磁性共价有机骨架材料选择性分离食品中无机砷及其机理研究

Food is an important source of inorganic arsenic exposure, it is crucial important to establish a convenient and quick arsenic species separation method to improve the detection efficiency of inorganic arsenic in food and thus to insure the food safety. Magnetic solid phase extraction (MSPE) has advantages such as convenient and quick in the separation of arsenic species. However, MSPE faced drawbacks such as low selectivity and adsorption capacity of magnetic materials, which is a problem to be solved urgently. Covalent organic frameworks(COFs) is an ideal adsorbents with high selectivity because of its characteristics such as high surface area, controllable structure and easy to modify. The applicant has found that the post modified COFs showed high selectivity and large adsorption capacity for inorganic arsenic. Based on these, we proposed to fabricate magnetic COFs for selective separation of inorganic arsenic from food. The project would fabricate magnetic COFs with core-shell structure using layer-by-layer and one-pot method, then the magnetic COFs would be functioned using post modification method. Then, the structure-activity relationship between magnetic COFs and inorganic arsenic, and the separation mechanism could be studied. Finally, MSPE system could be established for selective separation of inorganic arsenic from food based on magnetic COFs. The results of the project could provide theoretical and technical support not only for the fabrication of selective adsorbent for inorganic arsenic, but also for the separation and detection of inorganic arsenic in food.

食品是无机砷暴露的重要途径，建立一种简便、快速的砷形态分离方法对于提升无机砷检测效率进而确保食品安全具有重要意义。磁性固相萃取在砷形态分离中具有简便、快速的优势，但目前存在磁性吸附材料选择性低、吸附容量小的缺点，是亟待解决的关键问题。共价有机骨架材料（COFs）具有比表面积大、结构可控及易修饰等特点，申请人前期通过后修饰制备对无机砷有高选择性、吸附容量大的COFs，因此本项目拟在此基础上构建磁性COFs并选择性分离食品中无机砷。本项目拟采用层层自组装等方法构建核壳结构磁性COFs并通过后修饰使其功能化；研究磁性COFs的微观结构与其吸附选择性及吸附容量之间的构效关系，阐明磁性COFs对无机砷的选择性吸附机理；基于磁性COFs构建选择性分离食品中无机砷的磁性固相萃取体系。本项目的开展将为无机砷选择性吸附材料的构建以及选择性分离食品中无机砷方面提供重要的理论基础与技术支撑。

砷（Arsenic, As）的生物毒性不仅与其总量有关，更取决于其存在形态，有机砷毒性较小、甚至无毒，而无机砷（包括AsⅢ和AsⅤ）则公认具有高毒性和致癌性。食物是无机砷暴露的重要途径，无机砷膳食暴露对人体健康的影响已收到广泛重视，目前食品中无机砷残留是我国食品安全重点监控对象之一。由于食品中除含无机砷外，还含有一定量的有机砷，必须对食品中不同形态砷化合物进行有效分离才能避免或减少有机砷对无机砷分析结果的干扰。显然，建立简单、快速的选择性分离无机砷方法对于提升无机砷检测效率进而确保食品安全具有重要意义。本项目基于共价有机骨架材料（Covalent Organic Frameworks，COFs）具有组成和结构丰富多样、密度轻、比表面积大、结构稳定以及易修饰等特点，制备了对无机砷吸附有强选择性和高吸附容量的磁性COFs和COFs纳米纤维两种复合材料，并基于COFs复合材料构建了食品中无机砷的磁性固相萃取和管尖固相萃取两种方法，实现食品中无机砷快速、高效、低成本的分离分析方法。本项目的开展将为无机砷选择性吸附材料的构建以及选择性分离食品中无机砷方面提供重要的理论基础与技术支撑。项目结果表明，磁性COFs对无机砷具有良好的吸附选择性，实验建立的无机砷分析检测方法的As(V)线性范围是0.018 μg/L～30 μg/L，相关系数为0.9992，方法检出限为0.018 μg/L，方法精密度RSD值小于1%，利用该方法对绿茶等样品中的无机砷进行了测定，加标回收率在88%-117%之间。基于COFs纳米纤维和管尖固相萃取建立的食品中无机砷检测方法的线性范围为0.018 μg/L～30 μg/L，相关系数高于0.999，精密度RSD值小于5%，检出限为0.018 μg/L，样品加标回收率为80%～100%