Determination of midecamycin by capillary zone electrophoresis with electrochemical detection

Abstract

Capillary zone electrophoresis was employed for the determination of midecamycin using an end-column amperometric detection with a carbon fiber micro-disk bundle electrode at a constant potential of +1.15 V vs. saturated calomel electrode. The optimum conditions of separation and detection are 1.00×10 −3 mol l −1 Na 2HPO 4–3.49×10 −4 mol l −1 NaOH (pH 11.4) for the buffer solution, 20 kV for the separation voltage, 5 kV and 5 s for the injection voltage and the injection time, respectively. The limit of detection is 5.0×10 −7 mol l −1 or 0.41 fmol ( S/N=3). The linear range of the calibration curve is 1.00×10 −6–1.00×10 −3 mol l −1. The relative standard deviation is 1.4% for the migration time and 4.9% for the electrophoretic peak current. The method could be applied to the determination of midecamycin in human urine. In this case, a separation voltage of 14 kV was used.