Chem. Pharm. Bull. 55(11) 1551—1556 (2007)

synthetic antibacterial agents, which are active against Gram positive and Gram negative bacteria. They are receiving a significant attention due to their broad spectrum of activity, potency, variable indications and excellent pharmacokinetic profiles. Because of their therapeutic importance, numerous analytical methods have been developed for their determinations in pharmaceutical formulations and/or biological fluids; comprehensive reviews for these methods were presented by Carlucci G. and Belal F. et al. Spectrophotometry, because of its inherent simplicity, low cost, and wide availability in most quality control laboratories comprises the most widely used technique for determination of FQA in bulk and pharmaceutical dosage forms. N-Haloimides have been used as effective analytical reagents for the spectrophotometric determination of many pharmaceutical compounds via oxidation or bromination of these compounds. N-Bromosuccinimide (NBS), being the most versatile one, is the most commonly used. The use of NBS as an analytical reagent offered adequate sensitivity and accuracy, in addition to the simplicity and low cost of the analytical method. The use of NBS for the determination of FQA has not been reported yet. Therefore, the present study was undertaken to evaluate NBS as an analytical reagent for the spectrophotometric determination of FQA. The analytical procedure involved the treatment of the FQA with NBS and subsequent measurement of the excess NBS by its reaction with p-phenylenediamine (PDA) to give a violet colored product that was measured at 530 nm.