Determination of Sulfonylurea Herbicides in Grain Samples by Matrix Solid-Phase Dispersion with Mesoporous Structured Molecularly Imprinted Polymer

A method for determination of sulfonylurea herbicides (SUHs) in grain was developed by using mesoporous structured molecularly imprinted polymers (M-MIPs) as adsorbents of matrix solid-phase dispersion (MSPD) extraction, coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). In this method, M-MIPs were synthesized by selecting chlorimuron-ethyl as template molecule, cetyltrimethylammonium bromide as mesoporous structure directing agent, 3-aminopropyltriethoxysilane as functional monomer, and tetraethyl orthosilicate as crosslinker. Then, M-MIPs were characterized by diverse instrumental techniques, absorption characteristics of M-MIPs were studied, and the experimental conditions for the MSPD extraction were optimized. MSPD enabled extraction and clean-up steps to be completed simultaneously. The M-MIPs with mesoporous structure improved detection selectivity, increased adsorptive capacity, and accelerated adsorption rate. Under the best conditions, excellent linearity of SUHs was obtained in the range of 0.25–25 μg kg−1, the determination limits of chlorimuron-ethyl, nicosulfuron, thifensulfuron-methyl and chlorsulfuron were 0.075, 0.069, 0.083, and 0.105 μg kg−1, respectively. The relative standard deviations were less than 5.5%.