High-sensitivity determination of lead and cadmium based on the Nafion-graphene composite film.

Graphene nanosheets, dispersed in Nafion (Nafion-G) solution, were used in combination with in situ plated bismuth film electrode for fabricating the enhanced electrochemical sensing platform to determine the lead (Pb2+) and cadmium (Cd2+) by differential pulse anodic stripping voltammetry (DPASV). The electrochemical properties of the composite film modified glassy carbon electrode were investigated. It is found that the prepared Nafion-G composite film not only exhibited improved sensitivity for the metal ion detections, but also alleviated the interferences due to the synergistic effect of graphene nanosheets and Nafion. The linear calibration curves ranged from 0.5 microg L(-1) to 50 microg L(-1) for Pb2+ and 1.5 microg L(-1) to 30 microg L(-1) for Cd2+, respectively. The detection limits (S/N=3) were estimated to be around 0.02 microg L(-1) for Pb2+ and Cd2+. The practical application of the proposed method was verified in the water sample determination.