Study Of Separation Of Extraction Phase And Its Application In Environmental And Food Analysis

The safety of the environment and food closely relates to people's health.It is very important to establish efficient and rapid sample pretreatment methods for the determination of the trace organic pollutants in the environmental and food samples.In this thesis,the environmental water and food were used as the analytical samples and the estrogens and triazines were used as the target analytes.Some new sample pretreatment methods were established and qualitative and quantitative analysis were finished by high performance liquid chromatography?HPLC?.These sample pretreatment methods have the advantages of simplicity,efficiency and environmental friendliness.Principles,development and applications of various liquid phase microextraction,solvent floation and solid phase extraction were introduced.The dispersive liquid–liquid microextraction combined with hollow fiber collection of extraction phase?DLLME-HFCEP?was first developed and applied to the extraction of estrogens in environmental water samples.1-Undecanol with relatively less volatility,less toxicity and low density was used as the extraction solvent and ethanol was used as the dispersive solvent.1-Undecanol had a high affinity for the hollow fiber membrane material.The hollow fiber bars with two ends sealed and a length of 2.7 cm were used to collect the extraction phase containing the analytes from the aqueous phase.The extraction phase containing analytes were eluted with acetonitrile from hollow fiber bars and the resulting eluate was analyzed by HPLC.Several experimental parameters,including pH of sample,the type and volume of the extraction and dispersive solvent,salt concentration,extraction time,collection bar number and collection time were optimized.The linear correlation coefficients of the working curves were greater than 0.9989,indicating a good linear relationship.The limits of detection for estriol,17?-estradiol and ethynylestradiol were 4.58,1.41 and 1.41?g L^-1,respectively.The precision of intraday and interday were 2.3-5.4%and 4.2-6.2%,respectively.This method was applied to the analysis of four real water samples.However,no target analytes were detectable in the four real water samples.The recoveries and precision of the analytes at two spiked levels were55.8-107.4%and 0.1-12.6%,respectively.In this method,the separation of the extraction phase and aqueous phase becomes easy with no need for centrifugation,refrigeration-thaw,or any special device.The hollow fiber was commercially available and the collection procedure was easy to be performed,which makes the present method have potential for wide applications.Small sizes of pores on the walls of the hollow fibers can block large molecules,which makes the present method have the potential for the treatment of complex matrices.The homogeneous ionic liquid microextraction combined with magnetical hollow fiber bar collection?HILME-MHFBC?of extraction phase was first developed and applied to the extraction of 6 triazine herbicides from water samples.First,hydrophilic ionic liquid[C₈MIM]BF₄]reacted with NH₄PF₆?anionic-pairing agent?.The resulting[C₈MIM][PF₆]microdroplets were insoluble in water and highly dispersed in solution.Due to high surface contact area,triazine targets were rapidly extracted into ionic liquid microdroplets,and then these ionic liquid droplets containing analytes were collected and separated with magnetic hollow fiber bars from the sample matrix.Due to the high viscosity of ionic liquid,its affinity to hollow fiber materials is weak.With the assistance of ultrasound,the fiber bars pores were impregnated with hydrophobic ionic liquid[C₄MIM][PF₆],and the affinity of hydrophobic ionic liquid droplets to the surface of fiber membrane is enhanced based on the principle of similar phase solubility.Some experimental parameters,including the type of ionic liquid,the ultrasonic immersion time of hollow fiber,the pH of sample solution,the volume of[C₈MIM][BF₄],the amount of ion-pairing agent NH₄PF₆,the NaCl concentration,the number of MHFB,the stirring rate,and the collection time were were optimized.The linear relationships of working curves for the target analytes were good?r>0.9983?.The detection limits of six analytes,terbumeton,ametryn,prometryn,terbutryn,trietazine,and dimethametryn were 0.48,0.15,0.15,0.14,0.35 and 0.16?g L^-1,respectively.The precision of intraday and interday were 1.3-8.0%and 2.2-3.8%,respectively.The recoveries and precision of the analytes at two spiked level were 73.4-118.5%and 0.1-9.2%,respectively.This method overcomes the disadvantage of weak affinity of high viscosity of ionic liquid to hollow fiber materials,and ionic liquid droplets were successfully collected without centrifugation,which simplified the extraction phase separation process,and further expanded the selective range of extraction solvent when hollow fiber was used as the collection material.Based on the foaming property of the honey solution,a rapid,simple,and effective method solvent floatation?SF?was developed and firstly applied to the extraction and separation of 8 triazine herbicides in honey.Ethyl acetate was used as flotation solvent and simazine was used as internal standard.The effects of some parameters,including the type and volume of extraction solvent,type of salt,amount of?NH₄?₂SO₄,pH value of sample solution,gas flow rate,and floatation time were studied.The working curves of each analytes had a good linear relationship?r>0.9996?in the concentration range of 1.56-200.00?g kg^-1.The limits of detection and quantification were 0.16-0.56?g kg^-1 and 0.52-1.86?g kg^-1,respectively.The precision of intraday and interday were 0.3-2.9%and 3.1-6.2%,respectively.The recoveries and precision at two spiked levels for analysing of five honey samples were78.2-112.9%and 0.2-9.2%,respectively.This method has the advantages of high extraction efficiency,simple phase separation and remarkable purification ability,which further expands the application scope of solvent floatation.The dynamic solid phase extraction was developed and applied to the separation of six triazine herbicides in milk samples.Macroporous resin SP850 with a porous organic skeleton structure was used as adsorbent.The analytes can be directly adsorbed and separated with SP850 SPE column with no need of protein removal in advance.The factors influencing the extraction efficiencies of the target analytes,including the type of macroporous resin,amount of resin,dilution with water,salt concentration,pH value of milk,flow rate,adsorption equilibrium time,type and volume of elution solvent,were investigated.The linear correlation coefficients of the working curves were greater than 0.9996,indicating a good linear relationship.The detection limits for atraton,desmetryn,secbumeton,ametryn,terbuthylazine and prometryn were 0.15,0.18,0.31,0.15,0.20,and 0.22?g L^-1,respectively.The precision of intraday and interday were 1.91-3.85%and 0.59-3.78%,respectively.The recoveries and RSDs at two spiked levels for milk samples were 91.5-107.8%and0.15-6.77%,respectively.This method does not need to remove the protein in advance,and the target analytes can be directly adsorbed and separated from the milk samples.The extraction was simple,the experimental procedure was simplified,the amount of organic solvent was small,and the macroporous resin can be used again and again after simple treatment.