Spectrophotometric determination of phenobarbitone, methylphenobarbitone and phenytoin in tablets

Abstract

Two procedures for the determination of phenobarbitone, methylphenobarbitone and phenytoin in compound tablets are presented. The first depends on the determination of methylphenobarbitone from the change in its absorbance at 246 nm after treatment with sodium hydroxide (the ΔA method) and of the other two compounds by the modified Vierordt method. The second procedure depends on the application of the least-squares method to the simultaneous determination of the three compounds without separation. The results obtained using synthetic mixtures and commercial tablets were concordant, precise and accurate.