In situ synthesis of monolithic molecularly imprinted stationary phases for liquid chromatographic enantioseparation of dibenzoyl tartaric acid enantiomers

Abstract

A monolithic molecularly imprinted polymer (monolithic MIP) for dibenzoyl-D-tartaric acid (D-DBTA) was prepared in a stainless-steel chromatographic column tube (50 mm × 4.6 mm I.D.) as HPLC stationary phase through in situ polymerization. By optimizing polymeric and chromatographic conditions, the chiral separation of DBTA enantiomers was successfully achieved in the obtained MIP in less than 25 min with a resolution Rs = 1.25, whereas no enantioseparation effect was found on the monolithic non-imprinted polymer (NIP). Thermodynamic data of the enantioseparation were calculated. The results revealed that two different thermodynamic processes existed within the temperature range investigated, moreover, just at the transition temperature (50 °C) of the two processes, separation factor α reached its maximum. Scathcard analysis indicated that only one class of binding sites existed in the obtained MIP, with its K _d and Q _max estimated to be 5.457 × 10⁻⁴ mol L⁻¹ and 229.6 μmol g⁻¹, respectively. Nitrogen adsorption experiment proved that the prepared MIP had a large specific surface area of 105 m² g⁻¹. Scanning electron microscopy showed that large flow-through pores were present in the prepared monolith. As a consequence, the column backpressure was only 1.2 MPa with acetonitrile as mobile phase at a flow rate of 1.0 mL min⁻¹.