奈米二氧化鈦固相萃取分離法配合流動注入原子吸收光譜儀於重金屬物種分析方法開發及其生醫與環境分析應用之研究

Nano-TiO2 Solid-phase Extraction/Separation Coupled with Flow Injection－Atomic Absorption Spectrometer for Heavy Metal Speciation and Its Biomedical and Environmental Applications

李正發(Cheng-Fa Lee)

指導教授 ： 黃友利

高雄醫學大學/醫學院/醫學研究所/博士(2012年)

摘要

本研究旨在發展奈米二氧化鈦 (Nano-TiO2) 固相萃取分離技術配合流動注入原子吸收光譜儀之重金屬物種分析方法，經由各種分析條件之最適化探討並驗證分析方法之可靠性後，實際應用於人體尿液及環境水樣中重金屬物種之檢測與分析。本研究內容主要分成三大部份：第一部份，利用Nano-TiO2固相萃取分離技術配合流動注入電熱式原子吸收光譜儀之連線系統進行尿液中無機硒物種分析方法之開發。利用0.02 M氫氧化鈉溶液作為流湜液，將四價硒與六價硒從Nano-TiO2薄膜脫附，並藉由流動注入系統將流湜液導入石墨管中進行硒物種之分析。研究結果顯示四價硒與六價硒之偵測極限分別為0.31與0.25 μg L-1；四價硒與六價硒之分析精密度介於2.1至7.4%之間；尿液中四價硒與六價硒之添加回收率介於93.9至112.2%之間；於分析糖尿病患者尿液中四價硒與六價硒之平均濃度為5.7與10.5 μg L-1。第二部份，發展Nano-TiO2薄膜/UV光催化系統、流動注入系統與電熱式原子吸收光譜儀之鉻物種分析方法，利用Nano-TiO2光催化裝置進行尿液中三價鉻與六價鉻之物種吸附分離，進而以1.0 M甲酸配合光催化達到六價鉻還原與三價鉻之脫附。研究結果顯示三價鉻與六價鉻之偵測極限分別為0.08和0.13 μg L-1；三價鉻與六價鉻之精密度介於4.0至6.2%；尿液中三價鉻與六價鉻之回收率介於96.0至98.3%；本方法成功地應用於探討口服吡啶甲酸鉻前後尿液中三價鉻與六價鉻之變化。第三部份，基於砷物種分析之複雜性，利用Nano-TiO2薄膜可同時分離四種砷物種之特性，建立Nano-TiO2固相萃取分離技術配合電熱式原子吸收光譜儀之砷物種分析方法。本方法利用Nano-TiO2薄膜於pH 3或pH 10時情況下進行砷物種之吸附，再以50 mM磷酸二氫銨、50 mM草酸二銨與50 mM醋酸銨溶液進行砷物種之脫附分離。研究結果顯示三價砷、五價砷、單甲基砷與雙甲基砷之偵測極限分別為0.17、0.18、0.14與0.11 μg L–1；三價砷、五價砷、單甲基砷與雙甲基砷之精密度介於0.7至8.1%之間；實際水樣中砷物種之添加回收率介於90.4至107.3%之間；本方法應用於環境水樣中三價砷、五價砷、單甲基砷與雙甲基砷之結果顯示，本方法可以成功地分析井水中四種砷物種之濃度。總結本研究之成果顯示Nano-TiO2固相萃取分離技術配合原子吸收光譜法於各類微量重金屬之物種分析方法開發具備新穎與前瞻性，將有助於重金屬物種在生醫與環境相關議題之探究。

