Determination of cadmium(II) using carbon paste electrode modified with a Cd-ion imprinted polymer

We have synthesized cadmium(II) ion-imprinted polymers (IIP) and non-imprinted polymers (NIP) using 1-(2-pyridylazo)-2-naphthol as a ligand. The materials were used to prepare a carbon paste electrode for the determination of Cd(II). Polymerization was performed with (a) methacrylic acid as a functional monomer, (b) ethyleneglycol dimethacrylate as the crosslinking monomer, and (c) 2,2'-azobis(isobutyronitrile) as the initiator. Imprinted cadmium ion was removed from the polymeric matrix using nitric acid. The measurements were carried out in an closed circuit after accumulation at -1.2 V, this followed by electrolysis of the accumulated Cd(II) by voltammetric scanning from -1.0 to -0.6 V. The parameters governing the response of the electrode were studied. Under optimized conditions, the response of the electrode is linear in the range from 2.0 to 200 ng mL(-1). The detection limit is 0.31 ng mL(-1). The relative standard deviations are +/- 3.4 and +/- 2.1 % for 7 successive determinations of 20.0 and 50.0 ng mL-1 of Cd(II), respectively. The method was applied to the determination of cadmium (II) in water and food samples.