Development And Application Of Ionic Liquid/deep Eutectic Solvent Based Novel Sample Pretreatment Technique

In order to improve the yield and quality of crops,pesticides are widely used during the growth of them.However,the excessive use of pesticides can cause environmental contamination,and further threaten human health.Therefore,in order to protect public health and safety,it is crucial to develop efficient and reliable technique for determination of pesticides in agricultural products.In this paper,five kinds of ionic liquid and deep eutectic solvent-based sample pretreatment techniques were designed and developed,they were combined with high performance liquid chromatography for analyzing triazine herbicides in different food samples.（1）Two kinds of extraction procedures,matrix solid phase dispersion and ionic liquid based hollow fiber liquid phase microextraction,were combined and applied to determine triazine herbicides in peanut sample.In this procedure,the peanut samples were firstly treated with matrix solid phase dispersion,and the analytes in the elution solvent was extracted by hollow fiber membrane whose lumen and pores were immobilized with ionic liquid[C₄mim][PF₆].The combination of the two methods successfully obtained high extraction efficiency and greatly eliminated the interferences from complex matrix samples.A series of important experimental parameters including type of absorbent and absorbent to sample ratio,type and volume of elution solvent,type of ionic liquid,salt addition and donor phase pH,agitating rate and time,amount of hollow fiber tubes were all investigated in detail.Under the optimal conditions,the developed method has the limits of detection and limits of quantification for triazine herbicides in the range of 0.05 to 1.71 ng g^-11 and1.68 to 5.71 ng g^-1.Moreover,it has the recovery in the range of 80.4-120.0%with relative standard deviations of equal or lower than 8.9%.（2）Acidic ionic liquid-based effervescence assisted dispersive liquid-liquid microextraction technique was developed for the determination of triazine herbicides in tea beverage sample.Br?nsted acidic ionic liquid[C₄mim][HSO₄]reacted with carbonate in the sample solution to produce a large amount of carbon dioxide.At this time,the ionic liquid was dispersed in the sample solution and extracted the target analytes.After the extraction,in order to separate the ionic liquid from the aqueous solution,an ionic exchange agent NH₄PF₆ was added to form hydrophobic ionic liquid[C₄mim][PF₆].Then,the ionic liquid was separated from the sample solution by means of centrifugation.Extraction parameters,including amounts of acidic ionic liquid and sodium bicarbonate,concentration of salt,pH value of the sample solution and volume of elution solvent were evaluated.Under the optimal conditions,the developed method has the limits of detection and limits of quantification for triazine herbicides in the range of 0.08-0.34 ng mL^-11 and 0.25-1.14 ng mL^-1,real sample recovery was varied from 76.3%to 135.9%with the relative standard deviations lower than 9.2%.（3）An acidic ionic liquid-based in syringe effervescence assisted dispersive liquid-liquid microextraction was designed and developed for the determination of triazine herbicides in juice sample.A large amount of carbon dioxide produced by the reaction of Br?nsted acidic ionic liquid[C₄mim][HSO₄]with the carbonate in the sample solution were applied for homogeneous dispersion of ionic liquid.Meanwhile,the hydrophobic ionic liquid[C₄mim][PF₆]who can be easily separated from the aqueous solution was formed by reacting with the ion-exchange material NH₄PF₆.Then the ionic liquid was separated from sample solution using the syringe with 0.22mm nylon membrane.The dispersion and separation procedure were carried out in the syringe,thus,the whole pretreatment procedure was completely free of any equipment.A variety of experimental conditions affecting extraction efficiency,including amount of acidic ionic liquid,amount of sodium bicarbonate,salt addition,and volume of elution solvent were carefully optimized.Under optimum conditions,limits of detection and limits of quantification of the method were 0.06 to 0.18 ng mL^-11 and 0.21 to 0.61 ng mL^-1,respectively.The recoveries obtained from real aqueous samples ranged from 80.8%to 123.5%,and the relative standard deviations were lower than 8.3%.（4）An acidic ionic liquid-based carbon nanotube enhanced effervescence assisted microextraction method was designed and developed for determination of triazine herbicides in honey sample.The extraction agents,namely carbon nanotube and ionic liquid were simultaneously dispersed into the sample solution by a large amount of carbon dioxide generated by sodium bicarbonate and Br?nsted acidic ionic liquid[C₄mim][HSO₄].It resulted in simple,quick and efficient absorption of target analytes.Meanwhile,the hydrophobic ionic liquid[C₄mim][PF₆]who can be easily separated from the aqueous solution was formed by reacting with the ion-exchange material NH₄PF₆.Then the ionic liquid and carbon nanotube were separated from sample solution by means of centrifugation.The procedure achieved a satisfactory level of dispersion of the carbon nanotubes in aqueous solution without any dispersion equipment,and the carbon nanotube greatly enhanced the extraction efficiency.The best extraction conditions were obtained by evaluating the influence of the amount of acidic ionic liquid,sodium bicarbonate and carbon nanotube,the salt addition,and volume of elution solvent.Under the optimal conditions,limits of determination and quantification of the method were varied from 1.27 to 2.76 ng g^-11 and 4.20 to 9.21 ng g^-11 respectively,recovery of the real sample were in the range of 75.8-128.9%,and the relative standard deviations were all lower than 9.7%.（5）In-situ magnetization deep eutectic solvent-based liquid phase microextraction was designed and developed for determination of triazine herbicides in rice sample.Deep eutectic solvent consisted of hydrogen bond acceptor tetrabutylammonium chloride and hydrogen bond donor ethylene glycol was used to extract target analytes in the sample.After extraction,magnetized agent iron chloride was added into the solution to in-situ form magnetic deep eutectic solvent,and then the magnetic deep eutectic solvent was isolated from the sample solution by magnetization.The method greatly simplified the form of magnetic eutectic solvent and separation procedure of target analytes.A series of parameters influencing the extraction efficiency including mass of deep eutectic solvent,molar ratio of hydrogen bond donor to hydrogen bond acceptor,amount of iron chloride,extraction time and elution solvent volume were investigated.Under optimal conditions,limits of detection and limits of quantification of the method were in the range of 1.49-3.10 ng g^-11 and 4.96-10.34 ng g^-1,recovery of the real sample varied from 77.9-117.2%,and the relative standard deviations were all lower than 9.1%.