Development of online HPLC-PMMA Chip-based Photo-Catalyst Reduction Device (PC2RD)-ICP-MS hyphenated system for determination of selenium species in nature water

自然界中硒的基本性質以及毒性除與樣品中硒的濃度有關外，也與硒存在的化學形態有著極為密切的關係。一般而言，自然界的水體中，可溶性的硒主要以亞硒酸鹽及硒酸鹽的形態存在。硒在環境中的宿命(fate)與生物效應(biological effect)皆會隨其存在的物種型態不同而不同，因此，環境水體中不同硒物種分佈的資訊在探討硒的地球化學行為及生物效應的過程中一直扮演著極為重要的角色。然而自然環境中個別硒物種的含量極低且環境水樣的基質又極為複雜，因此需要一選擇性好且極為靈敏的分析方法，才能滿足硒物種分析的需求。氫化物生成系統是目前最常用來提高樣品傳輸效率及分析靈敏度的進樣方式，近年來由本實驗室所開發之光催化反應裝置(PCRD)，已被證實確可大幅增進分析的靈敏度，然而PCRD採用鐵氟龍管做為反應器，鐵氟龍對於UV光穿透效率較差，因此，為進一步提高分析系統的靈敏度，本研究的目的旨在開發第二代的光催化還原反應裝置介面—PMMA Chip-based Photo-Catalytic Reduction Device (PC2RD)，此界面係利用二氧化碳雷射雕刻機(CO2-Laser Engraver)在聚甲基丙烯酸甲酯(PMMA)高分子材料上刻劃出預先設計好的介觀流道(meso-channel)，待製作完成實驗所需的晶片型反應器後，再搭配主波長為365 nm汞燈的使用，即可成功地將欲分析的無機硒物種進樣效率提升達20%左右。另外，經測試發現，本研究所製造之界面元件僅需29 秒，即可將無機硒物種還原成為氣態的硒物種，在最佳化的操作條件下，所得到的偵測極限分別為0.0049 (Se(Ⅳ))及0.0039 (Se(Ⅵ)) □g/L。在完成所建立連線分析系統的分析效能測試後，本研究亦實際進行河川水體中硒物種的分析，結果發現Se(Ⅵ)在所分析河水中的濃度為0.096±0.020 □g/L，不同物種的添加分析回收率均介於95-102%，顯示本研究所建立之HPLC-PC2RD-ICP-MS硒物種連線分析系統，除具有提升分析速度，操作簡單及高樣品傳輸效率等優點外，亦實際可用來進行自然水樣中微量硒物種的分析。

關鍵字

聚甲基丙烯酸甲酯；光催化；二氧化鈦；晶片；蒸氣產生；硒

並列摘要

Recently, speciation of selenium has attracted wide attention not only because the narrow threshold concentration range between deficiency and toxicity, but also its complexity in phisco-chemical form presenting in various environment and biological media. In general, the major soluble forms of selenium in nature waters have been proven to be selenite and selenate. The concentrations of selenium species in nature waters are extremely low; therefore, it is of great important to develop a sensitive and selective method for the study of the fate of selenium species in aqueous environment. According to literatures, undoubtedly, HPLC-ICP-MS hyphenated technique is one of the most sensitive method for the determination of trace selenium species. However, the analytical sensitivity of ICP-MS for selenium is highly limited by the high ionization energy (9.75 eV) of selenium and the inferior transport efficiency (mostly 2–3%) provided by traditional sample introduction systems. To compensate for the inferiority of HPLC-ICP-MS system, hydride generation (HG) technique has been successfully used to interface chromatography and spectrometers by enhancing analyte transportation efficiency and sensitivity. Recently, a novel photo-catalyst reduction device (PCRD) was developed, which has been verified as an efficient and high-performing technique for selenite and selenate detection. Because the PCRD was constructed by a PTFE tube, in this study, we intended to develop a PMMA (polymethylmethacrylate) Chip-base photo-catalyst reduction device (PC2RD) to improve the light transmission and sensitivity of detection. After the fabrication of meso-fluidic chip by CO2-Laser engraver, a UV lamp with 365 nm wavelength was used for the irradiation. Based on the experimental results, PC2RD system could improve the transport efficiency of analyte selenium species by 20%, comparing to PCRD system. Moreover, it merely needed 29s to transform inorganic selenium into gaseous selenide. The limit of detection of Se(Ⅳ) and Se(Ⅵ) were 4.9 and 3.9 ng/L, respectively. Based on the achieved analytical results, it indicated that our developed HPLC-PC2RD-ICP-MS system is a fast, simple and high sample transportation efficiency method, and has the ability to determine different selenium species in natural waters.

並列關鍵字

PMMA ； photo-catalyst ； TiO2 ； Chip-based ； vapour generation ； selenium

參考文獻

[1] Lemly, A.D., Aquatic selenium pollution is a global environmental safety issue, Ecotoxicology and Environmental Safty, 2004, 59, 44-56

[3] Lemly, A.D. Symptoms and implications of selenium toxicity in fish: the Belews Lake case example, aquatic toxicology, 2002, 57,39-49

[4]Dumont, E.; Vanhaecke, F; Cornelis, R., Selenium speciation from food source to metabolites: a critical review, Anal. Bioanal. Chem., 2006, 385, 1304-1323

[5] Ba~nuelos, G.S.; Lin, Z.Q., Acceleration of selenium volatilization in seleniferous agricultural drainage sediments amended with methionine and casein, Environmental Pollution, 2007, 150, 306-312

[6] Chung, J.W.; Erenverg, R.; Rittmann, B., Bioreduction of Selenate Using a Hydrogen-Based Membrane Biofilm Reactor Environ. Sci. Technol., 2006, 40, 1664-1671

國際替代計量

Development of online HPLC-PMMA Chip-based Photo-Catalyst Reduction Device (PC2RD)-ICP-MS hyphenated system for determination of selenium species in nature water

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