Analysis of chlortetracycline and related substances by capillary zone electrophoresis: Development and validation

A capillary zone electrophoresis method has been developed and validated fo r the analysis of chlortetracycline and related substances. The influence o f the type of buffer, pH and concentration of the buffer were investigated. In all cases 1 mM EDTA was added to prevent metal ion complexation. Instru mental parameters such as capillary temperature and applied voltage were op timised. The following method is proposed: capillary: fused silica, 44 cm ( 36 cm effective length), 50 mu m i. d.; buffer: 120 mM sodium tetraborate i ncluding 1mM EDTA at pH 8.5; voltage: 10 kV; temperature: 25 degrees C; det ection wavelength: 280 nm. The robustness of the method has been examined b y means of a full-fraction factorial design. The parameters for validation namely relative standard deviation, linearity, precision, limit of detectio n and limit of quantitation are also reported.