Abstract
A simple and low-cost differential pulse-adsorptive cathodic stripping voltammetry (DP CSV) approach has been established for trace determination and speciation of Pb using Thorin-I as selective chelating agent. The established assay was based upon controlled preconcentration of Pb-Thorin complex at pH 8.3-9.0 at a hanging mercury dropping electrode (HMDE). The resulting cathodic peak current (I-p,I-c) at - 0.56 V was then measured versus Ag/AgCl reference electrode. The plot of I-p,I-c versus Pb concentration under the optimized parameters was linear in the concentration range 3.5 x 10(-10) - 5.0 x 10(-7) mol L-1. The lower limits of detection (LOD) and quantification (LOQ) of Pb were 1.05 x 10(-10) and 3.5 x 10(-10) mol L-1, respectively. The planned assay was satisfactorily applied for total analysis and speciation of Pb in various water and food samples. Validation of the developed probe was successfully achieved by analysis of Pb in certified reference material.