An electrochemical sensor based on graphene/polyaniline/polystyrene nanoporous fibers modified electrode for simultaneous determination of lead and cadmium

The development of graphene/polyaniline/polystyrene (G/PANI/PS) nanoporous fiber modified screen printed carbon electrode (SPCE) using electrospinning fabrication for simultaneous determination of lead (Pb2+) and cadmium (Cd2+) was achieved. Initially, the important factors controlling the electrospun fiber morphology and electrochemical sensitivity (e. g. type of solvent, amount of G loading) were investigated and optimized. Then, the electrospun G/PANI/PS nanoporous fibers were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Cyclic voltammetric (CV) measurements using a standard ferri/ferrocyanide [Fe(CN)(6)](3-/4)- redox couple were performed for electrochemical characterization of the modified electrode. Due to the increase of specific surface area of the electrospun G/PANI/PS nanoporous fibers, the electrochemical sensitivity of modified SPCE was enhanced by a factor of three compared to an unmodified SPCE. In terms of application, square-wave anodic stripping voltammetry (SWASV) was employed for the simultaneous determination of Pb2+ and Cd2+ in the presence of bismuth (Bi3+) on G/PANI/PS nanoporous fiber-modified SPCE. Under optimal conditions, a linear relationship between anodic current and metal ion concentration was found in a range of 10-500 mu g L-1 with the detection limit (S/N = 3) of 3.30 mu g L-1 and 4.43 mu g L-1 for Pb2+ and Cd2+, respectively. In addition, the effects of common cation and anion interferences commonly found in environmental water were studied, and the satisfied results were obtained. Interestingly, by simple washing step, this described electrode can be reused for more than ten replicates with high reproducibility. Finally, this new electrode system was successfully applied for the simultaneous determination of Pb2+ and Cd2+ in real river water samples, and the results correlated well with conventional inductively coupled plasma optical emission spectroscopy (ICP-OES). (C) 2014 Elsevier B.V. All rights reserved.