Chiral Separation of DL-Tryptophan Using Bovine-Serum-Albumin-Multilayered Porous Hollow-Fiber Membrane

A diethylamino (DEA) -group-containing polymer chain was grafted onto a porous polyethylene membrane in the form of a hollow fiber by radiation-induced graft polymerization of an epoxy-group-containing vinyl monomer (GMA), followed by a reaction of the epoxy group with diethylamine. Bovine serum albumin (BSA) was multilayered up to six layers by the permeation of a BSA solution through the pores of the DEA-group-containing porous membrane. A chromatogram of DL-tryptophan was obtainable by the injection of a racemic Trp solution into a BSA-multilayered membrane acting as a stationary phase. The selectivity coefficient, defined as the retention time ratio of L-Trp to D-Trp, increased with the degree of BSA multilayer binding, and remained constant irrespective of the flow rate of the mobile phase because of a negligible diffusional mass-transfer resistance.