Monolithic molecularly imprinted polymer for sulfamethoxazole and molecular recognition properties in aqueous mobile phase

A monolithic molecularly imprinted polymer (monolithic MIP) for sulfamethoxazole (SMO) was prepared by in situ polymerization method as the HPLC stationary phase. By optimizing the polymerization conditions, the monolithic MIP showed highly specific recognition for the template SMO over its three structurally related analogs. As shown by SEM and the pore size distribution profile, the resultant MIP monolith showed a main pore diameter of 594 nm and a large specific surface area of 124 m² g⁻¹, this allowed the mobile phase to flow through the column with low backpressure. Furthermore, the recognition abilities of the monolithic MIP in aqueous and organic media were studied. The results exhibited that the monolithic MIP possessed excellent recognition ability in aqueous media. Hydrophobic interactions, in addition to shape recognition, were the dominant effect for recognition in the mobile phase with high water content. Moreover, the binding sites and the dissociation constant were also determined by frontal chromatography as 122 μmol g⁻¹ and 1.88 × 10⁻⁵ mol L⁻¹, respectively, which demonstrated that the obtained SMO-MIP monolith had a high binding capacity and strong affinity ability to the template molecule. Furthermore, the resultant SMO-MIP monolith was used as HPLC column directly to determine the SMO contents in three kinds of pharmaceutical tablets with the optimized aqueous mobile phase.