烟嘧磺隆分子印迹微球的制备及其吸附性能的考察

采用沉淀聚合法制备了烟嘧磺隆(NS)分子印迹聚合物微球(NS-MIPMs)。以甲基丙烯酸(MAA)为功能单体、三甲氧基丙烷三甲基丙烯酸酯(TRIM)为交联剂、偶氮二异丁腈(AIBN)为引发剂、氯仿为致孔剂在60 ℃下加热引发聚合。对分子印迹微球的聚合工艺进行了优化，当NS/MAA/TRIM/AIBN的物质的量比为1：4：4：1、致孔剂体积为90 mL时，制备的NS-MIPMs的吸附能力最强。利用紫外分光光度计研究了模板分子和功能单体间的作用机理。结果表明，在预聚合阶段，功能单体和模板分子间的主要作用形式是一个模板分子与一个功能单体发生作用。通过静态吸附实验及动力学吸附研究考察了NS-MIPMs的吸附性能，并结合Scatchard模型分析得到聚合物的最大结合量为11370.5 μg/g。将制备的分子印迹微球应用于固相萃取技术中，制备烟嘧磺隆分子印迹固相萃取(NS-MIPMs SPE)小柱，并对小柱进行淋洗条件的优化。同时建立了NS-MISPE-HPLC快速检测土壤中烟嘧磺隆残留量的分析方法，样品中的农药经乙腈和磷酸盐缓冲液提取，提取液经NS-MIPMs SPE小柱净化后进行HPLC分析。结果表明，烟嘧磺隆在0.01~1 mg/L范围内线性关系良好，相关系数为0.9986；添加水平为0.02~1 mg/kg时的回收率为82.2%~86.3%，相对标准偏差为1.9%~4.3%。该方法简单、高效、重现性好，可用于土壤中烟嘧磺隆的快速检测。

Preparation of nicosulfuron molecularly imprinted microspheres and research of adsorption characteristics

Molecularly imprinted microspheres (MIPMs) for binding and recognition of nicosulfuron (NS) (NS-MIPMs) were prepared by precipitation polymerization. Methacrylic acid (MAA) was used as the functional monomer, trimethylolpropane trimethacrylate (TRIM) as the linking agent, 2,2-azobisisobutyronitrile (AIBN) as the initiator and chloroform as the porogenic solvent. The preparation conditions were optimized, and MIPMs exhibited the best adsorption capacity when the molar ratio of NS/MAA/TRIM/AIBN was 1:4:4:1 and the volume of the porogenic solvent was 90 mL. An ultraviolet-visible (UV-Vis) spectrophotometer was employed to study the mechanism of the interaction between NS and MAA, and the results showed that the NS-MAA complexes of 1:1 molar ratio were obtained in the pre-polymerization phase. The rebinding capacity of MIPMs was evaluated according to adsorption kinetics and adsorption isotherm of the imprinted microspheres. The Scatchard plot revealed that the template polymer system has a two-site binding behavior and the MIPMs exhibited the maximum rebinding to NS at 11370.5 μg/g. The MIPMs were then used as adsorbents in a solid phase extraction (SPE) column and the optimum loading, washing and eluting conditions for the MIPMs were established. Additionally, a rapid method for the determination of NS residues in soil was developed using an NS-MIPMs SPE column. The analyte was extracted using acetonitrile and phosphate buffer, cleaned-up by an NS-MIPMs SPE column and analyzed by HPLC. The results showed that good linearity was observed in the range of 0.01-1 mg/L for NS, with a correlation coefficient of 0.9986. The recovery tests were performed at the spiked levels of 0.02-1 mg/kg, and the recoveries were in the range of 82.2%-86.3% with the relative standard deviations of 1.9%-4.3%. The advantages of the proposed method are that it is easy to operate, reliable and applicable to analyze the NS residues in soil samples.