ADSORPTIVE STRIPPING SQUARE-WAVE VOLTAMMETRY OF BI(III) IN CHLORIDE MEDIA - INFLUENCE OF TRITON X-100

Chloride induced adsorption of bismuth(III) ions in submicromolar conc entrations is analysed by square-wave voltammetry in the cathodic stri pping mode. The application of this method for the qualitative metal s peciation at interfaces is demonstrated. By the separation of diffusiv e and adsorptive current components, the adsorption constant of the su rface active complex BiCl4- is estimated as beta4GAMMMA(BiCl4,max) alm ost-equal-to 8 x 10(-3) cm. The lowest concentration of Bi(III) ions d etectable by adsorptive stripping square-wave voltammetry is 10(-7). U nder the influence of Triton X-100, the neutral complex BiCl3 is adsor bed predominantly at a mercury electrode surface, instead of BiCl4-. T his suggests that the variation of the potential of zero charge may ca use a change of the charge of surface active species, i.e. the number of ligand ions in the complex which adsorbs at a certain potential dep ends on the charge of the electrode surface.