Molecularly Imprinted Polymers for the Enantioseparation of Methylephedrine Chiral Drug

In this study molecular imprinting technology was employed to prepare a specific affinity sorbent for the resolution of Methylephedrine, a chiral drug. The molecularly imprinted polymer (MIP) was prepared by non-covalent molecular imprinting with either (+) or (-)-Methylephedrine ((R*,S*)-2-(methylamino)-1phenylpropan-1-ol) as the template. Methacrylic acid and ethylene glycol di-methacrylate were copolymerized in the presence of the template molecule. The bulk polymerization was carried out in chloroform with 2,2’azobisisobutyronitrile as the initiator, at 5°C and under UV radiation. The resulting MIP was ground into powders, which were slurry packed into analytical columns. After removal of template molecules, the MIPpacked columns were found to be effective for the resolution of (±)-Methylephedrine racemates. The separation factor for the enantiomers ranged between 1.3 and 2.1 when the column was packed with MIP prepared with (+)-Methylephedrine as the template. A separation factor ranging from 1.3 to 2.6 could be achieved from the column packed with MIP, prepared with (-)-Methylephedrine as the template. Although the separation factor was higher with that previously obtained from reversed-phase column chromatography following derivatization with a chiral agent, elution peaks were broader due to the heterogeneity of binding sites on MIP particles and the possible non-specific interaction.