Determination of Trace Lead and Cadmium in Water Samples by Anodic Stripping Voltammetry with a NafionIonic Liquid-Coated Bismuth Film Electrode

A new chemically modified bismuth film electrode coated with an ionic liquid [(1-ethyl-3-methylimidazolium tetracyanoborate (EMIM TCB)] and Nafion was developed for the simultaneous determination Pb2+ and Cd2+ by anodic stripping voltammetry. Compared with conventional bismuth film electrodes, this electrode exhibited greatly improved electrochemical activity for Pb2+ and Cd2+ detection due to the unique properties of Nafion polymer and ionic liquid. The key experimental parameters related to the fabrication of the electrode and the voltammetric measurements were optimized on the basis of the stripping signals, where the peak currents increased linearly with the metal concentrations in a range of 10-120 mu gL(-1) with a detect limit of 0.2 mu gL(-1) for Pb2+, and 0.5 mu gL(-1) for Cd2+ for 120s deposition. High reproducibility was indicated from the relative standard deviations (1.9 and 2.5%) for nine repetitive measurements of 20 mu gL(-1) Pb2+ and Cd2+, respectively. In addition, the surface characteristics of the modified BiFE were investigated by scanning electron microscopy (SEM), and results showed that fibril-like bismuth nanostructures were formed on the porous Nafion polymer matrix. Finally, the developed electrode was applied to determine Pb2+ and Cd2+ in water samples, indicating that this electrode was sensitive, reliable and effective for the simultaneous determination of Pb2+ and Cd2+.