Preparation And Application Of Copper Ferrite-based Solid Phase Microextraction Fibers

Solid phase microextraction?SPME?is an environmentally friendly sample pretreatment technique which has been commonly used to analyze trace pollutants.Fiber coating is one of the most important conditions for determining the extraction efficiency of SPME.Thus a lot of attention of relative researches has been paid to the development of new fiber coatings.In this thesis,copper ferrite?CuFe₂O₄?,copper ferrite modified by titanium dioxide?TiO₂-CuFe₂O₄?,and copper ferrite modified by chitosan?CS-CuFe₂O₄?were prepared as SPME fiber coatings,respectively.Phthalate esters?PAEs?were selected as target analytes.Combining with gas chromatography,analytical methods for PAEs in aqueous samples were established.The main contents of thesis are as follows:?1?CuFe₂O₄ particles in nano scale were prepared by citrate-nitrate combustion method and characterized to observe the morphology and crystallization.The novel SPME fiber was formed by coating prepared CuFe₂O₄ on the surface of pretreated stainless steel wire,which was used as fiber substrate.The obtained fiber was then used for the determination and analysis of di-n-butyl phthalate?DBP?,benzyl butyl phthalate?BBP?,di?2-ethylhexyl?phthalate?DEHP?and di-n-octyl phthalate?DNOP?in water.Several factors on SPME procedure,including extraction time,extraction temperature,desorption time,and desorption temperature were investigated in detail.Under optimized conditions,the linear range of DBP was 1-500?g L^-1,while the linear range of BBP,DEHP,and DNOP was 1-250?g L^-1,with the correlation coefficients between 0.9854 to 0.9995.The limits of detection and the limits of quantification for all analytes were 0.12-0.40?g L^-1 and 0.40-1.33?g L^-1,respectively.The intra-day precision and the inter-day precision of single fiber were less than12.4% and 15.1%,respectively.And the fiber-to-fiber precision was less than 16.5%.Mineral water in plastic bottles were used as the real samples and none target analytes were detected from them with the established method.However,the spiked water samples offered a satisfactory range of relative recoveries of 81.1-103.7%.?2?TiO₂-CuFe₂O₄ composite with high surface area was synthesized by sol-gel method and prepared as the SPME fiber coating for detecting DBP,BBP,DEHP and DNOP in aqueous samples.The linear range of this SPME-GC method constructed in optimization conditions was 1-500?g L^-1 for DBP and BBP,while 10-500?g L^-1 for DEHP and DNOP.The corresponding correlation coefficients were in the range of0.9828-0.9969.For those PAEs,the limits of detection were from 0.17 to 2.86?g L^-1,and the limits of quantification varied from 0.57 to 9.53?g L^-1.The relative standard deviations for intra-day and inter-day of single fiber and fiber-to-fiber were 5.3-11.0%,8.2-13.2% and 9.3-16.7%,respectively.Recovery experiments for bottled mineral water of different spiked concentrations were performed with the proposed method,and relative recoveries of 77.1-125.1% were obtained.?3?Addition of chitosan during the preparation of CuFe₂O₄ was favorable to improve the dispersibility of products.The obtained CS-CuFe₂O₄ particles were coated on the treated stainless steel wire to assemble SPME fiber,which exhibited good extraction ability for four PAEs in aqueous samples.After optimizing the influencing factors of extraction efficiency,the analytical performance of the method was demonstrated to possess satisfactory linear range,detection limit and reproducibility.Among them,DBP and DEHP showed linear correlation from 1 to400?g L^-1,and linear correlation for BBP and DNOP was between 1 and 300?g L^-1,with the correlation coefficients of 0.9813-0.9947.The limits of detection and the limits of quantification for this method ranged from 0.29 to 0.47?g L^-1 and from 0.97 to 1.57?g L^-1.The repeatability for intra-day and inter-day of single fiber was8.7-13.4% and 6.3-14.5%,and for fiber-fiber was between 8.8 and 17.9%.The analytical method has been successfully applied to the detection of real water samples,with the recoveries of standard addition in the range of 85.6-110.4%.?4?The extraction ability of these fibers was compared.It was found that CS-CuFe₂O₄ fiber showed the best extraction efficiency on target analytes,then followed by TiO₂-CuFe₂O₄ fiber and CuFe₂O₄ fiber,respectively.In addition,all the performance parameters of these proposed SPME methods were equivalent to or better than those of some similar analytical methods for PAEs.