Direct enantioseparation of adrenergic drugs via thin-layer chromatography using molecularly imprinted polymers.

Molecularly imprinted polymers (MIPs) of (-)-pseudoephedrine and (-)-norephedrine were prepared to use as chiral stationary phases (CSPs) in thin layer chromatography (TLC). The resolution of the enantiomers of adrenergic drugs, including pseudoephedrine, ephedrine, norephedrine, and epinephrine were investigated on these CSPs. In preparation of MIPs, two monomers: (1) methacrylic acid and (2) itaconic acid were employed as functional monomers. Mobile phase system of either methanol or acetonitrile was used and the effects of acetic acid content of the mobile phases were also investigated. The best resolution was achieved for enantioseparation of norephedrine on plates based on MIP of (-)-norephedrine using itaconic acid as functional monomer (alpha = 5.1) in mobile phase 1% acetic acid in methanol. Moreover, these MIPs were able to resolve the racemates of compounds whose structures corresponded to print molecule. The results obtained showed that TLC based on MIPs could succeed the direct separation of enantiomers of adrenergic drugs as a method of separation. The method offers a rapid, sensitive and reliable method for quality control of optically active compounds.