CAPILLARY ELECTROPHORESIS OF SOME TETRACYCLINE ANTIBIOTICS

Data on the separation of tetracycline antibiotics by capillary electr ophoresis are rather limited and have not been reported for micellar e lectrokinetic capillary chromatographic separation (MECC). In the pres ent study, the separation of tetracycline, oxytetracycline and chlorte tracycline by capillary zone electrophoresis and MECC was investigated . Adding non-ionic surfactants such as Triton X-100 to a 0.2 M phospha te migration buffer of pH 2.2 greatly improved separation. The use of mixed micelles enlarged the variety of the micellar phases, e.g. a com bination of Tween 20 and Tween 80 provided a similar separation patter n. The addition of beta-cyclodextrin to a Triton X-100 and Brij-35 sur factant combination did not result in an improved separation. A Triton X-100 and Brij-35 combination could separate tetracycline and its deg radation products 4-epitetracycline (ETC), anhydrotetracycline and 4-e pianhydrotetracycline. This enabled us to identify ETC in a commercial tetracycline sample.