The Development Method for a Sensitive Simultaneous Determination of Pb(II), Cd(II) and Zn(II) by Adsorptive Cathodic Stripping Voltammetry Using Alizarin as a Complexing Agent

An adsorptive cathodic stripping voltammetric method is presented for the simultaneous determination of Pb(II), Cd(II) and Zn(II) in tap water with alizarin as a complexing agent. The method is based on adsorptive accumulation of the complexes of Pb(II), Cd(II) and Zn(II) ions with alizarin onto hanging mercury drop electrode (HMDE), followed by the reduction of the adsorbed species by adsorptive cathodic stripping voltammetry (AdCSV). The optimized experimental conditions include: supporting electrolyte (acetate buffer), pH (5), alizarin concentration (0.5 mM), accumulation time (60 s), accumulation potential (-0.2 V). This method has been applied to determine Pb(II), Cd(II) and Zn(II) in tap water. The concentration of metal ion in tap water was obtained Pb(II) 0.045, Cd(II) 20 and Zn(II) 129 mu g/L. the detection limit was Pb(II) 0.008, Cd (II) 0.005 and Zn(II) 0.001 mu g/L, relative standard deviation was obtained Pb(II) 1.2, Cd(II) 0.4 and Zn(II) 1.12% (n=10), recovery was obtained Pb(II) 99.45, Cd(II) 98.66 and Zn(II) 99.72%. The accuracy of the obtained voltammetric analytical results was validated by comparing with that obtained by the atomic absorption spectrometric method, Concentration of the metal ion in tap water was obtained with AAS technique Cd(II) 16 mu g/L, Zn(II) 115 mu g/L and Pb(II) not detected.