Anion exchange groups were introduced into porous hollow fiber membranes by radiation-induced ploymerization. The epoxy group produced in the GMA-grafted hollow fiber membrane was converted into anion-exchange groups by reaction with Diethylamine(DEA), Triethylamine(TEA), Ethanolamine(EtA), Diethanolamine(DEtA). The D-, L-Tryptophan solution was forced to permeate across the hollow fiber DEA, TEA, EtA, DEtA membrane. When measurements of anion-exchange capacity of the DEA, TEA, EtA, DEtA membrane, the DEA membrane having higher adsorption capacity than TEA, EtA, DEtA membrane.