Based On KIT-6 Material Magnetic Solid Phase Extraction Of Typical Pesticides In Environmental Water Samples

China is a big country in the production and use of farm chemicals,among which pesticide is the most popular.It plays a great role in increasing agricultural production and solving the problem of human food shortage.However,the abuse of pesticides may also lead to ecological destruction.Among them,trace pesticide residues in water can pose a serious threat to water environment and even terrestrial biological system through a variety of migration and transformation ways.Therefore,the detection of pesticide residues in environmental water samples is imperative.First of all,sample pretreatment methods are needed to enrich these residues,among which,magnetic solid phase extraction has been widely applied due to its high efficiency,short timecost,easy operation and many other advantages.The core of the method is the selection of appropriate adsorbents.Mesoporous silica KIT-6 has special structures,which has a good prospect in this field.In this paper,two typical pesticides?pyrethroids and neonicotinoids?were selected as the target analytes.The magnetic composites based on KIT-6 were prepared and characterized.They were then used for magnetic solid phase extraction of corresponding pesticides coupled with high performance liquid chromatography.Various external factors affecting the process were investigated.Under the optimized conditions,the method was applied to the analysis of environmental water samples.1.Preparation of magnetic composites based on KIT-6.?1?Fe₃O₄@SiO₂@KIT-6 magnetic composite was synthesized using P123 and n-Bu OH as template,tetraethoxysilane as silicon source.?2?Fe₃O₄@SiO₂@KIT-6 magnetic composites with different pore size were synthesized by changing the hydrothermal synthesis temperature.?3?The amino functionalized Fe₃O₄@SiO₂@KIT-6 magnetic composite material?Fe₃O₄@SiO₂@KIT-6-NH₂?was synthesized with 3-aminopropyl triethoxysilane?APTES?as the amination reagent.?4?The carboxyl functionalized Fe₃O₄@SiO₂@KIT-6 magnetic composite material?Fe₃O₄@SiO₂@KIT-6-COOH?was synthesized with 2-cyanoethyl triethoxysilane?CTES?as carboxylation reagent.2.The morphology,functional groups,elements,thermal stability,crystal shape,pore structure,magnetic property and so on of materials were characterized by transmission electron microscope?TEM?,scanning electron microscope?SEM?,fourier infrared spectrometer?FT-IR?,thermogravimetric analyzer?TG?,X-ray powder diffractometer?XRD?,N₂ adsorption and desorption instrument?BET?,X-ray photoelectron spectroscopy?XPS?and vibration sample magnetometer?VSM?.3.Fenpropathrin?Fenp?,lambda-cyhalothrin?Lam-cyh?,S-fenvalerate?S-fenv?,bifenthrin?Bif?,deltamethrin?Del?,cis-permethrin?cis-Per?,trans-permethrin?trans-Per?,nitenpyram?Nit?,clothianidin?Clo?and imidacloprid?Imi?were selected as target pesticides.A variety of parameters influencing magnetic solid phase extraction process including adsorption time,elution solvent,solution p H,salinity,enrichment factor and the recyle of composites were investigated.4.The limit of detections?LODs?,linearity,repeatability and sensitivity of the method were determined and verified.The adsorption mechanism between materials and analytes was preliminarily discussed based on the kinetic analysis of the adsorption process.5.The prepared nanocomposites were applied to the analysis and detection of environmental water samples respectively.In the spiked environmental water samples,the nanocomposites obtained a good recovery for the related pesticides,with the values higher than 85.1%and the relative standard deviation less than 9.9%.Compared with the researches reported,this method has a comparable or better reliability.