Highly efficient chiral separation of amlodipine enantiomers via triple recognition hollow fiber membrane extraction

•Robust and stable molecularly imprinted hollow fiber membranes were prepared.•Triple recognition based on imprinted membrane and dual chiral additives was achieved.•A selectivity factor for enantioseparation of (S)-amlodipine reached 1.98.•The cross-flow experiment provided a potential large-scale production process.

In this study, a triple recognition chiral extraction process has been developed to separate (S)-amlodipine from racemic raw medicine, based on the combination of molecularly imprinted hollow fiber membrane and cross-flow biphasic recognition extraction. The chiral separation process was operated in a dismountable hollow fiber module coated with molecularly imprinted polymer, and the cross-flow extraction was applied with d-tartaric acid in feed phase and sulfobutyl ether-β-cyclodextrin in stripping phase. The synergistic effect of molecularly imprinted polymer and dual chiral additives was investigated, and excellent enantioseparation ability with a selectivity factor of 1.98 was obtained. Mathematical model of S/R = 0.598e0.150NTU for racemic amlodipine separation by molecularly imprinted hollow fiber membrane extraction was established. The optical purity for amlodipine is up to 90% when 4 hollow fiber membrane modules of 25 cm in length in series are used. The triple recognition process strongly enhanced the separation selectivity; therefore it may bring about the potentially application for large-scale production of pure enantiomeric compound.