Optimization of the separation of a group of antifungals by capillary zone electrophoresis

Two simple, rapid, and efficient methods for the analysis of seven antifungal compounds have been developed by capillary zone electrophoresis. Resolutions higher than 1.5 were obtained using 0.025 M phosphate buffer (pH 2.30) (analysis time close to 9 min) or 0.2 M formic acid (pH 2.15) (analysis time close to 6 min), with an applied voltage of 20 kV and a temperature of 30°C. The highest sensitivity and selectivity can be obtained using phosphate buffer but the shortest analysis times are achieved in the formic system. The analytical characteristics of the optimized methods were investigated. The reproducibility obtained for migration times (RSDn=10≤1.0%) and peak areas (RSDn=10≤4.3%) was acceptable, but better reproducibilities were obtained when verapamil was used as internal standard (RSDn=10<0.4% for relative migration times and RSDn=10≤2.2% for peak area ratios). The lowest limit of detection was obtained for clotrimazole (0.12 μg/ml) and the highest for fluconazole and voriconazole (0.90 μg/ml). The lowest and the highest limits of quantitation were, respectively, 0.40 μg/ml for clotrimazole and 3.00 μg/ml for fluconazole and voriconazole.