Determination of Lead (II) in Some Vegetable Samples by Electrochemical Methods Using Modified Carbon Electrode

Abstract

 The lead (II) ions were determined in some vegetable samples by electrochemical methods using the modified carbon electrode with PEDOT: PSS. This electrode is characterized by its selectivity and high sensitivity to lead (II) ions, in addition to its low cost and toxicity. The cyclic voltammetry curves were show using the modified carbon electrode with PEDOT: PSS and by applying the optimum experimental conditions, two peaks for lead (II), the first corresponding to the oxidation peak at the potential (-360 ± 10) mV, and the second corresponding to the reduction peak at the potential (-550 ± 10). mV. The values of the oxidation peak current density were linearly proportional to the concentrations of lead (II) ions within a range of (1.0-25) ×10-5 mol.L-1. The lead (II) was deposited on the electrode surface by applying a reduce potential (-650)mV for 30sec, then chronoamperometric measurements were taken by measuring the current density of the lead (II) oxidation when applying a constant potential (-350mV) to complete the oxidation (deposition) for 30sec. The current density values were linearly proportional to the concentrations of lead (II) ions within a range from (1.0-100)×10-  9mol.L-1 (r = 0.999), with a percentage standard deviation not exceeding 4.08%, And the LOD was 0.19×10-9mol.L-1. This method showed high selectivity and sensitivity for determining lead ions in some vegetable samples. The comparison of the results obtained with the results of the analysis with the atomic absorption spectrum gave good accord.