Rapid, low temperature synthesis of molecularly imprinted covalent organic frameworks for the highly selective extraction of cyano pyrethroids from plant samples.

New imine-linked molecularly imprinted covalent organic frameworks (MICOFs) were successfully prepared, using fenvalerate as the dummy template. Schiff base reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-triformylphloroglucinol was rapidly achieved at room temperature, using Sc(OTf)3 as the catalyst. The surface groups and morphologies of MICOFs were assessed by Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area analysis, and scanning electron microscopy. The MICOFs exhibited high selectivity toward four structurally similar cyano pyrethroids, including fenvalerate, flucythrinate, ß-cyfluthrin and λ-cyhalothrin. A method based on solid phase extraction using MICOFs coupled to high performance liquid chromatography was established for the determination of cyano pyrethroids in plant samples. Linearity in the range 0.1-200 ng g-1, with correlation coefficients of 0.9981-0.9993, was obtained for the four cyano pyrethroids. Detection limits and quantification limits were in the range 0.011-0.018 ng g-1 and 0.036-0.060 ng g-1, respectively. Recoveries at three spiked levels ranged from 94.3% to 102.7%. The developed method is thus a promising technique for the selective extraction of cyano pyrethroids from complex matrices.

Selective solid phase extraction of chloroacetamide herbicides from environmental water samples by amphiphilic magnetic molecularly imprinted polymers.

In this study, a novel amphiphilic magnetic molecularly imprinted polymers (MMIPs) have been prepared by using Fe3O4 microspheres as the magnetic core, 4-vinyl pyridine (4-VP) and alkenyl glycosides glucose (AGG) as functional co-monomers. Fe3O4 microspheres were directly encapsulated by the polymer without any surface modification in the distillation-precipitation polymerization. The morphology and composition of MMIPs were characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Binding property and magnetic separation ability were systematically investigated through the equilibrium binding experiments. The feasibility of magnetic molecular imprinted solid phase extraction (MMISPE) was investigated for the selective enrichment of chloroacetamide herbicides from environmental water samples. The developed MMISPE-HPLC method exhibited good linearity (0.1-200µgL-1), low limit of detection (0.03-0.06µgL-1), and good precision (RSD<7%) under the optimized conditions. The introduced MMISPE-HPLC method was successfully used to analyze chloroacetamide herbicides in environmental water samples. Spiked chloroacetamide herbicides recoveries in three water samples ranged from 82.1% to 102.9%. These results indicated that amphiphilic MMIPs were the promising sorbents for the selective enrichment of chloroacetamide herbicides at trace levels from real environmental water samples.