The Application Research Of Magnetic Solid Phase Extraction-chromatography Technique In The Analysis Of Food And Environmental Fields

With the rapid development of economical society and the continuous enrichment of human material life,some problems such as environmental pollution and food society followed by frequently.They affect human health and life seriously,and have become two international social issues all over the world.Thus,the powerful supervision of environmental and food become an urgent task at present.However,due to lots of troubles such as extremely complex matrix,low levels of harmful substances,and some interference in the environmental and food samples,it is difficult to take analysis by instrument directly.So the samples must be pretreated to achieve the preconcentration of target analyte by special techniques.Among all of the separation and enrichment techniques,magnetic solid phase extraction has attracted extensive attentions because of several advantages,including simple operation,high efficiency,friendly to environment and easy to realize automation.In this paper,some novel magnetic nanomaterials were synthesized and applied to magnetic solid phase extraction as nano-adsorbents coupled with high performance liquid chromatography and gas chromatography as tools for the determination of polycyclic aromatic hydrocarbons（PAHs）in coffee and tea samples,sulfonamides（SAs）and quinolones（QNs）in environmental water samples,caffeine in beverage samples.The contents of this paper are as follows:1.The recent development of magnetic solid phase extraction was briefly introduced.Simultaneously,the theory of magnetic solid phase extraction,the structure and practical applications of functional magnetic nanparticles were also summarized.And several unique advantages of magnetic solid phase extraction were reviewed in analytical field by comparison with other traditional extraction techniques.At last,the significance and main content of the study were presented.2.This study reports the synthesis of a benign nano-adsorbent based on an ionic liquid of immobilized Fe₃O₄@ 3-（Trimethoxysilyl）propyl methacrylate@ionic liquid magnetic nanoparticles（Fe₃O₄@MPS@PIL NPs）.This material was applied to the magnetic solid phase extraction of seven heavy molecular weight PAHs from coffee and tea samples for highperformance liquid chromatography coupled with fluorescence detection.The effects of various parameters of the analytical method were investigated,including p H,sorbent amount,desorption solvent,desorption volume,and extraction and desorption time.Under the optimized conditions,good linearities were obtained,with correlation coefficients（R2）between 0.9987 and 0.9998.The detection limits of the proposed method were in the range of 0.1^-10 ng·L^-1.The spiked recoveries of the seven PAHs in coffee and tea samples ranged from 87.5% to 104.5%,with RSDs of less than 3.7%.In addition,a satisfactory reproducibility was achieved,with intra-and inter-day precisions with RSDs of less than 3.1% and 3.8%,respectively.3.In this study,the magnetic materials Fe₃O₄@MPS@PIL NPs were synthesized and utilized as potential adsorbents further application.First,these nanoparticles were applied to the analysis of SAs and QNs present in different water samples using magnetic solid phase extraction and high-performance liquid chromatography.Under optimized conditions,the developed method showed excellent detection sensitivity,with limits of detection（S/N =3）and quantification limits（S/N = 10）within 0.2–1.0 and 0.8–3.4 μg/L,respectively.The spiked recoveries of the SAs and QNs in environmental water samples ranged from 83.5 to 103.0%,with RSDs of less than 4.5%.In addition,the adsorbents effectively removed sulfamethoxazole and ofloxacin present in existing aquatic environments.The adsorption kinetics and isotherms of sulfamethoxazole and ofloxacin on the magnetic adsorbents were studied to assess removal performance.The results indicate that the adsorption process follows a pseudo-second-order mechanism,which reveals that the sorption mechanism is the rate-limiting step and produces high qmax values（sulfamethoxazole = 70.35 mg/g and ofloxacin = 48.95 mg/g）,thus demonstrating the enormous adsorption capacity of these magnetic adsorbents.4.A high selective and sensitive pre-treatment method for the determination of caffeine from beverage samples based on magnetic molecularly imprinted solid-phase extraction（MMISPE）was developed.The magnetic molecularly imprinted polymers（MIPs）were synthesized using theobromine as the template and ionic liquid as polymerized monomer,with high adsorption capacity and selectivity for caffeine.The MMISPE procedure was developed for the purification and enrichment of caffeine from four drink samples prior to gas chromatography-flame ionization detector（GC-FID）analysis.The limit of detection of the developed MMISPE-GC-FID method was 0.05 μg·m L–1.Spiked recoveries of caffeine in four different beverage samples（Coca cola,Pespsi cola,Red Bull and Recca 6 hours）were 103.1%,96.1%,98.6% and 97.8%,respectively.