Differential Pulse Anodic Stripping Voltammetric Determination of Lead(II) withN-p-Chlorophenylcinnamo-hydroxamic Acid Modified Carbon Paste Electrode

Abstract

A sensitive and selective method for the determination of lead(II) with N-p-chlorophenylcinnamohydroxamic acid modified carbon paste electrode has been developed. The lead(II) is accumulated on the electrode surface by the formation of the complex in an open circuit, and the resulting surface is characterized by medium exchange, electrochemical reduction, and differential pulse anodic stripping voltammetry. The electrochemical response was evaluated with respect to carbon paste composition, pH and concentration of accumulating and stripping solutions, preconcentration time, lead(II) concentration, and other variables. Two linear ranges were obtained in the concentration ranges 1.00×10–6–2.40×10–5 M Pb(II) with 2 min preconcentration time and 2.00×10–8–1.00×10–6 M Pb(II) with 6 min preconcentration time. The detection limit was found to be 1.00×10–8 M with 6 min preconcentration time. For six preconcentration/determination/renewal cycles, the differential pulse voltammetric response was reproduced with 5.3 % and 4.9 % relative standard deviations at 4×10–6 M and 8×10–8 M Pb(II), respectively. Rapid and convenient renewal allows the use of a single modified electrode surface in multiple analytical determinations over several weeks. Many coexisting metal ions had little or no effect on the determination of lead(II). The developed method was applied to lead determination in potable water.