| Capillary electrophoresis (CE) with its high separation efficiency, low solvent consumption,short analysis time, lower cost advantages, has become an effective separation and analysistechnique. The commonly used CE-UV method has the shortcomings of low detection limit andlow sensitivity, because of its small injection volumes and the short detection optical path length.To solve this problem, an effective sample enrichment method is needed to improve thedetection sensitivity. Dispersive liquid-liquid microextraction (DLLME) with the merit of simple,fast, low cost and high preconcentration factor, is a new type of liquid phase microextractionmethod. It has been widely applied to the extraction enrichment of organic and inorganiccompounds. Choosing the appropriate extraction agent and dispersant determines whetherDLLME can successfully extract the analyte. Green solvent ionic liquid (IL), due to its highdensity, low volatility, good solubility and adjustable physical and chemical properties, has greatadvantage to act as extraction agent of DLLME. Amphiphilic molecule surfactant both candissolve in the organic phase and water phase, can be applied to DLLME as dispersant replacingthe traditional volatile organic solvents. It has the advantages of low solvent consumption andlittle damage to the environment. This thesis mainly applied ionic liquid and surfactant inDLLME coupled with CE to analyse glucocorticoid and anthraquinone compounds in drugs.The specific research content is divided into the following two parts:1. Surfactant-assisted ionic liquid-based dispersive liquid-liquid microextraction(SA-IL-DLLME) coupled with micellar electrokinetic chromatography (MEKC) was developedto determine four glucocorticoids (cortisone, prednisolone, dexamethasone, and triamcinoloneacetonide). Rapid separation of the four glucocorticoids was obtained within8min with the optimum conditions of20mmol/L ammonium acetate,20mmol/Lsodium cholate,15mmol/LSDS at pH9.8. In the IL-SA-DLLME process, a room temperature ionic liquid,1-octyl-3-methylimidazolium hexafluorophosphate ([C8MIM][PF6]), was used as the extractionsolvent and Tween20was used as the dispersant without using any organic solvent that isnormally required in the previously described common dispersive liquid-liquid microextractionmethod. Parameters affecting the extraction efficiency, were investigated and optimized. Underthe optimized conditions, the procedure afforded satisfactory enhancement factors (18.2–31.1)and low limits of detection (0.01–0.1μg/mL) were obtained. The applicability of the techniquewas evaluated by the determination of GCs in typical pharmaceuticals, with good recoveries(82.5%–111.6%).2. A simple and rapid method termed as double dispersant-assisted ionic liquid-baseddispersive liquid-liquid microextraction (DA-IL-DLLME) for simultaneous determination ofthree anthraquinone derivatives including emodin, chrysophanol, and rhein was established bycapillary zone electrophoresis (CZE). An ionic liquid (1-octyl-3-methylimidazoliumhexafluorophosphate) was used as extraction solvent in combination with a mixture of methanoland Triton X-114as dual dispersant for the extraction of anthraquinones. Compared with onlyusing surfactant as emulsifier or dispersant, the addition of methanol permits the extraction of thetargets in a few seconds during manual shaking and avoids using ultrasound-assistedemulsification. The influence factors of experimental conditions for extraction, includingextraction parameters and instrumental conditions, were investigated in detail. Under theoptimized conditions, the detection limits and the enhancement factors are in the range of0.007–0.01μg/mL and46.6–59.8, respectively. The applicability of the technique was evaluatedby the determination of rhubarb in traditional Chinese medicine and clinical drugs, with goodrecoveries (87.5%–105.6%). |
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