Three simple, accurate and economical methods have been developed for the estimation of norfloxacin and ornidazole in tablet dosage form. First method is based on the simultaneous equations, wavelengths selected for analysis were 273.0 nm (lambda(max) of norfloxacin) and 318.5 nm (lambda(max) of ornidazole), respectively, in 0.1N NaOH. Second method is Q-analysis method, based on absorbance ratio at two selected wavelengths 297.0 nm (iso-absorptive point) and 318.5 nm (lambda(max) of ornidazole). Third method is first order derivative spectroscopy using 297.5 nm (zero cross for norfloxacin) and 264.0 nm (zero cross for ornidazole). The linearity was obtained in the concentration range of 4-20 mug/ml and 5-25 mug/ml for norfloxacin and ornidazole, respectively. The results of the analysis have been validated statistically and by recovery studies.
Keywords: Norfloxacin; Q-analysis; derivative spectroscopy; ornidazole; simultaneous equation.