DESIGN OF MICELLAR MATRIX FOR DETERMINATION OF <i>O</i>-PHENYLENEDIAMINE IN DOSAGE FORMS BY SPECTROPHOTOMETRIC METHOD. PLANNING AND OPTIMIZATION
The results of applying the response surface methodology and Box-Behnken plans to create an optimal micellar matrix in order to determine the content of o -phenylenediamine in dosage forms are presented. A system containing ethoxylated nonylphenol (neonol APh<sub>9-6</sub>) in a binary solvent, dimethyl sulfoxide (20 %) + H<sub>2</sub>O (80 %), was used as a micellar matrix. Three-level Box-Behnken plans were used. The intensity of the absorption band of the reaction product of the analyte with the reagent 5,7-dichloro-4,6-dinitrobenzofuroxan at 460 nm (A<sub>460</sub>) was chosen as the objective function, since the content of the analyte was determined from it. The main independent factors influencing the target function of A<sub>460</sub> were the concentration of the reagent, the concentration of neonol APh<sub>9-6</sub>, and the pH of the medium. The properties of the reagent and reaction product are changed due to the solubilization of the reaction participants, and the pH range for analytical determinations is also expanded, up to values of 5-10 units in organized micellar media. A sensitive, selective and rapid method for the spectrophotometric determination of o-phenylenediamine has been developed, which has good metrological characteristics.