| With the rapid development of economy and the continuous income improvement for residents,food and environmental safety issues have caused widespread concern in China.Meanwhile,establishing of more strict guidelines and improvement of the analytical ability and efficiency of themselves become the serious parts of routine works of authorities such as administrations of food and drug,and environmental protection.Rapid,economic and high throughput techniques for pretreatment of food and environmental samples with complex matrix provide vital technical support for food and environmental safety.In this dissertation,several new type of solid phase extraction sorbents based on ionic liquids,molecular imprinted polymers,noble metal nanoparticles and hydrotalcites,with their corresponding packaging and applying methods,were synthesized and designed to realize the efficient extraction,enrichment and clean-up of triazine herbicide residues in foods and volatile organic compounds in environmental sludges.High performance liquid chromatography(HPLC)and gas chromatography-mass spectrometry(GC-MS)were employed for the performance evaluation of the developed sorbents.The main work and achievements of this dissertation are outlined as follows.1.Molecular imprinting polymers(MIPs)with highly selective extraction capacity were synthesized by using atrazine as template molecules.Routine syringe filters were employed as the sorbent containers to fabricate a low-cost and easy-to-use device for solid phase extraction(SPE).Solutions of samples as well as solvents for washing and eluting were injected into the sorbent containers to carry out adsorption,clean-up and desorption for targets.Extraction,enrichment and purification of triazine herbicides in Radix Paeoniae Alba(RPA)were performed with the developed SPE device.Effects of several experimental parameters on the extraction performance,including the type and amount of extraction solvent,the type of of the washingsolvent and elution solvent,were investigated by HPLC.The detection limits(LODs)of the proposed method for five triazine herbicides were ranged from 0.09-0.39 ng g-1,which were lower than the maximum residue limits(MRLs)of triazine herbicides established by various official organizations.Results of comparison between the proposed method and other conventional sample pretreatment methods indicate that high selectivity,less organic solvents and low cost are the major advantages of the proposed method,which make it suitable for the quality control of agricultural and food products.2.Based on the good chemical design ability of ionic liquids(ILs),a new type of supported ionic liquids(SILs)was designed and synthesized by covalently bonding1-carboxyethyl-3-methylimidazolium chloride on surfaces of glass slides.Simultaneous extraction of seven triazine herbicides in rice samples was performed by the synthesized SILs-based SPE sorbent.Effects of the type of extraction solvent,extraction time,type and volume of loading solvent,and type of elution solvent on extraction efficiencies were investigated.Under the optimal experimental conditions,LODs of seven triazine herbicides in rice samples obtained by HPLC ranged from3.16 to 5.42 ng g-1,which were lower than the MRLs of triazine herbicides in food established by various official organizations.The extraction recoveries of seven triazine herbicides at the spiked concentrations of 0.15 and 0.45 ?g g-1 in real samples were in the range of 82.47-104.21%.By utilizing the loading and the supporting capacities of the glass slides,the adsorption and desorption procedure of the the proposed SILs-based SPE method were simplified,and the operation time was reduced obviously than conventional SPE methods.By fully taking advantages of their excellent physic-chemical properties,including large specific surface area,high porosity,non-toxicity,and ease of preparation,zinc oxide nanoparticles(Zn O NPs)were employed as the solid support of an IL,1-carboxyethyl-3-methylimidazolium chloride,to prepare a novel SILs-based SPE sorbent.Five kinds of triazine herbicides in corns were extracted using a laboratory-made SPE equipment consisting of a vacuum pump and array of syringe barrels,followed by determination with HPLC.Several experimental parameters affecting the extraction efficiencies were studied,including volume of extraction solvent,extraction time,type of extraction solvent and elution solvent,amount of sorbent,and volume of the elution solvent.LODs and extraction recoveries of five triazine herbicides obtained under optimal experimental conditions were0.71-1.08 ng g-1 and 85.85-103.42%,respectively.The synthesized SILs not only possess excellent extraction performance and reusability,but also are more eco-friendly and easy-to-fabricate compared with other common SPE sorbents,indicating the potential applications in the future development of sample pretreatment techniques.3.Spherical gold nanoparticles(Au NPs)possess large surface area,high stability toward aqueous and organic solutions,and good selectivity towards targets consisting of sulfur,nitrogen and oxygen groups via the formation of selective covalent bonds or strong electrostatic interactions.The porous structure and nanosheets of hydrotalcites-layered double hydroxides(NLDHs)also provide large surface area and good chemical modifiability.Therefore,a novel hybrid nanomaterial was synthesized by immobilizing Au NPs onto nanosheets of Mg/Al NLDHs via Au-O bonds and was employed as the microextraction of triazine herbicides from maize.By using the synthesized nanohybrids and an organic filter head as the sorbent and the container respectively,the semi-automated microextraction by packed sorbent(MEPS)was realized with the help of a precision injection pump.The collected eluting solution was concentrated and injected directly into HPLC for determination without further filtration.The effects of experimental parameters such as volume of Au/NLDHs nanohybrids,type,flow rate and volume of wahsing and elution solvent on extraction efficiencies were explored.The detection limits(LODs)of four triazine herbicides were in the range of 0.035-0.108 ng g-1.Compared with routine SPE methods,the volumes of organic solvents as well as the operating time for washing and eluting processes were reduced significantly by the proposed semi-automated method.Moreover,the Au/NLDHs nanohybrids can also be applied to extract other analytes containing functional groups which can interact with gold in other complicated matrix samples.Inspired by the high extraction performance of Au/NLDHs hybrids,another hybrid material using NLDHs as substrate,polyvinyl chloride(PVC)as adhesive and polyvinylpyrrolidone(PVP)as modifier was prepared.After coated on SPME Arrow,the prepared hybrid material was applied as the SPME sorbent to extract the volatile organic compounds(VOCs)in sewage sludge.Extraction performance of the prepared hybrid material was evaluated by GC-MS.Ultra-pure water samples spiked with five kinds of VOCs(allyl methyl sulfide,methyl propyl sulfide,3-pentanone,2-butanone and methyl isobutyl ketone)were used to optimize experimental conditions forextraction.Under the optimal conditions,NLDHs/PVC/PVP SPME Arrow exhibited better extraction efficiency than commercial SPME Arrows.LODs for five kinds of VOCs were obtained in the range of 0.7-2.3 ng m L-1.The fabricated NLDHs/PVP/PVC SPME Arrow was successfully applied to the extraction of VOCs in real sludge samples.Analytical results obtained by GC-MS showed that 2-butanone and methyl isobutyl ketone were positively detected in these samples at the concentrations of 50.7 and 47.7 ng g-1,respectively. |
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