A New Charge Transfer Reaction for Spectrophotometric Determination of Nitrazepam Using Reverse Flow Injection Analysis

A new sensitive spectrophotometric method conjugated with reverse flow-injection analysis has been developed for the assay of nitrazepam (NZP) in the bulk drug and dosage form. The proposed method is based on the formation of charge-transfer complex between reduced NZP (donor) with a new reagent (acceptor) namely, 4,4'-tetramethyl-diaminodiphenyl-methane in the presence of NaIO4 as an oxidant. A violet-colored product was quantified spectrophotometrically at 560 nm. All the chemical and physical conditions of the reaction have been studied carefully. Under the selected optimum conditions, Beer's law was obeyed in the concentration range of 5-300 mu g/mL. The limits of detection and quantification were 5 and 16 mu g/mL, respectively, with a sampling frequency of 62 sample/h. The proposed method was further successfully applied for the assay of NZP in commercial dosage forms and compared statistically with the reference method using t- and F-tests. The method was characterized by its accuracy and simplicity.