Pickering双乳液法制备分子印迹聚合物分离分析玉米中的硝磺草酮

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

该文采用Pickering双乳液法,以硝磺草酮为模板分子、甲基丙烯酸甲酯为功能单体、木质素为稳定粒子制备分子印迹聚合物,并对其进行傅里叶红外光谱、扫描电镜、X射线衍射与接触角表征,同时探究了该聚合物对硝磺草酮的静态吸附、动态吸附和选择性吸附。Scatchard分析表明:合成的聚合物对硝磺草酮的结合方式有两种,最大表观吸附量(Q_(max))和平衡离解常数(Kd)分别为Q_(max1)=32.31 mg/g,K_(d1)=116.28 mg/L;Q_(max2)=89.99 mg/g,K_(d2)=413.22 mg/L。动力学测定结果显示:该聚合物对硝磺草酮的吸附符合准二级动力学模型。将制备得到的分子印迹聚合物作为基质固相分散的分散剂萃取分离玉米中的硝磺草酮。最佳萃取条件为分子印迹聚合物与样品的质量比3∶2;研磨时间10 min,淋洗剂2 mL 20%甲醇水溶液,洗脱剂5 mL 5%乙酸乙腈。最佳条件下,硝磺草酮的检出限为0.018μg/g,回收率为97.0%~98.4%,相对标准偏差(RSD)为0.70%~5.6%。该研究分析时间短、有机溶剂用量少,且提高了选择性和分析效率。

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(Q_(max))and equilibrium dissociation constant(K_(d))were calculated as follows:Q_(max1)=32.31 mg/g,K_(d1)=116.28 mg/L,Q_(max2)=89.99 mg/g and K_(d2)=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:the mass ratio of molecularly imprinted polymer to sample was 3∶2,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 0.018μg/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.