Application of second harmonic alternating current anodic stripping voltammetry in the simultaneous trace and ultra trace metal determination of a multicomponent system

Second harmonic alternating current voltammetry coupled with anodic stripping techniques has been used for the simultaneous determination of lead(II), tin(II), and thallium(I) (elements which, in common supporting electrolytes exhibit similar half-wave potentials). The supporting electrolyte was 0.1 M HClO4 for the Pb-Tl couple with the subsequent addition of EDTA (0.02 M) for measuring the tin ion. Once conditions for the experimental measurements were optimized, calculation was done for the various concentration ratios for which one could determine one element in the presence of the other two; the maximum experimental error was 5%. These concentration (c) ratios were as follows: CSn : CPb = 43:1; CSn : CTl = 32:1 (HClO40.1 M)and CTl:CSn = 45:1; Ctl:CPb = 156:1 (HClO4 0.1 M plus EDTA 0.02 M). Precision and accuracy data (3–5%) are also reported and expressed, respectively, as the relative standard deviation and relative error. The detection limit for each element proved to be around 10−8 M. The standard addition technique improved the resolution of the alteranting current voltammetric method, even in the case of very high concentration ratios.