環境水樣中有機氯農藥及苯氧乙酸除草劑之綠色萃取方法之探討

Green extraction method for Analysis of organochlorine pesticides and phenoxyacetic acid herbicides in aqueous samples

蔡宛君(Wan-chun Tsai)

指導教授 ： 黃賢達

國立清華大學/理學院/化學系/碩士(2009年)

https://doi.org/10.6843/NTHU.2009.00286

摘要

環境與人是生命共同體，居住在健康的環境才能有健康的身體，因此人們開始意識的環境保護的重要，也開始針對環境中各種對人體有害的物質如殺蟲劑、除草劑等進行監控。但因環境樣品的基質成份較複雜且待測物的含量較低，進行檢測前，常須繁瑣的樣品前處理的步驟及耗費大量的有機溶媒。為了符合環境保護及檢驗效率，減少有機溶媒的使用量及簡化樣品前處理步驟一直是許多分析化學實驗室努力的目標。而本篇論文的研究目標，也是朝這個方向前進，希望能利用極少量的有機溶媒及簡單的前處理步驟快速地萃取水中的有機氯農藥及苯氧乙酸類的除草劑。
在本研究中，開發出一新的萃取技術“微量溶劑分散液液微萃取”(Dispersive liquid-liquid microextraction with little solvent consumption)，用以萃取水樣有機氯農藥搭配氣相層析質譜儀進行檢測。“微量溶劑分散液液微萃取”是一個快速且簡便的方法，與一般的分散液液微萃取法比較(有機溶劑使用量為0.5 mL ~1.0 mL)，本實驗大量減低分散劑的使用量(本實驗分散劑使用量為7.8 L)，不僅較符合綠色化學的宗旨，也因樣品溶液中所含有的分散劑較少，可溶解在樣品溶液中的分析物量減低，因此萃取液對分析物可以達到較佳的萃取效果。在本實驗中，使用四氯乙烯當做萃取溶媒，分散劑則為甲基第三丁基醚，總共加入樣品溶液的有機相體積為13 µL，藉由手上下震盪離心管的幫助，來使得萃取液形成微小的液滴，提高萃取相與樣品溶液的接觸面積，以達到快速萃取(總共萃取時間90秒)的效果。接下來再藉由離心機使萃取液沉降於離心管底部後，利用注射針取出，注入氣相層析質譜儀進行分析。
本研究並開發出新的“分散式三相微萃取”(Dispersive liquid-liquid-liquid microextraction)技術，並以萃取水樣中苯氧乙酸除草劑並搭配極致效能液相層析儀進行檢測，探討本分析方法的可行性。“分散式三相微萃取”是一個快速且對環境較友善的分析方法，與傳統的三相微萃取法比較(萃取時間約為40分鐘至60分鐘)，本實驗大量減低萃取所需的時間(萃取時間約為2分鐘)，達到快速萃取的效果。在本實驗中，使用25 µL的1,1,2,2-四氯乙烷當做萃取溶媒，先將接受相(donor phase)中的分析物快速地萃取至有機相後，再將有機相與接受相均勻混合使分析物再被反萃取至接受相(acceptor phase)中。實驗操作過程中，藉由手上下震盪離心管與以針筒抽動的方式使有機相在水相中形成微小的液滴，提高萃取相與提供相及接受相的接觸面積，以達到快速萃取的效果，並藉由離心機使有機相與提供相及接受相分離後，再將接受相利用極致效能液相層析儀搭配自動注射器進行分析。

關鍵字

微量溶媒分散液液微萃取 ； 分散式三相微萃取 ； 有機氯農藥 ； 苯氧乙酸除草劑

並列摘要

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.

參考文獻

[1] 行政院衛生署 97年死因統計結果分析

[4] 行政院環境保護署環署水字第0039159號，民國87年06月04日

[5] 行政院環境保護署環署水字第0081750號，民國90年12月26日

[13] 行政院環境保護署環署毒字第0960100652號, 民國97年01月02日.

[14] 行政院環境保護署環署水字第0039159號，民國87年06月04日