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 mu g kg(-1), the determination limits of chlorimuron-ethyl, nicosulfuron, thifensulfuron-methyl and chlorsulfuron were 0.075, 0.069, 0.083, and 0.105 mu g kg(-1), respectively. The relative standard deviations were less than 5.5%.