Abstract
Two simple and sensitive kinetic spectrophotometric methods have been developed and validated for the determination of gatifloxacin (GAT) in its bulk and pharmaceutical dosage forms (tablets). The methods were based on the oxidation of GAT with alkaline potassium permanganate to give a green colored reaction product. The reaction was monitored spectrophotometrically by measuring the absorbance of the reaction product at 610 nm. The factors affecting the reaction was studied and optimized. The stoichiometry of the reaction was determined and the reaction pathway was postulated. Under the optimized conditions, the initial rate and fixed time (at 5 min) methods were utilized for constructing the calibration graphs. The graphs were linear in the concentration ranges of 2-20 and 5-25 mu g/mL with limits of detection of 1.2 and 5.7 mu g/mL for the initial-rate and fixed-time methods, respectively. The analytical performance of both methods was fully validated, and the results were satisfactory. The proposed methods were successfully applied to the determination of GAT in its commercial dosage forms. The label claim percentages were 100.1 +/- 1.35 and 99.6 +/- 1.22% by the initial-rate and fixed-time methods, respectively. Statistical comparison of the results with those of the reference method showed excellent agreement and proved that there was no significant difference in the accuracy and precision between the reference and the proposed methods. The proposed methods are superior to all the previously reported spectrophotometric methods in terms of procedure simplicity and cost.