To explore electrodialysis for purification of negatively charged large organic molecules (e.g., amino acids and medicine), water-swollen formyl methyl pyridinium-immobilized polyvinyl alcohol (PVA-FP) anion-exchange membranes were prepared and characterized in terms of their electrochemical properties. The PVA-FP membranes exhibited low electrical resistance (1.0-3.0 Omega cm(2)), high swelling properties (water content ratio, 0.62-0.73), and reasonable transport number ((t) over bar_ > 0.96 for Cl-). For glutamic acid solutions, the electrical resistance of the PVA-FP membrane was low (1.0-3.0 Omega cm(2)) in a wide pH range, with no membrane fouling. Since the resonance effect of quaternary aromatic ammonium contributed to the structural stability of the PVA-FP membrane, the water-splitting with the PVA-FP membrane was approximately one order of magnitude lower than that with a commercial ion-exchange membrane at a same current density. (c) 2004 Elsevier B.V. All rights reserved.