Analysis of ampicillin, cloxacillin and their related substances in capsules, syrups and suspensions by high-performance liquid chromatography

Abstract

An assay method for the simultaneous determination of ampicillin (AMP) and cloxacillin (CLOX) from pharmaceutical preparations has been developed for assessment of product quality. It utilizes isocratic HPLC employing an ion-pairing solvent system. The chromatographic conditions comprised a reversed-phase C₁₈ column (100 × 2 mm id) with a mobile phase of acetonitrile–20 mmol l^–1 aqueous phosphate buffer (15 + 85) of pH 2.0 incorporating 100 mmol l^–1 sodium dodecyl sulfate. The flow rate was 0.4 cm³ min^–1 and UV detection was used at 230 nm. A photodiode array detector was used for examination of peak homogeneity. The method has been validated according to current guidelines including assay of pharmacopoeial standard Ampiclox capsules, syrups and neonatal suspensions. In addition to determination of the active ingredients, AMP and CLOX, the method is capable of simultaneously detecting manufacturing precursors and acid hydrolysis decomposition products of both drugs.