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COMPARATIVE STUDY OF REVERSED-PHASE COLUMNS FOR EVALUATION OF MONOLITHIC STATIONARY PHASE

ABSTRACT A comprehensive study for the determination of different antibiotics, ciprofloxacin and vancomycin, has been carried out using a number of chromatographic stationary phases such as Purospher® RP-18e, Prontosil® 120-5-C18-AQ, Nucleosil® 100-C-8, LiChrosorb® RP-select B, LiChrospher® RP-18, and Chromolith® SpeedRod RP-18e. The commonly used Purospher® RP-18e was taken as a reference column, since this stationary phase has previously been used for determination of antibiotics mentioned above. In the case of different columns, the acetonitrile content of eluent used was adjusted to get the same retention factor as, for instance, Purospher® RP-18e for each antibiotics. Under these conditions, characteristic chromatographic parameters (asymmetry factor, number of theoretical plates) were calculated for every single column. On the basis of asymmetry factors, Prontosil® 120-5-C18-AQ was found to be the best column for ciprofloxacin and Nucleosil® 100-C-8 for vancomycin; whereas, on the basis of theoretical plate numbers, Chromolith® SpeedRod RP-18e proved to be the most outstanding one for ciprofloxacin and Prontosil® 120-5-C18-AQ for vancomycin. Evaluation of the small size Chromolith® SpeedRod RP-18e monolithic stationary phase was set as an aim, as well, to control the applicability of this column as a part of a conventional HPLC-system. Advantages of Chromolith® SpeedRod RP-18e are the low pressure drop and short retention time, therefore, faster analysis of antibiotics can be done.