Original Articles
Deswati*, Hamzar Suyani, Rahmi
Abstract
A sensitive and selective electrochemical procedure is presented for simultaneous determination of tra ce levels of Cd(II), Cu(II), Pb(II) and Zn(II) in water samples with calcein as a chelating agent. The method is ba sed on the adsorptive accumulation of the complexes of Cd(II), Cu(II), Pb(II) and Zn(II) ions with calcein onto the surface of hanging mercury drop electrode for 60 seconds, Then the preconcentrated metals-complexes were analyze d by adsorptive stripping differential puls voltammetry. The effect of various parameters such as pH, conce ntration of calcein, accumulation potential and accumulation t ime were studied. The optimum conditions for simult aneous determination of Cd(II), Cu(II), Pb(II) and Zn(II) include pH 4.0, calcein concentration of 0.6 mmol/L , accumulation potential of -0,7 V (vs. Ag/AgCl) and accumulation time of 60 seconds. Under the optimum conditions the measurement peak current is proportional to the concentration of Cd(II), Cu(II), Pb(II) and Zn(II) in the range 0.2 - 110 μ g/L ; 0.2 – 100 μg/L ; 0.2 – 110 μ g/L ; and 0.2 – 100 μ g/L respectively. The lim its of detection were 1.38 μ g/L for Cd(II), 0.76 μ g/L for Cu(II), 1.43 μ g/L fo r Pb(II) and 0.98 μ g/L for Zn(II). The relative sta ndard deviation were 0.84%, 0.25%, 0.43% and 0.54% for Cd(II), Cu(I I), Pb(II) and Zn(II) for ten replicates (n = 10) m easurements of mixture solution 10 μ g/L of Cd(II), Cu(II), Pb(I I) and Zn(II). The methods were successfully applie d for simultaneous determination of Cd(II), Cu(II), Pb(II ) and Zn(II) in sea water, tap water and lake water .