Determination of cadmium(II) using glassy carbon electrodes modified with cupferron, β-naphthol, and multiwalled carbon nanotubes

We report on a simple and reliable method for the determination of trace cadmium ion using a glassy carbon electrode (GCE) modified with cupferron, beta-naphthol and MWCNTs. The operational mechanism consists of several steps: first, the ligand cupferron on the modified electrode reacts with Cd2+ ion to form a chelate compound. Next, this chelate is adsorbed by the carrier beta-naphthol following the principle of organic co-precipitation. Finally, the coprecipitated complex is detected by the GCE. This scheme is interesting because it combines preconcentration and electrochemical detection. Two linear responses are obtained, one in the concentration range of 5.0x10(-11) to 1.6x10(-8) M, the other in the range of 1.6x10(-8) to 1.42x10(-6) M, with a lower detection limit of 1.6x10(-11)M. This modified GCE does not suffer from significant interferences by Cu(II), Hg(II), Ag(I), Fe(III), Pb (II), Cr(III), Zn(II), NO3-, Cl-, SO42- ions and EDTA. The response of the electrode remained constant for at least 3-weeks of successive operation. The method presented here provides a new way for the simultaneous separation, enrichment, and electrochemical detection of trace cadmium ion.