A New Type of Large-Surface Bismuth Film Electrode on a Silver Solid Amalgam Substrate and its Application for the Voltammetric Determination of 5-Nitrobenzimidazole

A novel type of large-surface bismuth film electrode prepared by electrochemical deposition of bismuth on a silver solid amalgam electrode (LSBiF-AgSAE) was developed. A silver solid amalgam substrate with a diameter of 2.64 mm was used to achieve larger surface of this electrode resulting in higher sensitivity in the voltammetric analysis. The larger electrode surface required longer time (i.e., 1800 s) for the electrochemical deposition of the bismuth film. The electrode surface of thus prepared electrode was characterized by atomic force microscopy (AFM) which confirmed that the bismuth film was not grown uniformly over the supporting surface, but created three-dimensional higher formations which cover only a fraction of the surface. To verify the practical application of the new LSBiF-AgSAE, the voltammetric behavior of genotoxic 5-nitrobenzimidazole (5-NBIA) was investigated using direct current voltammetry (DCV) and differential pulse voltammetry (DPV), and optimum conditions were found for its determination in the concentration range from 0.2 to 1000 mu mol L-1 in the Britton-Robinson buffer solution (pH 7.0), with the limits of quantification (L(Q)s) 0.37 mu mol L-1 (DCV) and 0.07 mu mol L-1 (DPV). An attempt to increase the sensitivity using adsorptive stripping DCV or DPV at the BiF-AgSAE was not successful. The practical applicability of the newly developed electrode was verified on direct determination of 5-NBIA in tap and mineral water model samples, with L(Q)s approximate to 0.1 mu mol L-1 mol L-1.