Isolation of L-Theanine from Plant Material using a Molecularly Imprinted Polymer.

Nylon-6 was used as a molecularly imprinted polymer (MIP). For imprinting L-theanine (5-N-ethylglutamine) in the polymer, 2.0 g of Nylon-6, 0.8 g (MIP 1), and 1.2 g (MIP 2), respectively, of L-theanine templates and 7.2 g of formic acid was used for the phase inversion process in water. The resulting polymers, including the template molecule, were washed with acetic acid solution to extract the template from the polymers. The polymers were investigated as solid phase extraction (SPE) sorbents for the cleanup of water extracts of green tea. Various amounts of the template in the polymerization mixture had no influence on sorptive properties of MIPs in the range under study. Water was found as a suitable solvent for sample loading. The selective binding capacity of MIPs was 3.49 µg/1 g MIP. Water with addition of acetic acid (2% by volume) was used as an elution solvent. The recovery of the MISPE procedure was 87.8%±5.5%. [ABSTRACT FROM AUTHOR]