CAPILLARY ELECTROPHORESIS OF SOME TETRACYCLINE ANTIBIOTICS

Data on the separation of tetracycline antibiotics by capillary electrophoresis are rather limited and have not been reported for micellar electrokinetic capillary chromatographic separation (MECC). In the present study, the separation of tetracycline, oxytetracycline and chlortetracycline by capillary zone electrophoresis and MECC was investigated. Adding non-ionic surfactants such as Triton X-100 to a 0.2 M phosphate migration buffer of pH 2.2 greatly improved separation. The use of mixed micelles enlarged the variety of the micellar phases, e.g. a combination of Tween 20 and Tween 80 provided a similar separation pattern. The addition of beta-cyclodextrin to a Triton X-100 and Brij-35 surfactant combination did not result in an improved separation. A Triton X-100 and Brij-35 combination could separate tetracycline and its degradation products 4-epitetracycline (ETC), anhydrotetracycline and 4-epianhydrotetracycline. This enabled us to identify ETC in a commercial tetracycline sample.