FLOW-INJECTION SPECTROPHOTOMETRIC DETERMINATION OF PHENOTHIAZINES USING ANALYTE OXIDATION IN MANGANESE DIOXIDE-PACKED REACTORS

A flow-injection spectrophotometric method for determining 5 to 250 mu g.ml(-1) of neuroleptic phenothiazines (namely prochlorperazine, thio ridazine, levomepromazine, perphenazine, trifluoperazine and fluphenaz ine) using the analyte oxidation in manganese dioxide-packed reactors (50 mm x 1.2 mm) with aqueous 0.01 M sulphuric acid as carrier flow (0 .6 ml.min(-1)) has been devised. Active and stable reactor packings we re prepared by coating sintered glass particles (diam. 0.4 to 0.5 mm) successively with an epoxide glue and powdered manganese dioxide or by thermal decomposition of Amberlite IRA-410 resin (20-50 mesh) in MnO4 - form. At the injected sample volume of 100 mu l the relative standar d deviation was 1.2% (n = 10) when determining 75 mu g.ml(-1) of proch lorperazine maleate in prepared solution of the pure substance and the sample throughput was 50 h(-1). The method has been applied to the an alysis of tablets and coated tablets containing prochlorperazine malea te, perhenazine, thioridazine hydrochloride or levomepromazine maleate . The results were in good agreement with those of the pharmacopoeial UV spectrophotometric determination.