以液相微萃取法搭配多元素石墨爐原子吸收光譜儀偵測水樣中的鉛、鎘元素

Determination of lead and cadmium in water samples by liquid-phase microextraction coupled with graphite furnace atomic absorption spectrometry.

姜義峰(Yi-Feng Jiang)

指導教授 ： 黃賢達

國立清華大學/理學院/化學系/碩士(2007年)

https://doi.org/10.6843/NTHU.2007.00428

摘要

本研究以三液相動態微萃取法(dynamic liquid-liquid-liquid microextraction, LLLME)結合多元素石墨爐原子吸收光譜儀偵測水樣中的鉛、鎘元素。利用有機相中的螯合劑(dithizone)，螯合水樣裡的重金屬，反萃重金屬至受層(acceptor phase)硝酸中，再與鈀修飾劑一同注入石墨爐內進行偵測。與傳統液液萃取或固相萃取法相比，此法較簡便，溶劑用量大幅減少；相較於固相微萃取法，則具有耗材花費較少的優點。石墨爐原子吸收光譜儀的最佳化溫控程式與鈀修飾劑用量分別為：灰化溫度600℃、原子化溫度2000℃；5μg鈀。探討各種可能影響萃取效率的變因包括：有機溶劑的選擇、予層(donor phase)水樣pH值、受層(acceptor phase)硝酸濃度、螯合劑用量、樣品攪拌速率與萃取時間。在最佳化條件下（1% dithizone/4-nitro-m-xylene萃取液、予層水樣pH=5、受層硝酸濃度10% 、攪拌速率700r.p.m.、萃取時間40分鐘），鉛、鎘的偵測極限分別為0.032 ng/mL、0.037 ng/mL；精密度是以添加低濃度分析物在真實樣品（0.1 ng/mL Pb、0.2 ng/mL Cd），重複分析5次所得相對標準偏差（RSD）表示之。求得Pb、Cd精密度分別為7%、4%。未來工作為添加低濃度待測物於真實樣品，計算相對回收率，若其值落在100±15% 的範圍內，即可用檢量線進行定量。

關鍵字

鉛 ； 鎘 ； 液相微萃取法 ； 石墨爐原子吸收光譜儀 ； 鈀修飾劑

並列摘要

In this thesis, we combined dynamic liquid-liquid-liquid microextraction (LLLME) with multi-elements graphite furnance atomic absorption spectrometry (GFAAS) to determine trace lead and cadmium in water samples. In the extraction step, two elements in 30 mL of the water sample which adjusted to pH 5 (donor phase) were extracted into an organic film containing a chelating agent (1 % dithizone) in 4-nitro-m-xylene and then back-extracted to 5 μL, 10 % nitric acid solution (acceptor phase). 4.5 μL acceptor phase and 0.5 μg palladium (chemical modifier) were injected into the graphite tube by syringe simultaneously. The continual movement of organic and acceptor phases not only resulted in a renewable organic film but also enhanced the enrichment factor. Under the optimized conditions (ashing temp. 600℃, atomization temp. 2000℃, stirring rate 700 r.p.m., extraction time 40 minutes), the detection limits and relative standard deviations (RSDs) were 0.032 ng/mL, 0.037 ng/mL ; 7%, 4% for lead and cadmium, respectively.

並列關鍵字

lead ； cadmium ； liquid-phase microextraction ； GFAAS ； palladium chemical modifier

參考文獻

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Enviroment Principles and Reaction”, John Wiley & Son

Inc., New York, 1986.

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