Quantitative analysis of the isomers of hydroxyphenylalanine by ion-exchange chromatography.

A method for separatory determination of the isomers of hydroxyphenylalanine by liquid chromatography was established. The chromatographic conditions were as follows : Column, glass column (0.9×50cm) packed with Hitachi #2612 ion-exchange resin ; mobile phase, 0.2M citrate buffer (pH 2.80) and 0.2M citrate buffer (pH 3.90) ; flow rate, 1.0 ml/min ; temperature change from 30°to 55°at 3.25 hr ; buffer change at 1.5 hr ; detector, ultraviolet and visible detector.