Research On Ionic Liquids Microextraction Of Triazine And Sulfonylurea Herbicides In Food

Dispersive liquid-liquid microextraction(DLLME)technique is widely used in the field of sample pretreatment because of its simple operation,low cost,low reagent consumption,high recovery and enrichment efficiency.However,some toxic,flammable and volatile organic solvents are usually used as extraction solvents of DLLME.It is harmful to the environment and the health of the experimental operators.Therefore,it is important to develop a green and safe extraction solvent for DLLME.Ionic liquids(ILs)are"green solvents",which are composed of anions and cations.ILs with different physicochemical properties and selectivity can be obtained by changing the types of anions and cations.In addition,they have the advantages of low vapor pressure,eco-friendliness and high stability.In this study,ionic liquid-based supramolecular solvents dispersive liquid-liquid microextraction(SUPRAS-DLLME)and dispersive liquid-liquid microextraction coupled with dispersive solid phase extraction(DLLME-DSPE)were developed and applied to the separation and enrichment of triazine herbicides in tea samples and sulfonylurea herbicides in soymilk samples.Firstly,the mechanism,dispersion approach,type of extraction solvents and application of DLLME are introduced.In addition,the type,physicochemical properties and analytical applications of ILs are also summarized.After that,a novel SUPRAS based on surface active ionic liquid(IL)was prepared and used as an extraction solvent for the extraction of four triazine herbicides in tea samples.High performance liquid chromatography was applied to the separation and determination of four triazine herbicides.The formation mechanism of SUPRAS was studied by phase diagram.The microstructure and physicochemical properties of the SUPRAS were characterized by TEM,SEM,TGA,densimeter and viscometer.Some parameters,including molar ratio of surface active ionic liquid to tetrahydrofuran,volume of SUPRAS,vortex time,p H of sample solution,type and amount of salt,were investigated and optimized.The good linearities(r>0.9990)for the analytes were obtained.The limits of detection and quantification for triazine herbicides were in the range of 1.68-2.14?g kg^-1and 5.61-7.12?g kg^-1,respectively.The spiked recoveries were80.04-119.93%.The SUPRAS prepared in this study has the advantages of simple preparation,low viscosity and good dispersibility.It can be used for the extraction and enrichment of trace triazine herbicides in tea samples.Then,the ionic liquid-based dispersive liquid-liquid microextraction followed by dispersive solid phase extraction(IL-DLLME-DSPE)was developed and applied to the extraction of six sulfonylurea herbicides in soymilk samples.High performance liquid chromatography coupled with diode-array detector(HPLC-DAD)was used for the separation and determination of analytes.In this study,hydrophobic ionic liquid[P_{4 4 4 12}][BF₄]was used as extraction solvent in DLLME and montmorillonite K10 was used as adsorbent in DSPE.After DLLME and DSPE,the ionic liquid and target analytes were adsorbed by montmorillonite K10 and separated from the sample solution.Subsequently,the target analytes were desorbed from montmorillonite K10 by acetonitrile.Some parameters,including type and amount of ionic liquid,p H of sample solution,centrifugal speed and amount of montmorillonite K10,were investigated and optimized.The limits of detection and quantification for sulfonylurea herbicides were in the range of 1.53-2.32?g L^-1and 5.10-7.73?g L^-1,respectively.The relative standard deviations for intra-day and inter-day precision were in the range of 1.12-3.59%and 1.99-6.48%,respectively.When the present method was applied to the analysis of real soymilk samples,the recoveries of the analytes ranged from 81.95%to 118.95%.The results showed that the present method is effective for the extraction of the sulfonylurea herbicides in soymilk samples.