Preparation Of Mixed-Mode Magnetic Nano-Adsorbent And Its Application In The Enrichment And Detection Of Trace Hazardous Substances

Accurate high-throughput and high sensitivity analysis of trace toxic and hazardous substances in complex samples such as biology and the environment has always been a frontier research topic in analytical chemistry.Especially,the development and application of new materials used for enrichment of trace or ultra-trace multi-target substances in complex matrices still face challenges.Magnetic solid phase extraction(MSPE)as a promising extraction method posses a lot of advantages,such as high surface area,facile surface modification,limited diffusion resistance,and easily recycle using an external magnetic field.In the paper,three functionalized materials with novel structures,rich recognition sites and excellent adsorption capacity are selected to build three kinds of magnetic nano-adsorbents with stable structure,good dispersibility and high adsorption capacity by adopting appropriate linking strategies.They are applied as sorbent for fast,simple and highly selective capture of trace multi-targets in urine and environmental water.The main contents are as follows:(1)A comprehensive review of research progress of magnetic solid phase extraction related to the research of this dissertation.(2)A novel dual-shell Tp BD(a kind of COFs)coated magnetic nanospheres(Tp BD MNS)was prepared and characterized by using infrared spectra,thermogravimetric analysis,X-ray powder diffraction,nitrogen sorption,scanning electron microscopy,transmission electron microscopic,magnetization curves and Energy-dispersive X-ray spectroscopy.Its adsorption performance to fourteen heterocyclic aromatic amines was also studied.Quantum chemistry theory calculation was conducted to directly and quantifiably describe the multiple interactions,including ?-?,hydrogen bonding,cation-?,static electricity and ion-exchange,between Tp BD and heterocyclic aromatic amines.Based on the prepared magnetic sorbent,a new method coupled with the ultra performance liquid chromatography-tandem mass spectrometer detection(MSPE-UPLC-MS/MS)was developed and used for the simultaneous detection of fourteen HAAs in non-smokers' and smokers' urine samples.Under the optimized conditions,the recovery range from 95.4% to 129.3%,the LOD for the 14 HAAs ranged from 0.14 to 0.46 pg/m L.After being washed with acetonitrile and water successively,the collected sorbents can be easily recycled and reused for five times without any significant difference in performance.The t-test method and data statistics analysis were used to analyse the determination results of urinary HAAs.Based on the results,the relation between cigarette smoking with different tar yields and urinary HAAs content was evaluated.The findings provide a new material and method for revealing the relationship between smoking and health.(3)The prepared TPBD functionalized magnetic sorbent was used for the determination of trace morphine and its metabolites in mouse urine.The main influencing factors of MSPE,including the adsorbent amount,eluent type,elution volume,adsorption time,desorption time were optimized.By combining with UPLC-MS/MS technology,a novel MSPE-UPLC-MS/MS method was constructed and used for the determination of trace morphine,morphine-6-glucuronide(M6G)and morphine-3-glucuronide(M3G)in mouse urine.The LOD for MOR,M3 G and M6 G ranged from 0.16-0.53 pg/m L.The recovery of the developed method is between 88.3% and 93.7%,with RSDs < 5%,which indicates that the established method has high accuracy and good stability.On this basis,the pharmacokinetics of morphine and its metabolites in mouse urine after the administration of a certain amount of morphine by intravenous injection were investigated.Based on the obtained results,we plot the curve of morphine and its metabolites over time,which provides an important basis for clinical treatment and drug regulation.(4)A novel dual-shell magnetic nanosorbent coated with a cationic covalent organic framework,containing ethidium bromide(EB),(EB-DS MNS)are easily prepared and characterized by using infrared spectra,thermogravimetric analysis,X-ray powder diffraction,nitrogen sorption,scanning electron microscopy,transmission electron microscopic,magnetization curves and Energy-dispersive X-ray spectroscopy.This is the first time that a cationic crystalline framework with high thermal and chemical stability has been used for magnetic solid phase extraction(MSPE),which shows high selective capacity to nine hydroxylated polycyclic aromatic hydrocarbons(OH-PAHs).Quantum chemistry theory calculations demonstrated the existence of multiple interactions between EB-COF and OH-PAHs.Coupled with HPLC-FLD,an MSPE-HPLC-FLD method based on the prepared magnetic sorbent was established and used for the determination of 9 OH-PAHs in non-smokers and smokers smoking cigarettes with different tar yields.All the OH-PAH analyses present good linearities in the range of 0.1-100 ng/m L,with R2 > 0.9965.The LOD for 9 OH-PAHs ranged from 0.0030 to 0.0096 ng/m L and the LOQ ranged from 0.096 to 0.030 ng/m L.The recoveries of 9 OH-PAHs ranged from 93.3 to 121.3% with an RSD ranging from 0.47 to 3.53%.The relevance of the urinary OH-PAHs contents among non-smokers and cigarette smoker smoking cigarettes with different tar yields was revealed based on the detection results using the developed method,which provide a reference for the health of smokers.(5)A dispersive magnetic SPE(d-MNSPE)strategy with the simultaneous extraction and stepwise elution(SESE)procedure was developed based on the tetraazacalix[2]arene[2]triazine(TCT)coated magnetic nanoparticular(TCT MNP)adsorbent,which was used to simultaneous extraction and characterization of diverse kinds of multi-target analytes.TCT assembles two benzene rings and two triazines with nitrogen cross-bridging links,which exhibits a unique structural framework and versatile recognition features based on the multiple recognition sites,such as ? electron stacking,charge transfer,hydrogen bonding and ion-exchange.TCT MNPs shows strong adsorption towards PAHs,nitroaromatics and heavy metal ions,which ensure the success of simultaneous extraction and stepwise elution with different eluent.Trace probes in tap water,river water and lake water were determined with very low detection limits,in the range 0.09-0.15 pg/m L for PAHs,6-11 pg/m L for nitroaromatics and 17-53 pg/m L based on the d-MNSPE SESE strategy coupled with the commonly used HPLC-fluorescence detection,HPLC-UV detection and atomic absorption spectrometry.The method provided high recovery(> 90%)and good precision(relative standard deviations,RSD < 10%).The determination of trace PAHs in urine samples from smokers and non-smokers was successfully carried out with this method,and the relation between smoker and PAHs exposure level was also evaluated.All the results implied that the versatile TCT MNPs and the robust method together represent a significant potential application in the analysis of body fluids and disease markers.