Cathodic stripping voltammetry of thiosulphate at toxic concentrations Original Research Article

Low concentrations of sodium thiosulphate may be determined by cathodic stripping voltammetry using a miniaturized modified mercury drop electrode, if the accumulation of the analyte is realized at relatively positive potential values (0.15–0.27 V vs. Ag/AgCl (sat. KCl)) and when differential pulse voltammetry is applied as a measurement technique. Detection limit of the determination has the value 1.2×10−8 mol l−1. The described electrocapillary drop time–potential (t–E) test confirmed strong electrosorption of S2O2−3 under the applied voltammetric conditions. The interfering effect of sulphide ions on the voltammetric determination of thiosulphate has been eliminated by the application of anodic potential scan after adsorptive accumulation of the analyte at the potential 0.15 V.