECTRODE BY USING RELATIONSHIP BETWEEN ELECTRICAL CONDUCTIVITY AND KCL CONCENTRATION OF THE INTERNAL ELECTROLYTE

摘要

For ensuring the long-term performance of an Ag/AgCl reference electrode, a correction technique was established by using the linear relationship between the electrical conductivity and KCl concentration of the internal electrolyte. The electrical conductivity of various KCl solutions was measured. At the same time, the potential shifts of the Ag/AgCl electrode with the internal electrolyte of various KCl concentrations were obtained. The electrical conductivities increased with an increase of the KCl concentration, and the potentials of Ag/AgCl electrode shifted anodically with a decrease of KCl concentration. We also examined the interference effect of boric acid on the electrical conductivity and the potential shift of the Ag/AgCl electrode. The conductivity and the potential values were not affected with the addition of the boric acid. For simulating a long-term exposure of electrode, we designed a reference electrode with a timely open hole to accelerate the diffusion of internal electrolyte. The Ag/AgCl electrode filled with 0.1 M KCl was exposed in distilled water and 0.016 M boric acid, respectively. As the results, the electrical conductivities decreased, and the potentials shifted anodically with an increase of the number of dilution. In addition, the concentration changes of the internal electrolyte were evaluated by using the empirical equation between the electrical conductivity and KCl concentration. We also calculated KCl concentration by the relationship between the electrical conductivity and chemical activity of KCl.