Highly selective sulfate PVC-membrane electrode based on 2,5-diphenyl-1,2,4,5-tetraaza-bicyclo[2.2.1]heptane as a neutral carrier

A sulfate-selective PVC-membrane sensor based on 2,5-diphenyl-1,2,4,5-tetraaza-bicyclo[2.2.1]heptane as a neutral carrier is presented. The potentiometric behavior of the electrode is closely dependent on the pH values in test solutions. The electrode revealed a linear response towards SO42− ion in the range of 9.0×10−6 to 1.0×10−1 M with a slope of 28.8±0.2 mV per decade at a pH of 4 (phosphate buffer). The electrode possesses a satisfactory reproducibility, a fast response time, a low limit of detection and, especially, an excellent discriminating ability for SO42− ion with respect to many inorganic and organic anions. The electrode was used as an indicator electrode in potentiometric titration of sulfate and barium ions and in determination of zinc in zinc sulfate tablets.