A molecularly imprinted polymer for microextraction by packed sorbent of sulfonylureas herbicides from corn samples

A molecularly imprinted polymer (MIP) was synthesized and assessed as a selective extraction phase in the microextraction by packed sorbent (MEPS) of sulfonylureas herbicides (SUHs) - Thifensulfuron, Chlorosulfuron, Tribenuron, and Bensulfuron - from grounded corn samples. Bensulfuron was employed as the template for the MIP preparation. MIP particles were chemically and structurally characterized. Distribution (Kd), selectivity (k), and relative selectivity (k') coefficients were estimated using binary mixtures of bensulfuron/betazon and bensulfuron/prometon. The most significant parameters affecting the MEPS performance were systematically studied in univariate and multivariate experiments. Analyses were performed by liquid chromatography coupled to time-of-flight mass spectrometry (LC-ToF). Under selected conditions, the developed MIP-MEPS-LC-ToF method demonstrated suitable analytical confidence and reliability. Determination coefficients (r2) higher than 0.9940, and limits of detection (LODs) of 2.5 mu g kg-1 were obtained. Intra- and interday precision was lower than 14.2%, and accuracy ranged between 89.6% and 113.6%. The synthesized MIP demonstrated enhanced selectivity and higher SUHs uptake capability compared to the non-imprinted polymer (NIP) and tested commercial sorbents. Besides, the method is a cheap, feasible, and environmentally friendly analytical tool. A single MEPS device packed with 1.0 mg of MIP was reused more than 180 times without loss in its extraction capabilities.