Simultaneous quantitation of some phenothiazine drug substances and their monosulphoxide degrades by high performance liquid chromatography (HPLC)

A simple liquid chromatographic procedure is presented for the simultaneous quantitation of three phenothiazine drugs, namely, perphenazine, trifluoperazine and triflupromazine and their sulphoxide degrades. The LC-separation was performed on a Novapak-phenyl-4 (150 x 3.9 mm id) column and a mobile phase composed of methanol + 1.5 x 10(-2) M sodium acetate buffer pH 6.5 (81:19, v/v). Isocratic elution and UV-detection were adopted. Satisfactory percent assay and mean recoveries with low relative standard deviations were obtained for each drug and its sulphoxide in bulk and in tablet dosage form. The stability-indicating characteristics of LC-procedure prove its advantage over the methods used to limit the sulphoxides.