Determination of trace levels of Pb(II) in tap water by anodic stripping voltammetry with boron-doped diamond electrode

摘要

A simple and rapid method to determine traces of lead in the Hatyai city tap water by square wave anodic stripping voltammetry with boron-doped diamond (BDD) electrode has been studied. The parameters in the preconcentration steps studied included electrolyte influences, pH, concentrations, and volumes. Effective preconcentration of trace lead was achieved at pH 1.26. The appropriate electrolyte was found to be 0.2 M potassium nitrate (KNO _3) in 0.05 M nitric acid (HNO_3) to make all lead ionic. By scanning potential in the negative direction, the stripping peak was obtained at - 0.460 V. Instrumental parameters including deposition potential, deposition time, scan rate, modulation amplitude, and equilibration time were optimized. The detection limit was found to be 0.3 μg/l. The accuracy was verified by analysing the standard reference material. Several interfering ions were studied and it was found that the method was not significantly affected by these coexisting ions and can be applied satisfactorily to lead determination in water samples. The results from determination of Pb~(2+) using the studied method and ICP-OES were compared and found to be in good agreement. The concentrations of lead in various water samples from eleven regions in Hatyai city were found to be in the range of 0.0-0.8 μg/l, lower than the drinking water contamination standard (< 10.0 μg/l) issued by the World Health Organization.