| Summary: | 碩士 === 國立清華大學 === 化學系 === 99 === A novel sample preparation method “Dispersive liquid-liquid microextraction” (DLLME) coupled with gas chromatography–electron capture detector (GC-ECD) was developed for the analysis of organochlorine pesticides (OCPs) in aqueous samples. DLLME is a convenient and simple sample preparation method. In the study, the organochlorine pesticides consisted of lidane, heptachlor, α-endosulfan, o,p’-DDD, endrin, dieldrin, p,p’-DDE and aldrin. The procedure doesn’t need any dispersive solvent. Only the less toxic 1-decanol was used as extraction solvent, and using handshaking and ultrasound-assisted emulsification method to extract analytes. Handshaking before ultrasound-assisted emulsification is essential for effective extraction. Ultrasound was applied to accelerate the emulsification of organic solvent in aqueous solutions. It can enhance the extraction efficiency. We also aim to study the effect of horizontal and vertical directions and different sites in Ultrasonic bath. Then, we used improved solvent collection system (ISCS) to reduce the amount of extraction solvent using. After centrifugation, 1 µL of extraction solvent was injected into GC-ECD. Under the optimum conditions, the results indicate that linear range of the method was 5-2500 ngL-1 for the most of the OCPs and the LODs of method ranged from 0.6 to 2.9 ngL-1.The relative recoveries ranged from 75% to 107% for sea water and from 70% to 99% for field water. Good enrichment factor and minimization the consuming of organic solvent were obtained. The method provides a rapid, simple and environmental friendly procedure for determining OCPs in aqueous samples.
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