Enantioseparation of D,L-phenylalanine by molecularly imprinted polymer particles filled capillary electrochromatography

The chromatographic properties of molecularly imprinted polymer filled capillary electrochromatography (CEC) have been studied. The network polymers were prepared using L-phenylalanine anilide (L-pheAN) or L-phenylalanine as print molecules. Methacrylic acid was used as functional monomer, such that the acid function of monomer interacts ionically with the amine function and via hydrogen bonding with the carboxyl group of the print molecules. Ethylene glycol dimethacrylate was used as cross-linker and the reaction initiator was alpha, alpha'-azobis(isobutyronitrile). The obtained polymers were ground and sieved to particles<10 mu m for filling into capillary for CEC and <30 mu m for packing into high performance chromatographic columns. The separations of D,L-phenylalanine by using the molecularly imprinted polymers against L-pheAN and L-phenylalanine were compared. It was interesting to find that the resolution of D,L-phenylalanine using L-pheAN printed polymer was higher than that using L-phenylalanine printed polymer. The selected polymers obtained were tested in CEC. Some aromatic amino acids, such as D,L-phenylalycine, D,L-tyrosine etc., could be separated to some extent. This method demonstrated that the molecularly imprinted polymer can also be used in CEC for the separation of enantiomers. The peak shape and the resolution of D,L-phenylalanine by this proposed method were batter than those by the HPLC method.