Determination of Trace Amount of Lead in Water by Differential Pulse Voltammetry with Chemically Pretreated Glassy Carbon Electrode

Glassy carbon electrode (GCE) was pretreated by anodic oxidation at +1.8 V (vs.SCE) and scanned in the potential range of -0.8 to +1.0 V in acetate buffer solution of pH 4.0.The electrochemical behavior of Pb2+ ion at this pretreated GCE was studied.It was found that Pb2+ ion showed a pair of oxidation peak and reduction peak at the pretreated GCE,with their potentials at -0.57 V and -0.68 V (vs.SCE) respectively.The peak current was raised greatly as compared with the reaction at the bare GCE.Based on these findings,a sensitive method for determination of Pb2+ ion by differential pulse voltammetry was proposed.Linear relationship between values of peak current and concentration of Pb2+ ion was obtained in the range of 3.2×10-7-4.2×10-5mol·L-1,with detection limit (3S/N) of 3.2×10-8mol·L-1.The proposed method was applied to the determination of trace amount of lead in water samples,giving values of recovery and RSD′s (n=6) in ranges of 93.8%-104.7% and 3.1%-4.3%,respectively.