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.
