Mixed micellar liquid chromatographic method for simultaneous determination of norfloxacin and tinidazole in pharmaceutical tablets

A new green mixed micellar liquid chromatographic method was developed, validated, and successfully applied for the determination of norfloxacin and tinidazole in bulk and in pharmaceutical dosage form. The developed method used the anionic surfactant; sodium dodecyl sulphate and the neutral surfactant polyoxyethylene (23) lauryl ether without need of organic solvent in the mobile phase. Optimization of the chromatographic condition was performed by 2(3) full factorial design. Chromatographic separation and quantitation was performed on ODS Hypersil (R) column (250 x 4.6 mm, 5 mu m). Mixed-micellar mobile phase consisted of 0.14 M SDS, 0.03 M Brij-35 and 0.3% triethylamine. pH of the mobile phase was adjusted to 2.9 by orthophosphoric acid. The flow rate was 1 mL/min. The injection volume was 20 mu L. UV detection was performed at 313 nm. Linearity ranges were found to be 2-10 mu g/mL and 2-12 mu g/mL for norfloxacin and tinidazole, respectively. The developed method was validated and successfully applied to the simultaneous determination of both drugs in their tablet. The mean percentage recovery +/- S.D. values were found to be 97.745 +/- 0.664 and 100.441 +/- 1.379 for norfloxacin and tinidazole, respectively. The assay results obtained were statistically compared to those obtained by a reported method and good agreement was observed. The present method offers significant advantages compared to previously reported chromatographic methods concerning column efficiency, selectivity and resolution. The green property of the method was evaluated. The method is verified to obtain excellent greenness. The calculated analytical Eco-Scale of the method was also compared to those of other reported liquid chromatographic methods.