Multiple monolithic fibers modified with a molecularly imprinted polymer for solid phase microextraction of sulfonylurea herbicides based on boron-nitrogen interaction.

This study describes a highly selective, sensitive and eco-friendly method for the determination of sulfonylurea herbicides (SUHs) in soya milk and grape juice samples. The SUHs can be extracted selectively and effectively by using molecularly imprinted multiple monolithic fibers (BNMIP/MMF) that undergo boron-nitrogen interactions with the SUHs. The sorbent can be fabricated by in-situ polymerization using triflusulfuron-methyl (TSM) as the template, and 1-vinyl-3-octylimidazolium tetrafluoroborate as the functional monomer. Results indicate that the boron-nitrogen interaction plays an important role in the selective extraction of TSM and its structural analogues. The recognition coefficient of BNMIP/MMF for TSM was as high as 8.1. Following elution with the binary solution of acetonitrile/formic acid (99.5/0.5), the SUHs were quantified by HPLC with diode array detection. Under the most favorable conditions, the limits of detection (S/N = 3) for SUHs in spiked soya milk and grape juice samples ranged between 14-58 ng·L-1 and 46-91 ng·L-1, respectively. Additional merits include high selectivity, wide linear ranges, good precision, low consumptions of sample and organic solvent. In the analysis of SUHs in real samples, the recoveries at different fortified concentrations varied from 75.2 to 102%, and the relative standard deviations (n = 3) were in the range of 1.8-9.2%. Graphical abstract Schematic presentation of the effect of the concentration of tetrafluoroborate on the extraction selectivity of sulfonylurea herbicides (SUHs) by molecularly imprinted multiple monolithic fibers (BNMIP/MMF).