Sensitive spectrophotometric assay of psychoactive drug in pharmaceutical formulations and in biological fluids using redox reaction

This paper reports on the analytical application of the oxidation reaction of psychoactive drug, chlorpromazine HCl (CPZ) by N-bromosuccinimide and potassium permanganate. The present study develops four new, simple, sensitive and selective spectrophotometric methods for the analysis of chlorpromazine HCl (CPZ) in dosage forms and in biological fluids. The methods are based on the oxidation of chlorpromazine HCl by a known excess of N-bromosuccinimide and potassium permanganate under acidic conditions followed by the determination of unreacted oxidants by four different reaction schemes. The amount of oxidants reacted corresponds to drug content. The apparent molar absorptivity values are in the range 8.24 x 10(3)-3.7 x 10(4) L/mol cm and the limits of determination range from 0.1555 to 0.3002 mu g/mL. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The methods are highly reproducible and have been successfully applied to the assay CPZ in pharmaceuticals, serum and urine samples and average recoveries are in the range of 97.05-103.26\%. A statistical comparison of these results with those of a reported method shows good agreement and indicates no significant difference in precision.