The determination of neonicotinoids in six traditional Chinese herbs using an ionic liquid-supported magnetic covalent-organic frameworks as sorbents

A novel ionic liquid-modified magnetic COFs composite with facile magnetic separation was successfully synthesized. • Multiple synergistic adsorption mechanisms for analytes were verified via theoretical calculation and characterizations. • A sensitive and robust MSPE-HPLC method with low LOD was established for neonicotinoid detection. • It was successfully applied to determine neonicotinoid in traditional Chinese medicines with ideal matrix effects. • This work broadens the application of COFs in pesticide monitoring of complex herbal matrices. In this work, an ionic liquid (PrSO 3 HMIm + PF 6 − ) was incorporated into the pore of covalent organic frameworks (COFs) to support the skeleton and further prevent collapse. The integrated PrSO 3 HMIm + PF 6 − @COFs were modified onto the Fe 3 O 4 magnetic nanoparticles, endowing the composite with convenient magnetic separation and multiple analyte-target binding capabilities. Through the theory calculation and other physical characterizations, some adsorption interactions were verified, mainly including the hydrogen bond, cationic–π, π–π, p–π, electrostatic and electron donor–acceptor interactions, and the adsorption mechanism was also discussed. Various parameters affecting the extraction efficiency were investigated, including solution pH, dosage of adsorbent, adsorption time, type of eluent, desorption time and dosage of eluent. The developed PrSO 3 HMIm + PF 6 − @COFs-MSPE-HPLC method demonstrated good linearity (R 2  ≥ 0.9903), acceptable accuracy (81.57%–119.77%), good repeatability (2.89%–5.03%), good reproducibility (3.23%–5.80%), low limits of detection (0.015–0.027 μg·L −1 ). It was used for the detection of neonicotinoids in six traditional Chinese herbs with desirable matrix effects (5.24%–19.83%). The approach has broadened the application scope of COFs in the extraction and determination of pesticides in traditional Chinese herbs. Download: Download high-res image (110KB) Download: Download full-size image