Determination of phenylpyruvic acid in urine and serum by high-performance liquid chromatography with fluorescence...

A highly sensitive and simple method for the determination of phenylpyruvic acid in urine and serum is described which employs high-performance liquid chromatography with fluorescence detection. Phenylpyruvic acid, after extraction with ethyl acetate, is reacted with 4'-hydrazino-2-stilbazole in aqueous methanol to give the corresponding fluorescent hydrazone which is separated by reversed-phase chromatography on muBondapak Phenyl. The lower limits of detection are 25 and 32 pmol for phenylpyruvic acid in 0.2 ml of urine and serum, respectively. This sensitivity permits the determination of the acid in urine or normal adults and newborn infants.