METAL-OXIDE METAL PH SENSOR - EFFECT OF ANIONS ON PH MEASUREMENTS

The electrochemical growth of iridium oxide on iridium (IrOx/Ir) elect rodes for use as pH sensors was examined. Usefulness of the electrodes was evaluated in a variety of solutions with anions of various oxy-su lfur species. IrOx/Ir electrodes were prepared, calibrated, and tested in sulfate-, sulfite-, bisulfite-, and thiosulfate-containing solutio ns of various concentrations. There were no serious effects of sulfate and sulfite ions on pH measurements by IrOx/Ir electrodes. After expo sure to solutions with bisulfite and thiosulfate ions, considerable ch anges in calibration of the electrodes were observed, however.