Stripping voltammetry of silver ions at polythiophene-modified platinum electrodes

The present work describes the development of a modified platinum electrode for stripping voltammetric determination of silver. The deposition of films based on electropolymerisation of the monomer thiophene was carried out by cycling the potential towards positive values between 0 and 1.6 V.The preconcentration process of silver ions was initiated on the surface of the modified electrode by complexing silver with polythiophene (PTH) when a negative potential (−0.5 V) was applied; then the reduced products was oxidized by means of differential pulse stripping voltammetry and the peak was observed at 0.17 V. Parameters such as pH, supporting electrolyte and number of electropolymerisation cycles were studied. A linear relation between current peak and concentration of Ag(I) was obtained in the range 0.07-1.0 mg L⁻¹. The detection limit for Ag(I) was evaluated to be 0.06 mg L⁻¹. The reproducibility was tested carrying out 11 measurements at different electrodes and the relative standard deviation was 1.5%. The interference of several metals was investigated and showed negligible effect on the electrode response.