Analysis of doxycycline by capillary electrophoresis - Method development and validation

An optimized capillary electrophoresis method for the analysis of doxycycli ne is described. The influence of methanol as organic modifier, buffer pH, buffer concentration, capillary length, column temperature, Triton X-100 an d methyl-beta -cyclodextrin was systematically investigated. A central comp osite design was performed in order to optimize the method. The optimal sep aration conditions were: capillary, uncoated fused-silica [40 cm (32 cm eff ective length)X50 mum I.D.]; background electrolyte, a solution of 145 mM s odium carbonate and I mM EDTA brought to pH 10.3-methanol (89:11, v/v); tem perature, 15 degreesC; voltage, 12 kV. The method showed good selectivity, repeatability, linearity and sensitivity. Six commercial samples were quant itatively analyzed. The results were compared with those established by the liquid chromatography method from the European Pharmacopoeia. (C) 2000 Els evier Science B.V. All rights reserved.