ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 49, Number 4
JKCSEZ 49(4)
August 20, 2005 

Chemically modified electrodes (CMEs) for determining trace amounts of lead (II) with high selectivity and sensitivity is proposed. The electrodes were fabricated by coating nafion-diethylenetriamine pentaacetic acid (DTPA)-glycerol mixture solution onto glassy carbon electrode surface. Lead (II) ions were accumulated on the electrode surface by the formation of the complex with the ligand at open circuit, and then the resulting surface was characterized by medium exchange, potential reduction, and differential pulse voltammetry. Electrochemical parameters and experimental conditions such as the modifier composition, the amount of modifying solution, the pH of supporting electrolyte, and preconcentration time were optimized. The interferences of other metal ions were masked by adding KCN and thiourea into the sample solutions. A good linear calibration plot in the range 0.21 ppb (1.0×10^-9 M)~20.72 ppb (1.0×10^-7 M) was obtained with a detection limit (3s) of 0.32 ppb (1.54×10^-9 M) in pH 4.0 buffer solution. The procedure proposed was applied to the determination of lead (II) in a certified reference material, river water, and seawater. Satisfactory accu racy was obtained for lead (II) in a certified reference material. For river water and seawater, also the results agree satisfactorily with the values analyzed by inductively coupled plasma mass spectrometry (ICP/MS).