Square wave voltammetric determination of nitrofurantoin in pharmaceutical formulations on highly boron-doped diamond electrodes at different boron-doping contents

The influence of the boron-doping levels in boron-doped diamond film electrodes on the electrochemical response of nitrofurantoin (NFT) and the development of an electroanalytical procedure for NET determination were investigated. The investigations were carried out using the techniques of cyclic voltammetry and square wave voltammetry on diamond film electrodes with different boron-doping levels (i e.5000. 10,000 and 20,000 mg L(-1)) The level of boron-doping ill the diamond film electrodes influenced the electrochemical reduction of NET. The appropriate cyclic voltammetric response of NET was obtained with Britton-Robinson buffer at pH 4 and for diamond films doped with 10,000 and 20,000 mg L-1 of boron These two films were selected for the development of the electroanalytical procedure. The use of square wave voltammetry with the optimized parameters demonstrated a good linear relationship between the peak current and the NET concentration for a wide range of concentration. The lower limit of detection for the electrodes doped with 10,000 and 20.000 mg L(-1) of boron were 269 x 10(-8) mol L(-1) (6 40 mu g L(-1)) and 8 15 x 10(-9) mol L(-1) (1 94 mu g L(-1)), respectively. while the lower limits of quantification were 8.96 x 10(-8) mol L(-1) (21 33 mu g L(-1)) and 2.72 x 10(-8) mol L(-1) (6.47 mu g L(-1)), respectively. The applicability of the proposed procedure was tested using a commercial pharmaceutical formulation of NFT, and the results were compared with the procedure recommended by the British Pharmacopeia. The proposed procedure was sensitive, accurate and precise for analysis of NET and did not require complex preparations or renovations of the electrode surface This presents the advantage of eliminating mercury waste and minimizing the adsorptive problems related to the use of other electrodic solid surfaces. (C) 2009 Elsevier B.V. All rights reserved.