Spectrophotometric determination of some sulphonamide drugs via oxidative coupling with phenothiazine and benzoyl peroxide using flowinjection technique

Abstract EN

A novel flow injection Spectrophotometric method is described for the determination of microgram amounts of sulphonamides in aqueous and biological samples.

The method is based on the oxidative coupling reaction of phenothiazine with sulphonamide drugs in the presence of benzoyl peroxide as oxidising agent.

Intense bluish-green, water soluble stable dye was obtained which has a maximum absorption at 614 nm.

Linear calibration graphs were obtained for different sulphonamides with a molar absorptivities of 3250-4720 1.

mol'' cm " and a relative standard deviation of better than 0.84 %.

The proposed method has proved to be highly sensitive (detection limit range 0.30-0.63 p g ml-1 sulphonamide) and accurate (recovery % was 97.9-100.2 %)).

Optimum concentrations of chemical reactants, physical instrumental conditions and effects of interferences from certain additives have been investigated.

The nature of the coloured produced dye and its stability constant were determined.

The method was applied successfully for the determination of sulphonamide drugs in pharmaceutical preparations, blood and urine samples.