背景:食品安全已成为公众关注的重要方面,并且有许多检测手段。液相色谱具有分离效率高、重现性好等优点,在食品安全检测中占据主导地位。然而,随着实际样品的复杂性和监测要求的增加,传统的单模色谱需要频繁的柱更换,并且不能同时在单个柱上分离不同种类的分析物,这是昂贵且耗时的。非常需要制造混合模式固定相并验证将混合模式固定相用于食品安全检查的可行性。
结果:这项工作制造了用于液相色谱的多功能固定相,以在RPLC/HILIC/IEC的混合模式下确定多种食品添加剂。合成了两种双阳离子离子液体硅烷并键合到硅胶表面。通过傅里叶变换红外光谱对功能化二氧化硅进行了表征,X射线光电子能谱,和元素分析。两个柱都提供了对6个亲水核苷的令人满意的分离性能,4疏水多环芳烃,5个阴离子获得了很大的保留重复性(RSD<0.1%)和柱效率(100330板/m)。热机械分析和线性溶剂化能关系研究了保留机理。最后,在两个制备的柱中使用较好的分离和确定蔬菜中NO2-和NO3-的含量(菠菜中最高4906mgkg-1NO3-),瓶装饮料中的防腐剂(软饮料中的180.8mgkg-1苯甲酸钠),和牛奶中的三聚氰胺,性能和回收率在96.4%至105.6%之间。
结论:这项工作开发了一种通过双阳离子离子液体制备混合模式固定相的新方案,该方案提供了出色的分离选择性。最重要的是,这项工作证明了采用混合模式固定相进行食品安全检查的优越性,这可能会在不久的将来避免高成本和频繁更换色谱柱和色谱系统。
BACKGROUND: Food safety has become an essential aspect of public concern and there are lots of detection means. Liquid chromatography plays a dominating role in food safety inspection because of its high separation efficiency and reproducibility. However, with the increasing complexity of real samples and monitoring requirements, conventional single-mode chromatography would require frequent column replacement and cannot separate different kinds of analytes on a single column simultaneously, which is costly and time-consuming. There is a great need for fabricating mixed-mode stationary phases and validating the feasibility of employing mixed-mode stationary phases for food safety inspection.
RESULTS: This work fabricated multifunctional stationary phases for liquid chromatography to determine diverse food additives under the mixed mode of RPLC/HILIC/IEC. Two dicationic ionic liquid silanes were synthesized and bonded onto the silica gel surface. The functionalized silica was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis. Both columns provide satisfactory separation performance towards 6 hydrophilic nucleosides, 4 hydrophobic polycyclic aromatic hydrocarbons, and 5 anions. Great repeatability of retention (RSD <0.1 %) and column efficiency (100330 plate/m) were obtained. Thermomechanical analysis and linear solvation energy relationship investigated the retention mechanism. Finally, the better in two prepared columns was employed to separate and determine the contents of NO2- and NO3- in vegetables(highest 4906 mg kg-1 NO3- in spinach), preservatives in bottled beverages (180.8 mg kg-1 sodium benzoate in soft drink), and melamine in milk with satisfactory performance and recovery rates ranging from 96.4 % to 105.6 %.
CONCLUSIONS: This work developed a novel scheme for preparing mixed-mode stationary phases by dicationic ionic liquid which provides great separation selectivity. Most importantly, this work proved the superiority of employing mixed-mode stationary phases for food safety inspection, which might avoid high-cost and frequent changes of columns and chromatography systems in the near future.