Study of the molecularly imprinted polymers for selective binding of the mono-substituted sulfonylurea herbicides

A new molecularly imprinted polymer (MIP) was synthesized for the selective extraction of mono-substituted sulfonylurea herbicides, with monosulfuron as the template and acrylamide as the functional monomer. The recognition property and affinity of the MIP for monosulfuron and its analog, monosulfuron-ester, were evaluated by equilibrium adsorption and a chromatographic study. Computer modeling, including simulated annealing and semi-empirical quantum calculation, was employed to study the recognition mechanism. The computer modeling demonstrated that monosulfuron can form multiple hydrogen bonds with methacrylic acid and acrylamide, whereas monosulfuron-ester cannot form a stable complex with these two functional monomers, which aligns with the results of the rebinding experiment. The selectivity study further demonstrated that binding sites in the MIP interact with the hydrogen in the acylamino group of mono-substituted sulfonylurea. A comparison experiment also showed that monosulfuron-imprinted MIP offers better selectivity for monosulfuron-ester than the commercial C18 high-performance liquid chromatography stationary phase material.