Journal of Chromatography vol:634 issue:2 pages:257-261
A comparative study of two isocratic liquid chromatographic methods for the determination of cefadroxil is described. The first method, prescribed in the monograph of the European Pharmacopoeia for the assay of cefadroxil, uses a classical alkyl-bonded phase (C18) as the stationary phase. This method is very similar to that prescribed by the United States Pharmacopeia. The other method uses poly(styrene-divinylbenzene). Poor reproducibility of the selectivity towards cefadroxil and related substances was observed when the first method was examined on different C18 columns. Copolymer columns, on the other hand, gave the same elution order on stationary phases from different manufacturers and of different age. Four bulk samples of cefadroxil were analysed following both methods and the results were compared.