Spectrophotometric determination of azithromycin in pharmaceutical formulations employing the reaction with alizarin

Abstract

In this work, a spectrophotometric method was developed for the quantification of azithromycin (AZ) in pharmaceutical formulations using a flow injection analysis system (FIA). The method was based on the acid-base reaction of azithromycin with alizarin (ALZ) in aqueous medium. The substance formed was measured spectrophotometrically at 525 nm. After the optimization of the physical and chemical variables, the Lambert Beer's law was obeyed in the concentration range of 8-40 mg L-1 and 4-20 mg L-1, for the method with and without the FIA system, respectively, The molar absorptivity of the substance measured was 3.06 x 103 L mol-1 cm-1. The two quantification strategies were applied for the determination of azithromycin in pharmaceutical formulations and the obtained results were statistically equivalent.