DEVELOPMENT OF A CAPILLARY ELECTROPHORETIC METHOD FOR THE SEPARATION OF THE MACROLIDE ANTIBIOTICS, ERYTHROMYCIN, JOSAMYCIN AND OLEANDOMYCIN

Capillary electrophoresis (CE) provides high separation efficiency and thus is suitable for the analysis of complex mixtures of structurally similar compounds. The versatile nature of CE can be realised by cont rolling the chemistry of the inner capillary wall, by modifying the el ectrolyte composition and by altering the physicochemical properties o f the analyte. A CE method has been developed for the separation of th ree macrolide antibiotics, erythromycin, oleandomycin and josamycin. A systematic approach was used to maximise analyte differential electro phoretic mobility by manipulating electrolyte pH, molarity and composi tion. In addition, some instrumental parameters such as capillary leng th and diameter and applied voltage were varied. The effect of the sam ple solvent and on-capillary concentrating techniques such as field am plified sample injection were investigated. Also, the influence of the injection of a water plug on the quantity of sample injected was demo nstrated. The macrolides were completely resolved in less than 30 min in a 100 cmX75 mu m I.D. fused-silica uncoated capillary with a Z-shap ed flow cell of path-length 3 mm. The analysis was performed in a 75 m M phosphate buffer (pH 7.5) with 50% (v/v) methanol and an applied vol tage of 25 kV was selected to effect the separation. (C) 1997 Elsevier Science B.V.