| Summary: | 碩士 === 國立清華大學 === 化學系 === 97 === People who live in a healthy environment can have healthy body. Therefore, it is important to protect the environment and continuing monitoring the toxic substances, such as insecticide, herbicide and so on, in environment and evaluate the effects on human and ecology. However, the analytes in environmental samples are often present at only trace concentrations and the matrix are complicated. Sample preparation is therefore the most time-consuming and challenging step in environmental analysis. And large amount of organic solvent is required. For meet the requirement of green chemistry and high enrichment factor, reduction of solvent consumption and simplification of sample preparation procedure are the research topic for many analytical chemistry laboratories. In this thesis, we are also focus on how to analyze organochlorine pesticide and phenoxyacetic acid herbicide in aqueous sample with a simple pretreatment procedure and low solvent consumption.
In this study, a novel extraction technique “Dispersive liquid-liquid-liquid microextraction” (DLLME-LSC) was been developed. DLLME-LSC was combined with GC/MS system to analyze organochlorine pesticide in aqueous sample. DLLME-LSC is a convenient and simple sample preparation method. Compared to conventional DLLME (Dispersive solvent: 0.5 mL ~ 1.0 mL), reduction of the amount of dispersive solvent are more environmental friendly and lower the solubility of analytes in sample solution. Better extraction efficiency could be obtained. In this experiment, tetrachloroethylene (TCE) was used as extraction solvent and tert-butyl methyl ether (TBME) was used as dispersive solvent. 13 µL of mixture of TCE and TBME was added into sample solution and fine droplets were formed by shaking. The interfacial area between sample solution and extraction solvent was large and good extraction efficiency was obtained in short period (90 sec). The extraction solvent was settled down by centrifugation. 1 µL of extractant was withdrawn and was injected into GC/MS system.
Another novel sample preparation method “Dispersive liquid-liquid-liquid microextraction” (DLLLME) was developed in this study. DLLLME was combined with Ultra performance liquid chromatography (UPLC) to determine phenoxyacetic acid herbicide in aqueous sample. DLLLME was a rapid and environmental friendly sample pretreatment method. Compared to conventional LLLME (Extraction time- 40~60 min), ~2 min was spent for extraction in DLLLME. In this study, 25 µL of 1,1,2,2-tetrachloroethane was used to extract the targeted analytes from donor phase in short period (90 s). And then, the analytes were back-extracted into acceptor phase by mixing organic phase and acceptor phase. Fine droplets were formed by shaking and pumping with syringe in DLLLME. The large interfacial area made good extraction efficiency and shorten the extraction time. Organic phase was separated from donor phase or acceptor phase by centrifugation. And acceptor phase was injected into UPLC system to analysis.
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