Voltammetry and determination of metronidazole at a carbon fiber microdisk electrode

Abstract

The electrochemistry of metronidazole, 1-(hydroxyethyl)-2-methyl-5-nitroimidazole, was investigated at a carbon fiber microdisk electrode in pH 9 Britton Robinson buffer. Under these conditions, the reduction of metronidazole is controlled by both mass transport to the microdisk and adsorption with an equilibrium constant of 4 × 10 3 mol −1 dm 3 and a saturation coverage of 0.88 × 10 −8 mol cm −2. The adsorption and accumulation of metronidazole on the surface of the carbon fiber allows its determination at low concentrations by square wave adsorptive stripping voltammetry. A detection limit for metronidazole of 5 × 10 −7 mol dm −3 and a R.S.D. of 3.7% at 1 × 10 −6 mol dm −3 ( n = 4) were obtained with a two electrode system with no stirring during the accumulation step. Based on this method, a simple procedure for the determination of metronidazole in urine is described which requires no pre-treatment of the sample before analysis.