Simultaneous determination of lead and copper by carbon paste electrode modified with pyruvaldehyde bis(N,N '-dibutyl thiosemicarbazone)

A carbon paste electrode modified with a new chelating reagent pyruvaldehyd e bis(N,N'-dibutyl thiosemicarbazone) (TPSB) for the voltammetric simultane ous determination of lead (II) and copper (II) was described by anodic stri pping voltammetry (ASV). The metal ion is accumulated on the surface of the modified electrode by the chelating effect of the modifier in the carbon p aste, and then is determined by ASV after the potential reduction at-1.0V. For a 5-min accumulation time, two linear calibration graphs were obtained in the range 2x10(-6) to 8x10(-8) M and 1.57x10(-7) to 1.26x10(-9) M for le ad and copper, respectively. The detection limits are 2x10(-9) M for lead a nd 1.57x10(-10) M for copper for 20 minutes of accumulation time. A chemica l and electrochemical renewal allows the use of a single modified electrode in multiple analytical determination over several days. For twenty preconc entration-determination-renewal cycles, the peak current of voltammetry of analyte decreases slightly. Many other ions have no or little effect on the determination The mechanism of electrode reaction was also discussed.