Facile and manifest spectrophotometric methods for the determination of six quinolone antibiotics in pharmaceutical formulations using iron salts

Abstract

Simple spectrophotometric methods have been developed for the determination of six quinolone antibiotics, namely, ciprofloxacin, gatifloxacin, norfloxacin, levofloxacin, ofloxacin, and pefloxacin, in pharmaceutical formulations using three different salts of iron. These methods are based on the formation of complexes with ferric nitrate, ferric chloride, or iron ammonium citrate in which the carboxylic group of quinolones undergoes complexation with iron. The complexes formed in these reactions, having a brown color, were measured at their respective λmax values. The increase in absorbance was directly proportional to the concentration of quinolones and obeys Beer’s law in the range of 6–300 μg mL−1 (r ≥ 0.9999). The proposed methods were optimized and validated per the guidelines of the International Conference on Harmonization. The proposed methods were successfully employed for determination of these quinolones in pharmaceutical formulations.