| Milk is a nutritious drink in our daily life,which can supplement calcium,protein and other nutrients.However,when high performance liquid chromatography was used to detect herbicides and antibiotics in milk samples,scientific and effective sample pretreatment method plays a vital role prior to chromatographic analysis.At present,liquid-liquid extraction,solid-phase extraction,matrix solid-phase dispersion extraction,cloud point extraction and aqueous two-phase extraction have been used to separate and enrich the target substances in milk.However,these methods are laborious,time-consuming,and require a large amount of organic solvents.The development of simple,green and miniaturized sample pretreatment method will become the trend of future analysis and detection.Deep eutectic solvent（DES）is a liquid substance at room temperature,which is composed of hydrogen bond acceptor（HBA）and hydrogen bond donor（HBD）through intermolecular hydrogen bond.It has the advantages of low volatility,simple preparation process,low cost and high atom utilization rate（up to 100%）.Therefore,a novel DES-based liquid-liquid microextraction coupled with high performance liquid chromatography was established to extract and detect many herbicides and antibiotics in milk samples.The main contents of this paper are as follows:The structural characteristics,physical and chemical properties and detection methods of triazine herbicides,phenylurea herbicides and sulfanilamide antibiotics were mainly introduced.The types,properties,characteristics and application of deep eutectic solvents were elaborated.A vortex-assisted hydrophobic DES dispersion liquid-liquid microextraction method was established to extract and enrich six sulfanilamide antibiotics,such as sulfabenzoyl,sulfamethoxypyridazine,sulfamethoxazole,sulfaisoxazole and sulfanilamide in milk.And the target analytes were separated and determined by high performance liquid chromatography.In this study,tetrabutylammonium chloride was used as HBA,hexafluoroisopropanol was used as HBD,and a novel hydrophobic high-density DES was synthesized as the extraction solvent of dispersive liquid-liquid microextraction.It was dispersed in the deproteinized sample aqueous solution with the help of vortex to increase the contact area between the extractant and the target analyte.After centrifugation,hydrophobic DES was separated from the sample solution.The deep eutectic solvents phase was diluted with acetonitrile and then filtered.The experimental results show that the good linear relationships（r≥0.9991）were obtained,and the LOD and LOQ were 0.67-1.45μg L-1and 2.23-4.83μg L-1,respectively.The intra-day precision and inter-day precision of each target analyte were 0.64-2.23%and 0.79-5.58%,respectively.The spiked recoveries were between 80.90%and 118.60%,and the relative standard deviations were lower than 6.54%.In the present method,hydrophobic DES is used as extractant instead of traditional organic solvent,and vortex and dispersive liquid-liquid microextraction are combined.The sample extraction,separation and purification are integrated into one step.It has the advantages of high extraction efficiency,simple operation and environmental protection,and can be used for the separation and detection of sulfanilamide antibiotics in milk.Vortex-assisted dispersive liquid–liquid microextraction based on the solidifification of sedimentary deep eutectic solvents was developed and applied to the extraction of triazine and phenylurea herbicides in milk samples.In this study,a series of novel hydrophobic deep eutectic solvents were prepared using tetrabutylammonium chloride as the hydrogen bond acceptor and perflfluorooctanol as the hydrogen bond donor,and their structures,viscosities,densities and melting points were determined.The deep eutectic solvent was used as the extraction solvent and dispersed in the sample solution with the assistance of vortex.After extraction,through centrifugation and subsequent cooling in an ice bath,the deep eutectic solvent was solidifified and deposited on the bottom of the centrifuge tube.Subsequently,the deep eutectic solvent combined with the target analytes was diluted and used for chromatographic analysis.Some parameters,including the extraction temperature,type and volume of the deep eutectic solvent,amount of Na Cl,vortex time and p H of the sample solution,were optimized by the single-factor experiment,Plackett-Burman design and Box-Behnken design.The limits of detection and quantifification were in the range of 0.41-0.59μg L-1and 1.37-1.95μg L-1,respectively.The intra-day precision and inter-day precision were in the range of 0.28-2.14%and 2.02-7.99%,respectively.The present method was successfully applied to the determination of triazine and phenylurea herbicides in milk samples. |
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