A novel electrochemical immobilization of Hg in CdSe QDs - modified graphite electrode and its improved performance in voltammetric determination of lead (II) ion

Abstract

A novel metal ion sensor was fabricated through electrochemically immobilized Hg spheres on surface-unpassivated CdSe quantum dots modified paraffin wax impregnated graphite electrode. The size and surface morphology of the CdSe QDs and CdSe QDs - Hg modified electrode was characterized by transmission electron microscope and field emission scanning electron microscopy. The modified electrode was also characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The modified electrode was used for the determination of trace level lead ion which was preconcentrated onto the modified electrode by differential pulse anodic stripping voltammetry (DPASV). Numerous key variables affecting the current response of lead ion have been optimized. The proposed electrode has a linear concentration range of 5.2 ng/L–4.2 µg/L with a optimized deposition time of 180 s and the detection limit is found to be 1.7 ng/L (S/N = 3). The electroanalytical performance of the modified electrode was successfully tested in a real sample of tap water and sea water spiked with Pb(II) ion. The proposed electrode shows excellent selectivity and sensitivity over other heavy metals, such as copper, zinc, manganese and tin. Hg(II) immobilized CdSe QDs modified electrode has shown great potential application in detecting metal ions at very low concentrations.