Preparation of molecularly imprinted cross-linked chitosan/glutaraldehyde resin for enantioselective separation of l-glutamic acid

In the present study, separation of l-glutamic acid from dilute aqueous solution by solid-phase extraction based on molecular imprinting technique using cross-linked chitosan/glutaraldehyde resin was investigated. l-Glutamic acid imprinted cross-linked chitosan (LGIC) was prepared by cross-linking of chitosan by glutaraldehyde cross-linker, in the presence of l-glutamic acid. Non-imprinted cross-linked chitosan (NIC) as control was also prepared by the same procedure in the absence of template molecules. The morphological structures of both LGIC and NIC were examined by scanning electron microscope (SEM). LGIC particles were applied to determine the optimum operational condition for l-glutamic acid separation from dilute aqueous solution. In adsorption step, optimum pH and retention time were 5.5 and 100 min, while corresponding values in extraction step were 2.5 and 60 min, respectively. The adsorption isotherms indicated that the maximum adsorption capacities of l- and d-glutamic acid on LGIC were 42 ± 0.8 and 26 ± 1.2 mg/g, respectively, while in case of NIC, both l- and d-glutamic acid present the same maximum adsorption capacity 7 ± 0.6 mg/g, which confirm that the molecular imprinting technique creates an enantioselectivity of LGIC toward l-glutamic acid. In addition, chiral resolution of l-, d-glutamic acid racemic mixture was carried out using column of LGIC.