Preparation Of Zirconium Metal-Organic Framework Coated Magnetic Materials For The Extractions Of Small-Molecule Compounds

Natural small-molecule compounds are one of the important sources for drug discovery,and their separation and analysis are of great significance.However,natural products have complex components and the matrix intereference is serious.The coexisting interferents may interact with target compounds and will affect the sensitivity and accuracy of analysis.Therefore,it is necessary to use appropriate sample pretreatment methods to enrich,purify and separate the target analyte from the complex matrix,so as to make the qualitative and quantitative analysis of the target analytes more accurate.In this thesis,based on the magnetic solid phase extraction（MSPE）technology,different metal organic frameworks（MOFs）functionalized magnetic sorbents were prepared for the enrichment of natural small-molecule compounds.The prepared magnetic nanoparticles（MNPs）were applied to enrich the small-molecule compounds in different traditional Chinese medicines.The thesis mainly contains five chapters,including three chapters of experimental research.The first chapter is the literature review.Firstly,sample pretreatment methods for natural product analysis was described briefly.Secondly,the advantages and research progress of MSPE in sample pretreatment were introduce,and the characteristics of the MOF modified magnetic sorbent and its application in MSPE were summarized.Finally,the main content and significance of this thesis were put forward.The second chapter is to prepare UiO-66@PA@PEI@Fe₃O₄magnetic sorbent for the enrichment of berberine in Rhizoma Coptidis and Cortex Phellodendri.Firstly,the optimal synthesis conditions are determined by optimizing the reaction temperature,reaction time and the content of formic acid during the process of material synthesis.Secondly,the physicochemical properties of the prepared MNPs were investigated by several characterization techniques.At the same time,the factors affecting the extraction and elution efficiency of berberine were optimized and the reusability and stability of the prepared MNPs were also investigated.Then,the molecular docking software and adsorption isotherm models were used to investigate the adsorption mechanism of the prepared MNPs.The results showed that the adsorption of berberine by the prepared MNPs was mainly accomplished by hydrophobic interaction,with the highest adsorption capacity of 50.01mg/g,and the adsorption type was single-layer adsorption.Finally,the prepared MNPs combined with HPLC method were applied to extract and analyze the berberine in Rhizoma Coptidis and Cortex Phellodendri.The recovery were 76.1%and 71.6%,respectively.The results showed that UiO-66@PA@PEI@Fe₃O₄ has good stability,large adsorption capacity and low detection limit,which can be used for the extraction and enrichment of berberine in complex matrices.The third chapter is to prepare NH₂-UiO-66@PDA@Fe₃O₄ magnetic sorbent for the extraction of neochlorogenic acid,chlorogenic acid and cryptochlorogenic acid in Lonicerae Japonicae Flos.The acetic acid content were optimized for the synthesis of material and the prepared MNPs were characterized by several techniques.Then,the factors affecting the extraction and elution efficiency of three analytes were optimized and the established method was validated.The reusability and stability of the prepared MNPs were also investigated.And then,the Langmuir and Freundlich adsorption isotherm models were used to investigate the adsorption mechanism of prepared MNPs.The highest adsorption capacity of the material for neochlorogenic acid,chlorogenic acid and cryptochlorogenic acid were 11.93mg/g,24.42mg/g and 18.75 mg/g,respectively.In addition,the R²of Langmuir isotherm model was larger,which could infer that the adsorption of the three analytes by the sorbent belongs to the single-layer adsorption.Finally,the prepared MNPs combined with HPLC method were applied to the extraction and analysis of neochlorogenic acid,chlorogenic acid and cryptochlorogenic acid in Lonicerae Japonicae Flos,and the recovery reached77.6%-98.7%.The results showed that NH₂-UiO-66@PDA@Fe₃O₄ has good reusability,good stability,and low detection limit,which has the potential for the enrichment of three phenolic acids in complex matrices.The fourth chapter is to prepare Co-NH₂-UiO-66@PDA@Fe₃O₄ magnetic sorbent for the extraction of puerarin,3-hydroxypuerarin and puerarin apioside from Radix Puerariae.Firstly,different ratios（Zr:Co=1:0,1:1,1:4,1:8）doping were optimized for the synthesis of material and the prepared MNPs were characterizatied by several characterization techniques.Then,the factors affecting the extraction and elution efficiency of three analytes were optimized and the established method was validated.The reusability and stability of the prepared MNPs were also investigated.The linear correlation coefficients（R²）were all higher than 0.9997 and the limit of detection was7.81-15.12ng/mL.Finally,the prepared MNPs combined with HPLC method were applied to the extraction and analysis of puerarin,3-hydroxypuerarin and puerarin apioside in Radix Puerariae,and the recovery was 45.0%-97.0%.The results showed that Co-NH₂-UiO-66@PDA@Fe₃O₄ has the advantages of good stability and low detection limit,and has the potential to be applied in the extract of puerarin and puerarin apioside in complex matrices.The fifth chapter is the summary and perspective.In this thesis,combined the advantages of easy separation of magnetic sorbents and the easy modification and good stability of zirconium metal organic framework（Zr-MOF）,three different Zr-MOF modified magnetic sorbents were prepared.The prepared materials combined with the HPLC method were applied to the extraction and analysis of small-molecule compounds in natural products.The results of this thesis provide a simple and effective sample pretreatment method for the analysis of natural products.At the same time,this thesis expands the applitions of MOFs in the extraction of small-molecule compounds of natural products.