Ionic liquid-mediated molecularly imprinted solid-phase extraction coupled with gas chromatography-electron capture detector for rapid screening of dicofol in vegetables

New ionic liquid-mediated molecularly imprinted polymers (IL-MIPs) were prepared by precipitation polymerization using 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM+PF6-) as the auxiliary solvent, (alpha-chloro-DDT as the dummy template, and they were successfully applied as the sorbents of solid-phase extraction (SPE) for rapid screening of dicofol from cabbage, tomato, and carrot samples. The IL-MIPs were characterized by FTIR, FE-SEM, static adsorption and chromatographic evaluation, and the results revealed that the IL-MIPs had higher adsorption capacity and selectivity to dicofol in aqueous solution than that of ionic liquid-mediated non-imprinted polymers (IL-NIPS) and non-imprinted polymers (NIPs). Under the optimized conditions, the IL-MIPs-SPE-GC method offered good linearity (0.4-40.0 ng g(-1), r(2) = 0.9995) and the average recoveries of dicofol at three spiked levels were in a range of 84.6-104.1% (n =3) with RSD <= 7.6%. The proposed method obviously improved the selectivity and purification effect, and eliminated the effect of template leakage on dicofol quantitative analysis. (C) 2013 Elsevier B.V. All rights reserved.