Preparation Of Organic Functionalized Ordered Mesoporous Silica And Determination Of Triazine Herbicides

In recent years,the problem of pesticide residues in fruits and vegetables has become increasingly serious which has caused a great threat on human health.Therefore,the determination of pesticide residues in these samples has aroused great concern.However,due to the complexity of fruit and vegetable matrix and low content of pesticide residues,analytes cannot be directly determined by the analytical instruments.Therefore,it is necessary to carry out a pretreatment procedure in advance to realize the separation and enrichment of trace targets from complex matrix.At present,common pretreatment methods include solid phase extraction?SPE?,magnetic solid phase extraction,solid phase micro-extraction,matrix solid phase dispersion and stir bar extraction,etc.The core of these methods is the adsorbent materials,therefore,the development of high-performance adsorbent material is essential.At present,common adsorbents such as CNT,C18,SiO2 and NH2 have advantages of good stability and wide application,but these adsorbents also have some drawbacks such as single adsorption mechanism and low adsorption capacity,which made them difficult to isolate trace targets from complex matrix.Mesoporous silica materials have been widely used in catalysis and adsorption fields because of their advantages such as large specific surface area,highly ordered pore channels and uniform and adjustable pore size.However,the mesoporous silica only has few functional group,which limits its further application.Besides,the modification process often requires the use of toxic volatile organic solvents or acid/base catalyst,causing some harm to human health.So the development of environmental friendly synthesis method is one of the problems to be resolved in the preparation of functionalized mesoporous silica.This research introduced two kinds of functional groups,amino group?-NH2?and n-octyl?-C₈?group,on the surface of mesoporous silica,by co-condensation and post-grafting.Thus a bi-functionalized ordered mesoporous silica was prepared,which enriched the adsorption mechanism and improved the adsorption capacity of mesoporous silica.At the same time,in the grafting process,a deep eutectic solvent?DES?was used as the reaction solvent,which developed an environmental friendly synthetic procedure and reduced the influence to human health.At last,the obtained functionalized ordered mesoporous silica was employed as the adsorbent of SPE,combining with high performance liquid chromatography to establish the determination method of triazine herbicides in watermelon.In Chapter One,the research progress of mesoporous silica was introduced,and the application of functionalized ordered mesoporous silica as SPE adsorbent was expounded.The preparation methods were summarized and optimized.The research status of DES,and discussed the feasibility of its application in the process of mesoporous silica.In Chapter Two,a C₈-amino-bifunctionalized ordered mesoporous silica?C₈-AMS?was prepared by using DES as solvent of the grafting reaction.Four parameters influencing the reaction efficiency were investigated,and the optimal conditions were obtained.The material obtained under optimal conditions was characterized.In Chapter Three,the optimized C₈-AMS was applied as SPE adsorbent to extract triazine herbicides in watermelon.The conditions of SPE procedure were optimized.By combining with high performance liquid chromatography,a new method for the determination of triazine herbicides residues from watermelon was established.