An Isocrstic Reversed—Phase Separation and Determination of and Phenytoin in Tablets by High Performance Liquid Chromatogrphy

An isocratic, sensitive high-per-Formance liquid chromatographic method has been developed for the determination of phenobarbitone, methylphenobarbitone and phenytoin in tablets. A reversed-phase octadecylsilane column, 10 µ, was utilized with a mobile phase consisting of 45% methanol, 55% water and 0.5 ml glacial acetic acid at a flow rate of 1.8 ml/min. The samples were dissolved in methanol containing diethylbarbituric acid as an internal standard. Quantitation was achieved with UV detection at 240 nm and by the measurment of the peak area ratio.