磁性分子印迹聚合物萃取/高效液相色谱检测蔬菜中的灭多威

Determination of Methomyl in Vegetables by Magnetic Molecularly Imprinted Polymer Extraction/High Performance Liquid Chromatography

以磁性分子印迹聚合物为吸附剂,建立了蔬菜中灭多威的快速、选择性分析方法。以灭多威为模板分子,甲基丙烯酸为功能单体,二甲基丙烯酸乙二醇酯为交联剂,Fe3O4为磁性组分制备该聚合物。通过红外光谱、扫描电镜以及综合物性测量仪对合成的聚合物进行表征。Scatchard分析表明磁性分子印迹聚合物对灭多威有两种结合方式,最大表观吸附量(Qmax)和平衡离解常数(Kd)分别为Qmax1=0.053 04 mmol/g,Kd1=0.314 35 mmol/L;Qmax2=0.130 51 mmol/g,Kd2=1.921 22 mmol/L。动力学结果显示该聚合物对灭多威的吸附符合准二级动力学模型。与其它物质相比,制备的聚合物对灭多威具有高选择性识别性能。考察了萃取溶剂、聚合物用量、萃取时间、振荡速度、解析溶剂对灭多威回收率的影响。采用高效液相色谱对灭多威进行检测,检出限为0.012 mg/kg,RSD为2.2%～6.1%,加标回收率为86%～94%。该方法应用于检测甘蓝、小白菜、西红柿、黄瓜和辣椒中的灭多威。结果显示在西红柿样品中检出有灭多威,其含量为1.135 mg/kg。与传统的方法相比,该方法快速、有效,在食品农药残留的分析中具有很好的前景。

A rapid and selective method was successfully developed using magnetic molecularly imprinted polymer（MMIP） as sorbent for the extraction of methomyl from vegetable samples. The MMIP was synthesized using methomyl as template molecule, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as crosslinking agent and Fe_3O_4 magnetite as magnetic component. The MMIP was characterized by Fourier transform infrared spectra, scanning electron microscope and physical property measurement system. Seatchard plot analysis revealed that two kinds of different binding sites existed in MMIP, in which the maximum amount of apparent binding and dissociation constant of binding sites were as follows： Q_max1 =0.053 04 mmol/g, K_d1 = 0.314 35 mmol/L; Q_max2=0. 130 51 mmol./g, K_d2 = 1. 921 22 mmol/L. The kinetic property of MMIP was well fitted to the pseudo-second-order equation. The result indicated that MMIP had high selectivity towards meth- omyl over reference compound. The effects of extraction solvent, MMIP amount, extraction time, shaking rate, desorption solvent on recoveries of methomyl were investigated. Under the optimal con- ditions, the limit of detection of methomyl was 0. 012 mg/kg, the spiked recoveries of methomyl were in the range of 86% - 94% with relative standard deviations （RSDs） of 2.2% - 6. 1% . The method was applied in the determination of methomyl in vegetable samples, including cabbage, pakchoi, to- mato, cucumber and pepper, in which, methomyl was detected in the tomato sample with concentration of 1.135mg/kg.Compared with the traditional method,the proposed method is rapid and effective,and is promising for the analysis of pesticide residues in food samples.