Electrochemical detection of methimazole by capillary electrophoresis at a carbon fiber microdisk electrode

We developed a sensitive, simple and low cost method to determine methimazole based on capillary electrophoresis with electrochemical detection (CE-EC) at a carbon fiber microdisk electrode (CFE). We investigated the effects of detection potential, the concentration and pH value of the phosphate buffer, and injection time as well as separation voltage on the detection of methimazole. Under the optimized conditions: the detection potential at 1.30 V, 10 mmol/L phosphate buffer (pH 7.0), injection time 30 s at a height of 20 centimeter and separation voltage at 15 kV, the linear range was obtained from 1.0 x 10(-7) to 2.0 x 10(-4) mol/L, covering 3 orders of magnitude with a correlation coefficient of 0.9995. The LOD (S/N 3) obtained was 5.0 x 10(-8) mol/L. The RSD of migration time and peak current for 2.0 x 10(-4) mol/L methimazole was 1.04% and 1.54% (n = 10), respectively. The method was also used to analyze methimazole tablets and human urine sample.