Cathodic stripping voltammetry of thiosulphate at toxic concentrations

Low concentrations of sodium thiosulphate may be determined by cathodic str ipping voltammetry using a miniaturized modified mercury drop electrode, if the accumulation of the analyte is realized at relatively positive potenti al 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 d etermination has the value 1.2 x 10(-8) mol l(-1). The described electrocap illary drop time-potential (t-E) test confirmed strong electrosorption of S 2O32- under the applied voltammetric conditions. The interfering effect of sulphide ions on the voltammetric determination of thiosulphate has been el iminated by the application of anodic potential scan after adsorptive accum ulation of the analyte at the potential 0.15 V. (C) 1999 Elsevier Science B .V. All rights reserved.