微波電漿原子發射光譜儀於食用油之分析應用

The Analytical Application of Microwave Plasma Atomic Emission Spectrometer for edible oils

洪丞賢(Hung, Cheng Hsien)

指導教授 ： 凌永健

國立清華大學/理學院/化學系/碩士(2016年)

摘要

微波電漿原子發射光譜法（MP-AES），為以微波磁場誘導所產生的氮氣電漿作為光源之元素分析技術，相較於其他元素分析法，此種技術於分析上的花費較少，亦能同時進行多元素的分析。然而，食用油中的有害金屬含量低，需要靈敏度高的儀器進行分析，加上來自樣品的基質干擾，使此種技術於食用油品之分析備受挑戰，因此研究中將針對食用油之前處理技術進行改善，以利後端儀器之分析。本研究將對於微波酸消化法與液液萃取法這兩種前處理技術進行探討。
於微波酸消化法的部分，研究中為將油樣品以4種不同之試劑條件進行消化。由UV-Vis與MP-AES的分析結果顯示，0.3 mL 的油樣品+ 8 mL之濃硝酸為最佳化條件，而經分析109469 Multi-element Standard II （CAS No. 8012-95-1）得到的回收率為80~111%，驗證此條件之可靠度。
研究第二部分，使用5%之硝酸作為萃取試劑，並結合超音波震盪的技術，以萃取食用油中的重金屬。於研究中，對於超音波震盪溫度、時間與離心時間等參數進行探討，而優化之方法適用之油種為：橄欖油、葵花油、葡萄籽油、大豆油、玄米油、芥花油與芝麻油等7種。再以主成分分析的統計方法與ICP-MS分析結果比對，得到之結果相當，故驗證建立之方法可應用於單一油種之鑑偽。

關鍵字

主成分分析 ； 食用油 ； 液液萃取 ； 微波電漿原子發射光譜儀 ； 重金屬 ； 超音波輔助 ； 微波酸消化

並列摘要

Microwave plasma atomic emission spectroscopy (MP-AES), which uses nitrogen as plasma gas is an interesting development in analytical science sine the running cost can be remarkably reduced in comparison to the inductively coupled argon plasma. However, the determination of trace elements in edible oils needs very sensitive instrumental techniques such as ICP-OES or ICP-MS because of the low concentrations of trace elements in the samples. Furthermore, the high organic content of oil matrix increases the possibility of interference during analysis. In order to figure out these problems, we focused on improving the pretreatment of edible oils in this study. The research was divided into two parts: microwave acid digestion (MAD) and liquid-liquid extraction (LLE).
For MAD, edible oil was digested by different reagent conditions. The optimized condition：0.3 mL oil sample + 8 mL con. HNO3 was based on the results of UV-Vis and MP-AES. We also verified the assurance of this method by analyzing certified reference material (recovery: 80~111%).
In the second section, ultrasound-assisted liquid–liquid extraction was used to pretreatment oil samples. The experimental parameters: sonication temperature, sonication time and centrifugation time were optimized to improve the sensitivity and detect the metals in minimum time. The proposed procedure of combining MP-AES can be regarded as a new procedure for the determination of metals in various edible oils (olive oil, sunflower oil, grape seed oil, soybean oil, rice bran oil, canola oil and sesame oil). For the purpose of detecting tendencies in the samples of the same type of oil, principal components analysis was used and the results for LLE MP-AES were compared with MAD ICP-MS.

並列關鍵字

principal components analysis ； edible oil ； liquid-liquid extraction ； Microwave plasma atomic emission spectroscopy ； metal ； Ultrasound-Assisted Extraction ； microwave acid digestion

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