Separation and Analysis of Mesotrione in Maize Using a Molecularly Imprinted Polymer Preparated by Pickering Double Emulsion Method

KeyWord:Pickering double emulsion  mesotrione  lignin  molecularly imprinted polymers  matrix solid-phase dispersion

Abstract:

      In this study£¬a molecularly imprinted polymer was prepared by Pickering double emulsion method using mesotrione as template molecule£¬methyl methacrylate as functional monomer£¬divinylbenzene as coupling agent and lignin as a stable particle£®The polymer was characterized by Fourier transform infrared spectroscopy£¬scanning electronic microscopy£¬X-ray diffraction and contact angle£®Moreover£¬the static adsorption£¬dynamic adsorption and selective adsorption of this polymer toward mesotrione were discussed£®Results of Scatchard analysis showed that there existed two kinds of binding sites for mesotrione£¬the values of apparent maximum absorption capacity£¨Qmax£© and equilibrium dissociation constant£¨Kd£© were calculated as follows£ºQmax1 = 32.31 mg/g£¬Kd1 = 116.28 mg/L£¬Qmax2 = 89.99 mg/g and Kd2 = 413.22 mg/L£®The adsorptive dynamics results showed that the adsorption of the polymer toward mesotrione accorded with quasi-secondary dynamics model£®The prepared molecularly imprinted polymer was used as the dispersant of matrix solid-phase dispersion for separation of nitrosulfuron in maize£®The optimal extraction conditions were as below£ºthe mass ratio of molecularly imprinted polymer to sample was 3¡Ã2£¬the grinding time was 10 min£¬washing solvent was 2 mL 20% methanol solution£¬and 5 mL 5% acetic acid£­acetonitrile was used as elution solvent. Under the optimum conditions£¬the limit of detection for mesotrione was 0.018 ¦Ìg/g£®The recoveries ranged from 97.0% to 98.4%£¬with relative standard deviations£¨RSDs£© of 0.70%£­5.6%£®This method could reduce the analysis time and the use of organic solvents£¬and improve the selectivity and analysis efficiency£®