Preparation Of MOFs Magnetic Nanomaterials And Its Application In Detection Of Estrogens And Plant Growth Regulators In Food Samples

Food safety is of great significance to protect people’s health.However,sample preparation is one of the important steps in the food analysis process,which directly affects the accuracy and reliability of test results.In recent years,magnetic solid phase extraction（MSPE）has developed rapidly as a new solid phase extraction method using magnetic or magnetizable materials as adsorbents.Metal organic frameworks（MOFs）,as a new class of microporous materials,have excellent performance.This work is based on MOFs selecting MIL-53（Al）-NH₂ to prepare a new magnetic nanocomposite Fe₃O₄@SiO₂@MIL-53（Al）-NH_2.and using it as an MSPE adsorbent in combination with High performance liquid chromatography-diode array detection（HPLC-DAD）to detect estrogens and plant growth regulators in food samples.In Chapter 1,It introduces the significance of the detection of estrogens and plant growth regulators in food,as well as high performance liquid chromatography,and also briefly introduces sample preparation techniques.It focuses on the principle,research progress,influencing factors and optimization of MSPE and the research progress and types of MOFs.In addition,the purpose and main content of the research of this thesis are put forward.In Chapter 2,A new magnetic nanocomposite Fe₃O₄@SiO₂@MIL-53（Al）-NH₂ based on MOFs（MIL-53（Al）-NH₂）was prepared.It was characterized by Fourier transform infrared spectroscopy,transmission electron microscope,X-ray photoelectron spectroscopy,X-ray diffraction,and Brunner-Emmet-Teller,and the adsorption mechanism of the material was deduced from the structural characteristics.In Chapter 3,Fe₃O₄@SiO₂@MIL-53（Al）-NH₂ was used as the adsorbent for MSPE for the extraction and enrichment of six estrogens.At the same time,the experimental conditions such as extraction time,pH,desorption solvent and volume,desorption time and salt concentration were optimized.Based on the optimal conditions,a method was developed for the determination of estrogen in milk and beef samples by combining Fe₃O₄@SiO₂@MIL-53（Al）-NH₂ as a MSPE adsorbent with HPLC-DAD.The results showed that the detection limit range of this method was 0.09μg/L（DES）⁰.72μg/L（E₁）.The spiked recoveries of 6 estrogens in milk and beef samples were 82.6%¹16.1%,79.1%¹18.0%.This method has the advantages of low detection limit,good extraction efficiency,wide linear range,etc.It has a good application in the analysis of estrogens in milk and beef,and shows a good development prospect in the detection of estrogens in food samples.In Chapter 4,Fe₃O₄@SiO₂@MIL-53（Al）-NH₂ was used as the adsorbent for MSPE to extract six plant growth regulators.By optimizing the experimental conditions such as extraction time,pH,desorption solvent and volume,desorption time and salt concentration,the best extraction conditions for MSPE were obtained.This method has achieved good performance in the extraction of plant growth regulators,and has a good application prospect in the detection of plant growth regulators in food samples.