Indirect titrimetric anti spectrophotometric methods for the determination of some phenothiazine psychotropics

A titrimetric and a spectrophotometric method herein described for the determination of phenothiazine psychotropics. In the titrimetric method, phenothiazines are reacted with a known excess of potassium dichromate under acidic conditions and after the completion of the reaction, unreacted dichromate is backtitrated with ammonium ferrous sulphate, In the spectrophotometric method, the unreacted dichromate is reacted with s-diphenylcarbazide under acidic conditions and the absorbance measured at 540 nm. The proposed methods were successfully applied to the determination of phenothiazines in pharmaceutical preparations. The reliability of the assays was established by parallel determination by the official methods of British pharmacopoeia.