關鍵字

奈米二氧化鈦 ； 固相萃取分離法 ； 原子吸收光譜儀 ； 重金屬物種分析

並列摘要

This study describes the development of analytical methods that used nano-TiO2 solid-phase extraction/separation coupled with flow injection (FI)－atomic absorption spectrometry (AAS) for heavy metal speciation. The proposed nano-TiO2 solid-phase extraction/separation－FI－AAS system was validated and applied to the detection of heavy metal species in human urine and environmental water samples. Three methods are presented in this study. Firstly, an on-line nano-TiO2 solid-phase extraction/separation coupled with FI－electrothermal AAS (ETAAS) system was developed for the separation of Se(IV) and Se(VI) in urine samples. The 0.02 M NaOH solution was used to elute the Se(IV) and Se(VI) species from the surface of nano-TiO2 film reactor and the eluent was introduced into the graphite tube by a flow injection system. The detection limits was 0.31 μg L-1 and 0.25 μg L-1 for Se(IV) and Se(VI), respectively. The precisions of the developed method for Se(IV) and Se(VI) were in the rages of 2.1 - 7.4%. The recoveries of Se(IV) and Se(VI) in urine samples were in the rages of 93.9 - 112.2%. The average concentrations of Se(IV) and Se(VI) in urine of patients with diabetes mellitus were found to be 5.7 and 10.5μg L-1, respectively. In subsequent part, an on-line nano-TiO2 photocatalysis reduction device coupled with FI-ETAAS was developed for chromium speciation. The process of chromium speciation in urine was based on the adsorption of Cr(III) and Cr(VI) on this photocatalysis reduction device. The absorbed Cr(VI) was photoreduced to Cr(III), and Cr(III) was eluted using 1.0 M formic acid. The detection limit for Cr(III) and Cr(VI) using this analytical method was 0.08 and 0.13 μg L-1, respectively. The precisions for the analysis of Cr(III) and Cr(VI) were in the range of 4.0 - 6.2%. The spiked recoveries were in the range of 96.0 - 98.3% for the determination of Cr(III) and Cr(VI). This analytical method was applied to the determination of Cr(III) and Cr(VI) in urine samples of human volunteers, during which samples were taken before and after the volunteers’ diets supplemented with chromium picolinate. Lastly, due to the complexity for separating the four arsenic speciesof interest, an analytical method was developed for the determination of them in environmental water samples using a nano-TiO2 solid-phase extraction/separation coupled with atomic absorption spectrometry. The separation of the four arsenic species was based on the selective adsorption of arsenic species onto the surface of TiO2 film at pH 3 or 10 and their subsequent selective desorption through elution with 50 mM NH4H2PO4, 50 mM (NH4)2C2O4 and 50 mM CH3COONH4 solution. The detection limits for As(III), As(V), MMA, and DMA was 0.17, 0.18, 0.14, and 0.11 μg L–1, respectively. The precisions of this analytical method for four arsenic species were in the range of 0.7 - 8.1%. The recoveries for As(III), As(V), MMA, and DMA spiked in water samples were in range of 90.4 - 107.3%. This proposed method was successfully applied for the speciation of four arsenic species in well water samples. In summary, the results of this study confirmed that a nano-TiO2 solid-phase extraction/separation coupled with atomic absorption spectrometry would be a novel and foresighted method for trace metal speciation and could benefit the exploration of trace heavy metals in biomedicial and environmental sciences.

並列關鍵字

Nano-TiO2 ； Solid-phase Extraction/Separation ； Atomic Absorption Spectrometer ； Heavy Metal Speciation

參考文獻

[1] A. Kot; J. Namiesńik, The role of speciation in analytical chemistry. Trends in Anal Chem, 2000, 19, 69-79.

[2] A. R. Kumar; P. Riyazuddin, Chromium speciation in a contaminated groundwater: redox processes and temporal variability. Environ Monit Assess, 2011, 176, 647-662.

[3] B. Michalke, Element speciation definitions, analytical methodology, and some examples. Ecotoxicol Environ Saf, 2003, 56, 122-139.

[4] C. Zheng; L. Wu; Q. Ma; Y. Lv; X. Hou, Temperature and nano-TiO2 controlled photochemical vapor generation for inorganic selenium speciation analysis by AFS or ICP-MS without chromatographic separation. J Anal At Spectrom, 2008, 28, 514-520.

[5] E. V. Alonso; A. Garcia de Torres; J. M. Pavon, Flow injection on-line electrothermal atomic absorption spectrometry. Talanta, 2001, 55, 219-232.