In this three-year proposal, we will focus on (i) preparation of deep eutectic solvents (DESs) as green extracting solvents for microextraction; (ii) application of DESs for the extracting solvents of various emerging contaminants in aquatic and urine samples; (iii) application of DESs to extract various emerging contaminants in indoor dust, biota and vegetable/fruits samples. Deep eutectic solvents, a group of novel “green” solvents, formed by mixing of various quaternary ammonium salts (i.e., choline chloride) and different hydrogen-bond donors (HBD, such as urea, amines or alcohols). They are easily synthesized at room temperature, and no need purification afterward. Therefore, DESs have become attractive alternative solvents for various scientific research, and substituted conventional volatile organic solvents, especially for hazardous chlorinated solvents. In this proposal, we will focus on preparing various properties DESs (i.e., hydrophilicity or lipophilicity) to extract different emerging contaminants from various environmental matrices, biota and food samples. To minimize the number of experiments, costs, and reagents required, optimization of the parameters affecting microextraction sample pretreatment procedures will be done via multivariate experimental designs. The state-of-the-art UHPLC-HRMS will be developed and evaluated for the identification and quantitation of the target analytes at trace-level. Followings four major Tasks are going to be investigated and studied: Task 1. Deep eutectic solvents preparation, characterization and selection to extract various emerging contaminants (i.e., Microcystins, parabens preservatives, high production volume chemicals (HPVs): Benzotriazoles and Benzothiazoles, as the model compounds) in various sample matrices;Task 2. For liquid samples, evaluating DES-based vortex-assisted liquid-liquid microextraction (VA-LLME), ultrasound-assisted liquid-liquid microextraction (UA-LLME). For solid samples, such as indoor dust, biota samples, and vegetables/fruits samples, evaluating modified matrix solid-phase dispersion (MSPD) and modified QuEChERS procedures; Task 3. Optimizing the main parameters affecting microextraction procedures by various multivariate experimental designs (i.e., response surface design coupled with Box-Behnken Design, Plackett-Burman design or central composite design);Task 4. Evaluating the influence of DES in final extract, and for the first time, to evaluate the feasibility of the UHPLC-ESI-HRMS for the identification and quantitation of the target analytes at trace-level.The tasks studied in this proposal will significantly contribute to wide spectrum of DES-based applications in sample pretreatment and microextraction techniques, and also developed the state-of-the-art hyphenated mass spectrometric to determine various emerging contaminants in various environmental and biota samples at trace-level. Eventually, we hope many advantages of DES-based microextraction procedures could fulfill the “green analytical chemistry” guidelines, and could greatly aid future routine analysis and monitoring programs on the occurrence of selected emerging contaminants. Moreover, the results of this research should be highly in response to our environmental protection trends, promote food safety and public health concern, as well as conservation and pollution control policies in Taiwan.