Ionic liquid functionalized magnetic microporous organic network for efficient extraction of phenoxyacetic acid herbicides from vegetables.

Herein, a novel ionic liquid doped magnetic microporous organic network (IL-MMON) with abundant electrostatic and ion exchange sites was synthesized for the first time for highly efficient and selective magnetic solid-phase extraction (MSPE) of polar phenoxycarboxylic acid herbicides (PCAs) from complex vegetable samples. The prepared IL-MMON exhibits large specific surface area, rapid magnetic response, good stability and ample PCAs binding sites. The extraction efficiencies can be reasonably regulated by tuning the doping ratios of IL. The established method has wide linear ranges (1-1000 μg L-1), low limits of detection (0.3-1.3 μg L-1), large enrichment factors (94.6-99.9), less adsorbent consumption (3 mg), short extraction time (8 min), good recovery (80.9-105.8 %), and insignificant matrix effect (89.2-108.5 %). The experimental and DFT analyses revealed extraction mechanisms include electrostatic attraction, ion exchange, and π-π interactions. This study shows considerable potential of IL-MMON and may open up a new way for synthesizing IL-MMON in sample pretreatment.