開發披覆式晶片型光觸媒輔助還原裝置串連高效能液相層析與感應耦合電漿質譜儀進行環境水樣中無機硒物種之分析研究

Development of Online HPLC-Chip-Based Immobilized Nano-TiO2 Photocatalytic Reduction Device-ICP-MS System for the Determination of Inorganic Selenium Species in Nature Water

林政興(Cheng-Hsing Lin)

指導教授 ： 孫毓璋

國立清華大學/原子科學院/生醫工程與環境科學系/碩士(2010年)

摘要

自從微量元素的毒物學行為與生物化學的作用與其本身的化學形式有非常大的相關性被廣泛證實以來，時至今日，硒物種的濃度分布情形在風險評估及生物化學行為的研究上已成為不可或缺的資訊。在文獻中，利用化學氫化物生成法來串接高效能液相層析及不同類型的線上偵測系統，已經被證實是一非常有效的微量物種分析的方法。然而，因為六價硒 (Se(VI)) 的高還原電位，使得藉由傳統化學方法難以將六價硒轉換成氣態的氫化物。因此，一個可以提供快速且有效的氫化物產生方法的蒸氣生成技術，至今在建立硒物種連線分析系統時仍然是相當關鍵的一環。
近來，本實驗室已發表一套利用HPLC-UV/nano-TiO2-ICP-MS連線系統進行無機硒物種的分析。為增進之前發表分析系統的分析效能，本研究進一步利用聚甲基丙烯酸甲酯 (poly(methyl methacrylate), PMMA) 基材製作晶片光反應器，藉由PMMA高透光效率及介觀流道晶片微小化的特性，來達到增加光觸媒還原的效率以及降低樣品與藥劑的消耗量的目的。除此之外，為求降低作為光觸媒角色的奈米二氧化鈦(nano-TiO2)的消耗量，我們使用高分子電解質 (poly(diallyldimethylammonium chloride), PDADMAC) 輔助二氧化鈦奈米微粒披覆於晶片光反應器的微流道壁上。在完成PMMA晶片製作後，本研究即將晶片光反應器做為串連HPLC與ICP-MS連線系統的界面元件，建立一套可進行環境水樣中的無機硒物種分析的披覆式晶片型光觸媒輔助還原裝置串連高效能液相層析與感應耦合電漿質譜儀之連線分析系統 (Online HPLC-Chip-Based Immobilized Nano-TiO2 Photocatalytic Reduction Device-ICP-MS System) 連線系統。根據本研究實驗結果顯示，利用本研究所開發的光反應器當作HPLC及ICP-MS的介面時，只需要僅僅15秒就可以有效將無機硒物種轉換成氣態的氫化物，所獲得之四價硒 (Se(IV)) 與六價硒 (Se(VI)) 的偵測極限更可低達0.043與0.042 μg L-1。在完成所建立連線分析系統的分析效能測試後，本研究亦實際進行NIST 1643e標準參考水樣及農田灌溉水中Se(IV) 與Se(VI) 的物種分析，根據SRM 1643e標準參考樣品的分析可知，所得的回收率可達97%，此外，連續三次的分析所測得數據的跳動亦均可維持在8% (RSD) 以內；另外，根據真實農田灌溉水的分析結果可知，新竹地區農田灌溉水中Se(IV) 與Se(VI) 的濃度值分別為0.109±0.019 與 0.090±0.013 μg L-1，且其添加回收率皆在96 - 106%之間。顯示本研究所建立之硒物種連線分析系統，除具有提升分析效能、操作簡單、低成本、低藥劑需求以及高樣品傳輸效率等優點外，亦可實際用來進行自然水樣中微量硒物種的分析。

關鍵字

光觸媒 ； 硒物種分析 ； 奈米二氧化鈦 ； 晶片 ； 高效能液相層析 ； 感應耦合電漿質譜儀

並列摘要

Since it has been widely recognized that the toxicological behaviors and the biochemical functions of trace elements are highly dependent on chemical forms, to date, the information on selenium speciation has been considered indispensable for the risk assessment and better understanding of its biological behavior. Nowadays, the coupling of HPLC with different on-line detection systems by chemical hydride generation device has been proven very useful for the speciation of trace elements. However, in view of converting Se(VI) into gaseous hydride by traditional methods is limited by its high oxidation potential, a new on-line vapor generation technique permitting rapid and effective formation of hydride species from Se(VI) is still necessary for the construction of an adequate hyphenated system for the speciation of selenium species.
Recently, an on-line HPLC-UV/nano-TiO2-ICP-MS system for the determination of inorganic selenium species was reported. Toward the goals of improvement of photocatalytical efficiency and reduction in sample consumption, we intended to develop a poly(methyl methacrylate) (PMMA) chip-based photo-reactor as an interfacing device resulting from the specific properties of microspace, and to combine HPLC and ICP-MS for the determination of Se(IV) and Se(VI) in aqueous samples. Meanwhile, to attain low per-unit manufacturing cost and rapid prototyping, a simple CO2 laser engraving technique was employed to fabricate the photo-reactor. Furthermore, to reduce the consumption of nano-TiO2 photocatalyst, we utilized a polyelectrolyte－poly(diallyldimethylammonium chloride) (PDADMAC) to assist the immobilization of nano-TiO2 particles onto the channel surface. Based on our experimental results, the device presented a greater stability in vaporization efficiency and lower baseline noise. Under the optimized condition, it merely needed 15s to transform inorganic selenium into gaseous selenide. The limit of detection of Se(IV) and Se(VI) were 0.043 and 0.042 μg L-1, respectively. For the analysis of irrigation water, the concentration of Se(IV) and Se(VI) were 0.109±0.019 and 0.090±0.013 μg L-1. Through a series of validation by analyzing 1643e Standard Reference Material and natural waters, it indicated that the proposed methods can be applied satisfactorily to the determination of inorganic selenium species in water samples. Based on the achieved analytical results, it also indicated that our developed on-line system is a fast, simple, low cost, low reagent consumption and high sample transportation efficiency method.

並列關鍵字

photocatalyst ； selenium speciation ； Nano-TiO2 ； chip ； HPLC ； ICP-MS

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