Pseudopolarography of trace metals - Part I. The automatic ASV measurements of reversible electrode reactions

The main advantage of automated computer-controlled pseudopolarographic measurements is the possibility of their practical application to the determination of trace metal speciation. This paper describes the pseudopolarographic characteristics of the reversible electrochemical reactions of dissolved trace metals, such as: lead(II), thallium(I) and bismuth(III), in model electrolytes, at a metal concentrations of about 10(-7) mol l(-1), on a stationary mercury drop electrode (SMDE), using a differential pulse anodic stripping voltammetry (DPASV) technique. There is good agreement between the formal potential determined by the sampled do polarography (10(-4) mol l(-1)) and pseudopolarography (10(-7) mol l(-1)). The half-wave potential of the pseudopolarograms shifts with the accumulation time but remains unaffected by the increase of the metal concentration in the solution, which is in good agreement with the theoretical suppositions. The dependence of the shape of the pseudopolarogram on the method used for the determination of the anodic peak current, is presented. The development and the application of an efficient mathematical treatment of the experimental (pseudo)polarographic data for the determination of the half-wave potential, the transfer coefficient, the rate constant, etc., are presented. (C) 2003 Elsevier Science B.V. All rights reserved.