Study On The Extraction Of Naphthoquinone Pigments And Pyrethroid Insecticides By The New Aqueous Two-Phase System

In recent years,a variety of sample pretreatment methods were applied to the extraction and separation of active components of Chinese herbal medicines,antibiotics,biomolecules and metal ions.However,the concentration of these components in the matrix is very low and the matrix components are complex.Thus,sample pretreatment method is particularly important step in the whole analysis process.Traditional pretreatment methods are usually effective,but they are time-consuming.A large number of volatile,toxic and harmful organic solvents were required.Therefore,green,simple,rapid and miniaturized sample pretreatment method has aroused great interest.Aqueous two-phase extraction is a mild and eco-friendly liquid-liquid extraction technique,which has been applied to the extraction and separation of bioactive components and food toxic and harmful ingredients.It has the advantages of simple operation,mild property,less denaturation,fast separation speed,fast mass transfer,selective separation and easy amplification.In this paper,aqueous two-phase systems based on ionic liquids and deep eutectic solvents were developed for the extraction of naphthoquinone pigments in Chinese herbal medicines and pyrethroid insecticides in fruits.And high-performance liquid chromatography was used for the separation and determination of target analytes.In chapter 1,the basic characteristics,extraction principle and influencing factors of aqueous two-phase system were introduced.The types and properties of ionic liquids and deep eutectic solvents which were used to the aqueous two-phase extraction were mainly introduced in this chapter.The properties,application and analytical technique of naphthoquinone pigments in Arnebia euchroma?Royle?Johnst.and pyrethroid insecticides were summarized.In chapter 2,a simple,rapid and green ultrasound-assisted ionic liquid/anionic surfactant aqueous two-phase extraction?UA-IL/AS-ATPE?method was developed and applied to the extraction of shikonin,acetylshikonin and?,?'-dimethylacrylshikonin in Arnebia euchroma?Royle?Johnst..The separation and determination of the analytes was performed by high-performance liquid chromatography coupled with diode array detection.In the study,1-butyl-3-methylimidazolium tetrafluoroborate?[C₄MIM][BF₄]?was used as extraction solvent.Ionic liquid-based solid-liquid extraction and aqueous two-phase extraction were performed simultaneously in one tube under the assistance of ultrasound.The liquid-liquid-solid three-phase systems,namely surfactant-rich phase,water-rich phase and sample-rich phase,was formed.The target analytes were enriched in surfactant-rich phase.Under the optimal experimental conditions,the calibration curves of target analytes showed good linear relationship?r?0.9997?.The inter-day and intra-day precision were in the range of 3.42-8.53%and 1.98-3.14%,respectively.The LODs and LOQs for the target analytes were in the range of 5.0-19.2 ng mL^-1and 16.7-64.2 ng mL^-1,respectively.The recoveries of naphthoquinone pigments ranged from 90.00%to 97.73%and relative standard deviations were less than 4.50%.Compared with heat reflux extraction?HRE?and ultrasonic-assisted extraction?UAE?,the proposed method is simpler,faster and more effective,because the mass transfer process for the analytes was always performed in one centrifugal tube and the steps such as filtration,concentration and redissolution were avoided.The present method was demonstrated to be efficient and satisfactory for the extraction of naphthoquinone pigments in medicinal plants.In chapter 3,a novel deep eutectic solvents-based aqueous two-phase extraction coupled with high performance liquid chromatography?DES-ATPE-HPLC?method was developed and applied to the extraction of five pyrethroids in fruits,including flucythrinate,cyfluthrin,fenvalerate,permethrin and bifenthrin.In this study,hexafluoroisopropanol was used as the hydrogen bond donor and choline chloride was used as the hydrogen bond acceptor.A novel deep eutectic solvent was prepared through strong hydrogen-bonding interaction between hydrogen donor and hydrogen acceptor.Subsequently,the aqueous two-phase system composed of deep eutectic solvents and salt was established.The target analytes were enriched in deep eutectic solvents.In this study,the single variable analysis and response surface analysis were used to optimize the parameters such as the type of salt,the amount of salt,the amount of deep eutectic solvents,bath temperature,bath time,centrifugal speed and the pH value of the extraction medium.The experimental results showed that good linear relationship was obtained?r?0.9991?.The LODs and LOQs were 0.68-4.41?g kg^-11 and 1.75-7.81?g kg^-1,respectively.The recoveries of the spiked samples were 101.68-119.39%with the RSDs lower than 7.20%.The inter-day and intra-day precision were in the range of 3.09-8.92%and 2.62-7.20%.This present method combined the advantages of a new eutectic solvent and aqueous two-phase extraction,and can be used for the extraction and analysis of pyrethroid pesticides residues in fruits.