New, simple and validated UV-spectrophotometric methods for the estimation of gatifloxacin in bulk and formulations

New, simple and cost effective UV-spectrophotometric methods were developed for the estimation of gatifloxacin in bulk and pharmaceutical formulations. Gatifloxacin was estimated at 286 nm in 100 mM phosphate buffer (pH 7.4) and 292 nm in 100 mM hydrochloric acid (pH 1.2). Linearity range was found to be 1–18 μg ml^–1 (regression equation: absorbance = 0.0684 × Concentration in μg ml^–1 + 0.0050; r² = 0.9998) in the phosphate buffer (pH 7.4) and 1–14 μg ml^–1 (regression equation: absorbance = 0.0864 × Concentraion in μg ml^–1 + 0.0027; r² = 0.9999) in hydrochloric acid medium (pH 1.2). The apparent molar absorptivity was found to be 2.62 × 10⁴ l mol⁻¹ cm⁻¹ in the phosphate buffer and 3.25 × 10⁴ l mol⁻¹ cm⁻¹ in hydrochloric acid media. In both the proposed methods sandell's sensitivity was found to be about 0.01 μg cm⁻²/0.001A. These methods were tested and validated for various parameters according to ICH guidelines and USP. The quantitation limits were found to be 0.312 and 0.3 μg ml^–1 in the phosphate buffer and hydrochloric acid medium, respectively. The proposed methods were successfully applied for the determination of gatifloxacin in pharmaceutical formulations (tablets, injection and ophthalmic solution). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation < 2%), while being simple, cheap and less time consuming and can be suitably applied for the estimation of gatifloxacin in different dosage forms and dissolution studies.