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Microemulsion electrokinetic chromatography (MEEKC) is a mode of capillary electrophoresis with a wide range of applications in which microemulsion is utilized as background electrolyte to achieve the separation of analytes. Microemulsions are composed of oil droplets, aqueous buffer, surfactant, and co-surfactant. Currently, conventional organic reagents act as the most commonly used oil phase in microemulsions, which are unfriendly to the environment. Recently, deep eutectic solvent (DES) has become a new type of eco-friendly solvent due to its non-toxicity. Therefore, it is of great value to establish a new MEEKC method by replacing conventional organic reagents as the oil phase with DES. The novel DES/W MEEKC method was established for phenolic compounds in Senecio scandens samples. Single-factor experiments and response surface methodology were performed to systematically optimize the crucial parameters for the method, including the type and content of the oil phase, surfactant content, concentration of borax buffer, and pH of the background solution. Under the optimized conditions, satisfactory regression curves were established for all standard analytes with correlation coefficients ≥0.9990. The method featured high sensitivity and favorable accuracy, with the instrumental detection limit in the range of 0.22–1.04 μg/mL, and intraday and interday precision for migration time expressed as relative standard deviations of 0.18–0.82% and 1.25–2.50%, respectively. The DES/W MEEKC method was successfully applied to Senecio scandens with good recoveries of 87.72–106.99%. In conclusion, the newly established DES/W MEEKC method is highly efficient, green and environmentally friendly. DES is considered a green and efficient solvent. The DES/W MEEKC method is highly efficient and environmentally friendly. Actually, the method provides a novel and effective analytical tool for the simultaneous separation and determination of multiple phenolic compounds, especially in complex plant matrices. In the future, the DES/W MEEKC method still has the prospect of being widely used in the separation of other complex phytochemicals. [Display omitted] • Deep eutectic solvent-in-water MEEKC was established. • Deep eutectic solvent was employed as the oil phase in microemulsion system. • Single-factor experiments and response surface methodology were performed. • The method was used for the determination of phenolic compounds in complex matrices. • The method was proven to be environmentally friendly and efficient. [ABSTRACT FROM AUTHOR]

[Display omitted] • The one-step admicelle to cyclodextrin sweeping method was established. • The approach was applied in the preconcentration of five toxic aristolochic acids. • The method showed low detection limit with 3–6 ng/mL. • The sensitivity enrichment factors of five aristolochic acids was enhanced to 30–68. One-step admicelle to cyclodextrin sweeping (ACDS) method in capillary electrophoresis (CE) has been developed for the separation and preconcentration of toxic aristolochic acids (AAs) by applying cetyltrimethylammonium chloride (CTAC) between the critical micelle concentration and critical surface aggregation concentration. The analytes were captured into the CTAC admicelles, after the more stable inclusion complexes were formed, the release and preconcentration of the analytes could be realized. The CE enrichment parameters, such as the types of cationic surfactants and cyclodextrins (CDs), the concentration of cationic surfactants, disodium tetraborate decahydrate (borax) and CDs, the volume ratio of acetonitrile (ACN) in background electrolyte (BGE) and the sample injection time were optimized systemically. The optimal BGE was composed of 20 mM borax, 10 mM γ-CD and 10 % (v/v) ACN, the sample matrix consisted of 0.2 mM CTAC, 20 mM borax and five analytes. The limit of detection of this method was 3–6 ng/mL, and good linearity values (R2) were obtained for five AAs in the range of 0.997–0.999. Applying optimized conditions, the enrichment efficiencies of five AAs were enhanced with the sensitivity enrichment factors of 30–68. The sweeping approach was successfully applied to the determination of A, B, Ⅶ a , C and D in Aristolochia and Asarum samples, which could provide a potential in the enrichment of the other toxic compounds. [ABSTRACT FROM AUTHOR]