COMPARISON OF CALIBRATION TECHNIQUES OF AG/AGCL ELECTRODE BETWEEN THE ELECTRICAL CONDUCTIVITY AND THE SPECTRAL ACTIVE TECHNIQUES

摘要

Two creative techniques were developed to correct the potential of an Ag/AgCl reference electrode for ensuring the long-term performance in very dilute solutions. For the electrode correction, we used the changes of the electrical conductivity and the UV/VIS absorbance of the internal electrolyte, respectively. The electrical conductivity increased linearly with an increase of the KC1 concentration, with a logarithmic scale. The UV/VIS absorbance of the KC1 solution added with triphenylmethane (TPMe) was observed to be quite linear with an increase in the TPMe concentration. The potential shift decreased linearly with an increase in the KC1 concentration, with a logarithmic scale. From these results, two different linear relationships were obtained. The first relationship was between the electrical conductivity of the internal electrolyte and the potential shift of the Ag/AgCl electrode. The second was a relationship between the UV/VIS absorbance of the internal electrolyte and the potential shift. For simulating a long-term exposure of the electrode, an Ag/AgCl electrode was treated with a tiny perforation as a junction. During the dilution of the internal electrolyte of the Ag/AgCl electrode, the diluted concentration of the internal electrolyte was estimated by using the electrical conductivity and the UV/VIS absorbance, respectively. In view of the good agreement between the estimated and measured potential values, the feasibility of the suggested calibration techniques was confirmed.