Magnetic Molecularly Imprinted Polymer Based Solid-phase Extraction Coupled With Gas Chromatography-mass Spectrometry For Detection Of Atrazine

Atrazine,also known as gadolinium,is a kind of homotriazine herbicide,which is used in the cultivation of agricultural products worldwide due to its broad spectrum of herbicides,high efficiency and low toxicity.However,there is a potential carcinogenic risk of atrazine,which can enter the body through a variety of ways and cause harm.Therefore,it is of great significance to develop an efficient,sensitive and accurate Atrazine analytical method.Since the low concentration of atrazine and interfering substances,it is difficult to directly detect atrazine in the environmental water.Therefore,the sample must be separated and enriched prior to detection.Solid-phase extraction is a widely used sample preparation technique.Adsorbent is the core of this technology.Classical solid-phase extraction methods often use C18-bonded silica gel as an adsorbent,but when used in the treatment of large volumes of water samples,the operation is complicated and takes a long time,and does not possess the characteristics of high efficiency and high speed.Therefore,it is necessary to develop a new type of solid phase extraction adsorbent with specific recognition ability and rapid enrichment and separation capability.In this paper,the atrazine-imprinted magnetic nanomaterials were prepared by surface molecular imprinting technique,and its adsorption performance for atrazine was studied.Using this material as an adsorbent,a new method for the determination of trace atrazine by solid phase extraction-gas chromatography/mass spectrometry?SPE-GC/MS?was established,and its analytical performance was also explored.The method was successfully applied to detect trace atrazine in environmental waters.The main contents of this thesis include the following parts:1.The background,significance,research objectives and contents of the research work in this paper,as well as the innovative points are introduced.The commonly used analysis and detection methods for atrazine are summarized.2.The experimental instruments,reagents and research methods used in this article are introduced.3.PreparationandcharacterizationofAtrazine-imprintedmagnetic nanomaterials.Using a double-bonded magnetic mesoporous silicon composite?Fe₃O₄@mSiO₂@A171?as a carrier,atrazine as a template molecule,and itaconic acid as a functional monomer to prepare atrazine-imprinted magnetic nanomaterials through surface molecular imprinting technology.The synthesized materials were characterized by Fourier transform infrared spectrometer,scanning electron microscope,transmission electron microscope,thermogravimetric analyzer,X-ray diffractometer and vibrating sample magnetometer.After orthogonal optimization experiments,the optimal synthesis conditions for Atrazine-blotted magnetic nanomaterials were as follows:300 mg of Fe₃O₄@mSiO₂@A171 composite material,120 mg,400 mg of atrazine and itaconic acid.As we can see from the corresponding characterization analysis results,the imprinted material with atrazine as a template molecule has a uniform particle size,an average particle size of about 300 nm,a coated imprinting layer amount of about 39.5%,and a saturation magnetization of5.31 emu/g.With superparamagnetism.The Fourier transform infrared?FTIR?and X-ray diffraction?XRD?spectra of the material show the characteristic absorption peaks and diffraction peaks of the related groups,which indicates that the material has been successfully prepared.4.Adsorption Characteristics of atrazine imprinted magnetic nanomaterials.The results show that the atrazine-imprinted magnetic nanomaterials have the highest adsorption capacity for atrazine at pH=6.The increase in temperature favors the adsorption of atrazine by the magnetic nanomaterials,and the equilibriumtion has been reached within 2 hours.When the concentration of the adsorbent is 10mg/ml,the maximum adsorption of atrazine at 298K,308K and 318K is separately 8.75?mol/g,11.27?mol/g and 17.27?mol/g.The imprinting factor of atrazine-imprinted magnetic nanomaterials for atrazine,simazine,oxalazine,and prometryn,respectively reaches1.59,1.43,1.48,1.34,indicating that the material has good imprinting effect and selectivity for atrazine.After atrazine-imprinted magnetic nanomaterials were cycled5 times in the adsorption-desorption experiments,the adsorption amount of material only decreased by 10%,which indicates that the material has good repeatability.The adsorption of atrazine-imprinted magnetic nanomaterials for atrazine conforms to a pseudo-second-order kinetics model with a correlation coefficient of 0.9983,and the adsorption isotherm follows the Langmuir model.The related thermodynamic parameters?Go and?Ho show that the adsorption is spontaneously proceeded.5.A new method for the determination of trace atrazine by solid-phase extraction-gas chromatography/mass spectrometry based on atrazine-imprinted magneticnanomaterials.Thesolid-phaseextractionconditionsofthe atrazine-imprinted magnetic nanomaterials for atrazine were optimized:the material dosage was 20 mg,the sample volume was 50 ml,the extraction time was 30 min,the solution pH was 6,and the eluent was 1 ml ethanol.The analytical performance of the method was evaluated.The results showed that atrazine-imprinted magnetic nanoparticles were used as the solid phase extraction material,and the atrazine enrichment factor reached 43.The detection limit of the method was 0.015?g/L?n=3?and the limit of quantification was 0.04?g/l?n=10?.The method established in this experiment was applied to the determination of atrazine in environmental water samples.The recoveries were 87%-101%,and the relative standard deviations?n=6?were between 6%and 14%.This method has the advantages of rapid separation,enrichment,and sensitivity.