Kinetic Determination of Nitrazepam in Tablets

A kinetic method for the determination of nitrazepam by the continuous addition of reagent (CAR) technique is reported. The method involves the formation of an azo dye between 1-naphthol and a diazonium salt that is in turn obtained by reaction between 2-amino-7-nitrobenzophenone (the hydrolysis product of the drug) and sodium nitrite. The reaction is monitored by measuring the rate of change of the absorbance of the azo dye formed at 600 nm which is proportional to the nitrazepam concentration. The linear range of the determination is 0.58–2.90 gml-1 and the relative standard deviation is 0.47%. The method is quite simple and was applied to the analysis of pharmaceutical samples, the results obtained being highly consistent with the certified contents.