Voltammetry and determination of metronidazole at a carbon fiber microdisk electrode.

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 4x10(3)mol(-1)dm(3) and a saturation coverage of 0.88x10(-8)molcm(-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 5x10(-7)moldm(-3) and a R.S.D. of 3.7% at 1x10(-6)moldm(-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.