Extractive-spectrophotometric determination of some phenothiazines with dipicrylamine and picric acid

Dipicrylamine and picric acid have been tested as reagents for the determin ation of promethazine and perphenazine. They react in neutral media with th ese drugs forming the coloured compounds. The compounds are sparingly solub le in water and quantitatively extracted into organic solvents. The extract s are intensely coloured and very stable. These properties have been exploi ted for the extractive spectrophotometric determination of promethazine and perphenazine in pure solutions and pharmaceuticals. Linear calibration gra phs were obtained in the concentration range 4-40, 3-30 mug ml(-1) of prome thazine and 4-80, 8-60 mug ml(-1) of perphenazine for picric acid and dipic rylamine, respectively. The relative standard deviation (RSD) is less than 0.8%. (C) 2002 Elsevier Science B.V. All rights reserved.