Spectrophotometric determination of Metronidazole and Secnidazole in pharmaceutical preparations based on the formation of dyes

A rapid and sensitive spectrophotometric method is proposed for determination of Metronidazole and Secnidazole. The method depends on the reduction of Metronidazole and Secnidazole molecule with zinc dust and hydrochloric acid flowed by diazotization and coupling with β-naphtol to give red colored chromogens easily measured spectrophotometrically which has λmax = 510 nm. The experimental conditions were optimized and Berr's law was obeyed over the applicable concentration ranges. Both techniques were applied successfully to a wide variety of pharmaceutical preparations.