Determination of 3-chloro-N-chloro-N-(3,4-dimethyl-5-isoxazolyl)-4-amine-1,2-naphthoquinone in presence of its degradation products using second derivative spectrophotometry

A rapid, selective and accurate method for stability determination of 3-chloro-N-chloro-N-(3,4-dimethyl-5-isoxazolyl)-4-amine-1,2-naphthoquinone (1b) in the presence of its degradation products by using second derivative UV spectrophotometry was developed. The validity of this method was proved using synthetic mixtures of the intact drug with its decomposition products and by statistical analysis of the calibration data. Lack of interference between the signals was observed in an interaction study. The synthesis of 1b and its degradation product 3-chloro-2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinon-4-imine (2b) are also described.