The Research On Solid-phase Extraction Of Proteins And Dyes By Ionic Liquid-modified Magnetic Composites

Magnetic solid-phase extraction（MSPE）is a kind of improved sample pretreatment technology based on traditional solid phase extraction.It uses materials with magnetism as extractant and possesses advantages of simple operation,rapid magnetic separation,easy to be automated and so forth.Ionic liquid is a type of salt with low melting point,which consists of organic cation and organic or inorganic anion.It is of many excellent advantages,such as negligible vapor pressure,high thermal and chemical stability,non-volatility,designable structure and function,ect..It can bring many benefits to employ magnetic materials modified with ionic liquid as extractants in MSPE.On the one hand,it’s good for the environment to use ionic liquids to replace volatile organic solvents.On the other hand,it can overcome drawbacks of traditional extraction technology like tedious operation,low extraction efficiency and long time-consumption to use MSPE.Therefore,it provides new ideas for modern extraction technology to combine ionic liquids with MSPE.In this study,several kinds of ionic liquids and polymeric ionic liquids were synthesized and used for the extraction of proteases and dye coupled with MSPE.The main contents of this work are as follows:（1）Magnetic solid-phase extraction for trypsin based on dianionic amino acid ionic liquid-coated PEG 4000 modified Fe₃O₄ nanocompositeA novel magnetic extractant,PEG 4000 modified Fe₃O₄ nanomaterial that coated with dianionic amino acid ionic liquid（Fe₃O₄@PEG@DAAAIL）,was successfully synthesized and characterized by X-ray diffraction（XRD）,transmission electron microscope（TEM）,vibrating sample magnetometer（VSM）,fourier transform infrared spectrometry（FT-IR）,thermal gravimetric analysis（TGA）and zeta potentials.Subsequently,trypsin（Try）was selected as the target analyte to study the extraction behavior of Fe₃O₄@PEG@DAAAIL in MSPE.The concentrations of Try in the supernatant were detected by UV–vis spectrophotometer at 278 nm.Compared with extractant without modification by IL and other three kinds of extractants modified with IL,the extraction ability of Fe₃O₄@PEG@DAAAIL for Try turned out to be better.Furthermore,single factor experiments were carried out to investigate the influence of extraction time and temperature,initial Try concentration,the value of pH and ionic strength.Under the optimal extraction condition,the extraction capacity for Try could reach up to 718.73 mg/g.The extracted Try could be eluted by phosphate buffer solution with pH value of 2.0,and the elution rate was 91.48%.The repeatability experiment proved that the extraction capacity for Try kept over 90%of initial extraction capacity after eight recycles.According to the result of activity analysis experiment,the activity of Try after extraction retained 92.29%of initial activity,verifying the biocompatibility of the prepared extractant.Under the optimum condition,the analysis of real sample was carried out.It was proved that Fe₃O₄@PEG@DAAAIL could successfully extract Try from borvine pancreas crude extract.Methodological research certified the proposed method with satisfactory precision,repeatabilityandstability.TheMSPEmethodbasedon Fe₃O₄@PEG@DAAAIL provides a new idea for the extraction of proteins.（2）Magnetic solid-phase extraction forα-chymotrypsin based on carboxymethylcellulose sodium modified Fe₃O₄ nanocomposite coated with porous polymeric dianionic ionic liquidA novel magnetic extractant,carboxymethylcellulose sodium modified Fe₃O₄nanocompositecoatedwithporouspolymericdianionicionicliquid（Fe₃O₄@CMC@PPDIL）,was synthesized and characterized by VSM,TGA,TEM,XRD,FT-IR and zeta potentials.Afterwards,?-chymotrypsin（?-Chy）was selected as the target analyte to study the extraction behavior of Fe₃O₄@CMC@PPDIL in MSPE.The concentrations of?-Chy in the supernatant were detected by UV–vis spectrophotometer at 278 nm.Compared with extractant without modification by IL and other two kinds of extractants modified with polymeric ionic liquid（PIL）,t he extraction ability of Fe₃O₄@CMC@PPDIL for?-Chy turned out to be better.Besides,single factor experiments were carried out to investigate the influence of initial?-Chy concentration,extraction time and temperature,the value of pH and ionic strength.Under the optimum condition,the extraction capacity of Fe₃O₄@CMC@PPDIL for?-Chy could reach up to 122.91 mg/g.The extracted?-Chy could be eluted by phosphate buffer solution with pH value of 2.0,and the elution rate was 88.32%.The repeatability experiment proved that the extraction capacity for?-Chy kept 81.51%of initial extraction capacity after seven recycles.According to the result of activity analysis experiment,the activity of?-Chy after extraction retained 91.05%of initial activity,verifying the biocompatibility of the prepared extractant.Under the optimum condition,the analysis of real sample was carried out.It was proved that Fe₃O₄@CMC@PPDIL could successfully extract?-Chy from porcine pancreas crude extract.Methodological research certified the proposed method with satisfactory precision,repeatability and stability.All of above proves the potential value of the MSPE method based on Fe₃O₄@CMC@PPDIL in the extraction of?-Chy or other analytes from biomass.（3）Magnetic solid-phase extraction for methyl blue based on magnetic multi-walled carbon nanotubes modified with polymeric dicationic ionic liquidA novel magnetic extractant,magnetic multi-walled carbon nanotubes modified with polymeric dicationic ionic liquid（m-MWCNT@DCPIL）,was synthesized and characterized by XRD,VSM,TGA,TEM,FT-IR and zeta potentials.The prepared m-MWCNT@DCPIL was used as the extractant for methyl blue coupled with MSPE.The concentrations of methyl blue（MB）in the supernatant were detected by UV–vis spectrophotometer at 627 nm.Compared with other extractants prepared in this work,m-MWCNT@DCPIL possesses the best extraction property for methyl blue.The extraction conditions,including the concentration of methyl blue,extraction time and temperature,pH value and ionic strength,were optimized by single factor experiments.Under the optimal extraction condition,the extraction efficiency for methyl blue turned out to be 98.25%.The repeatabilit y experiment proved that the extraction efficiency for methyl blue kept at 94%after seven recycles.Under the optimum condition,the analysis of real sample was carried out.It proves that m-MWCNT@DCPIL could successfully extract methyl blue from waste wa ter.Methodological research certified the proposed method with satisfactory precision,repeatability and stability.The MSPE method based on m-MWCNT@DCPIL provides a new idea for the environmental analysis.