具有优异选择性的磁性膨润土复合材料的制备及其对水中痕量生物毒素的萃取

Recently, several modifications of solid phase extraction (SPE) are exploited, most being based on miniaturization and automation of various stages of the SPE. Particularly noteworthy is magnetic solid phase extraction (MSPE). However, the reported MSPE sorbents, which present low extraction yield and poor selectivity for bioactive contaminants in water. And upon this, the multifunctional magnetic bentonite molecularly imprinted nanomaterials with high selectivity are prepared and used as the sorbents of MSPE for microcystins (MCs). Then, a novel method of MSPE combined with ultra-high performance liquid chromatography (UPLC) for determination of trace amounts of MCs in water samples was developed. The MSPE sorbent was simple in preparation and low cost, and the developed MSPE-UPLC method was suitable for sensitive determination of MCs in water samples. Structure characterization and surface characteristic of the magnetic sorbent will be investigated particularly; adsorption and desorption behavior of MCs on the magnetic nanomaterials will be evaluated systemically. Furthermore, the research will also focus on the clarification of adsorption mechanism for the magnetic nanomaterials acting on MCs. The results of this project will provide the theoretical principle for development of novel functionalized extraction materials. The work will also extend the application of magnetic nanomaterials in environmental and biological analysis.

近年来，基于取样装置小型化及自动化的发展需要，在传统固相萃取技术(SPE)基础上发展起来的磁性固相萃取技术(MSPE)引起了人们的广泛关注。对水中生物污染物富集效率低、选择性差是MSPE吸附剂普遍存在的问题。据此，本项目拟制备出对水中生物污染物具有选择性的功能化磁性膨润土分子印迹复合材料，用于生物毒素微囊藻毒素(MCs)的高效萃取，并与超高效液相色谱(UPLC)技术相结合，建立对水样中痕量MCs检测的新方法。这种新型的磁性复合材料具有制备方法简单、原料成本低的优势，以其作为MSPE的固相萃取材料，可以显著提高UPLC对MCs的检出限。本项目将详细表征磁性材料的结构和表面性质，系统研究影响萃取MCs的相关因素，进一步揭示磁性复合材料对MCs的吸附机理。此研究将为新型萃取材料的开发奠定理论基础，同时也将拓展磁性纳米复合材料在环境分析及生物分析等领域的应用。

膨润土具有比表面积大、易于功能化修饰等优点，其在溶液中以悬浊液的形式存在，限制了其在样品前处理领域中的应用。为了解决膨润土固液分离难的问题，并提高其对微囊藻毒素MC-LR的选择性吸附能力，通过一步溶剂热法在无机柱撑膨润土表面修饰Fe3O4纳米粒子。制备得到的磁性膨润土材料Fe3O4@Al-B的饱和磁化强度为36.2 emu/g，比表面积为110 m2/g。由Langmuir等温吸附方程式拟合得到Fe3O4@Al-B对MC-LR的最大吸附容量为161.3 mg/g，该磁性材料可用于溶液中MC-LR的选择性萃取。进一步以磁性膨润土为基板，选择微囊藻毒素的MC-LR构型为模板分子，以多巴胺为交联剂和功能单体，制备得到表面分子印迹材料Fe3O4@B-MIPs。不加入模板分子制得的磁性吸附剂无法萃取溶液中的MCs，而Fe3O4@B-MIPs对溶液中的MCs具有选择性萃取能力。在最佳条件下，建立了基于该磁性材料的用于环境水中MCs分析的MSPE-UPLC分析方法，该方法的定量限、检出限均低于WHO限定的饮用水中MCs允许的最高浓度（1μg/L）。以水中的抗生素类污染物为研究目标，制备了对氟喹诺酮类及四环素类抗生素具有选择性萃取能力的磁性纳米微球Fe3O4-Cys@MIL125-NH2、Fe3O4@SiO2@FeO。建立了基于上述磁性材料的、用于分析水中抗生素类污染物的MSPE-UPLC/TUV分析方法。本实验拓展了环境友好的膨润土及磁性纳米材料在样品前处理领域的应用，为环境水样中痕量MCs、抗生素的精准测定提供了便捷的分析方法。