The High Sensitivity Study Of High Performance Capillary Electrophoresis With Liquid Microextraction

Capillary electrophoresis plays a significant impact in the field of analyticalchemistry, due to numerous advantages which are high efficiency, fast, low solventand sample consumption, more separate modes, friendly to enviroment and so on.However, many shortcoming of CE limit its rapidly application, especially in traceanalytes field. These drawbacks, such as small inject amout of sample and shortoptical pathlength, lead to low detection sensitivity. Hence, a lot of preconcentrationmethods appear in order to improve enrichment ratio. Liquid phase microextractioncauses attention of many researchers. This study mainly focus on dispersive liquid-liquid microextraction and fiber hollow liquid phase microextraction, adopts novelextraction type and microemulsion for increase sensitivity of method. New processesexpand application of CE in microscale and trace analytical compotent.First part, for the first time, dispersive liquid-liquid microextraction (DLLME)was developed for the fast, simple, and efficient determination of chlorophenols inwater samples followed by MECC. The extraction of chlorophenols in the aqueoussample solution was performed in the presence of extraction solvent (chloroform)and dispersive solvent (acetone). A demulsification solvent (acetonitrile) was theninjected into the aqueous solution to break up the emulsion, the obtained emulsioncleared into two phases quickly. The lower layer (chloroform) was collected andanalyzed by FESI-RMM in capillary electrophoresis. Several important parametersinfluencing the extraction efficiency of HSD-DLLME such as the type and volume ofextraction solvent, disperser solvent and demulsification solvent, sample pH,extraction time as well as salting-out effects were optimized. Under the optimizedconditions, the proposed method provided a good linearity in the range of0.02-4g/mL, low limits of detection (4ng/mL), and good repeatability of the extractions(RSDs below9.3%, n=5). And enrichment factors for three phenols were684,797and233, respectively. This method was then utilized to analyze two real environmental samples from wastewater and tap water and obtained satisfactoryresults. The obtained results indicated that the developed method is an excellentalternative for the routine analysis in the environmental field.Second part, microemultion enhanced hollow fiber microextraction (ME-HFME)was developed firstly for the fast, simple, and efficient determination of phthalate acidesters in water samples and hunman urine followed by MECC. Methylbenzene-isopropanol-water ternary microemulsion act as extraction solvent which is dispersedinto fiber hollow cell pore. Throw the HF bar into sample aqueous solution withmagnetic stirring. After the extraction process finished, take out HF and add organicsolvent to release analytes. Several important parameters influencing the extractionefficiency of SFME-HFME such as the type of extraction solvent, constitute ofternary microemulsion, extraction time, desorption time as well as salt effect wereoptimized. Under the optimized conditions, the proposed method provided a goodlinearity in the range of0.16-3.2μg/mL,0.4-8μg/mL,1.6-80μg/mL (DMP, DEP, DBP)and good repeatability of the extractions (RSDs below9.0%, n=5).This method wasthen utilized to analyze two real environmental samples from wastewater and tapwater and biological sample from healthy human urine, then all obtained satisfactoryresults. The obtained results indicated that the developed method is an excellentalternative for the routine analysis in the chemical analysis field.