Spectrophotometric Determination of Nitrazepam Using Phloroglucinol as Coupling Reagent

This paper describes the development of a spectrophotometric method for the determination of nitrazepam after diazotization of its reduced product and coupling with phloroglucinol in basic medium , to form an intense yellow coloured , water soluble and stable azo-dye which shows a maximum absorption at 434 nm. Beers law is obeyed over the concentration range 15 to 200 g/25 ml with a molar absorptivity 6.1183104 l. mol-1.cm-1 and Sandells sensitivity of 0.0046 g.cm-2. The relative error is ranged from -1.6 to 2.8 % and relative standard deviation from 0.1 to 3.3 % , depending on the concentration level.
The method has been applied successfully to the determination of nitrazepam in pharmaceutical preparation (tablet).