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1 Screening Mercury Levels in Fish with a Selective Fluorescent Chemosensor Christopher J. Chang* J. Am. Chem. Soc. 2005, 127, 16030-16031.

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Presentation on theme: "1 Screening Mercury Levels in Fish with a Selective Fluorescent Chemosensor Christopher J. Chang* J. Am. Chem. Soc. 2005, 127, 16030-16031."— Presentation transcript:

1 1 Screening Mercury Levels in Fish with a Selective Fluorescent Chemosensor Christopher J. Chang* J. Am. Chem. Soc. 2005, 127, 16030-16031

2 2 Mercury The long atmospheric residence time of Hg 0 vapor and its oxidation to soluble inorganic Hg 2+ provides a pathway for contaminating vast amounts of water and soil. The bacteria living in the sediments of aqueous environments transform inorganic Hg 2+ into methylmercury, a potent neurotoxin that concentrates through the food chain in the tissues of fish and marine mammals.

3 3 Current techniques for mercury screening: Atomic absorption/emission spectroscopy Inductively coupled plasma mass spectrometry Fluorescent platforms for Hg 2+ detection: Small molecules DNAzymes Protein Oligonucleotide

4 4 Synthesis of Mercuryfluor-1 (MF1) 71% 75% 9% 37%

5 5 Fluorescence response of 1 μM MF1 to Hg 2+ in aqueous solution. Spectra shown are for Hg 2+ concentrations of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1.0, 1.2, 1.6, and 2.0 μM. Spectra were acquired in 20 mM HEPES (pH 7) with excitation at 480 nm.

6 6 Fluorescence responses of MF1 to various metal ions. Bars represent the final integrated fluorescence response (F f ) over the initial integrated emission (F i ). Initial spectra were acquired in 20 mM HEPES, pH 7. White bars represent the addition of an excess of the appropriate metal ion (1 mM for Li +, Na +, K +, Mg 2+, and Ca 2+, 67 μM for all other cations) to a 1 μM solution of MF1. Gray bars represent the addition of 6.7 μM Hg 2+ to the solution. Excitation was provided at 495 nm, and the emission was integrated over 505-700 nm. 1. Hg 2+ ; 2. Li + ; 3. Na + ; 4. K + ; 5. Mg 2+ ; 6. Ca 2+ ; 7. Sr 2+ ; 8. Mn 2+ ; 9. Fe 2+ ; 10. Co 2+ ; 11. Ni 2+ ; 12. Cu 2+ ; 13. Zn 2+ ; 14. Cd 2+ ; 15. Pb 2+.

7 7 Ionic radii Metal ionLi + Na + K+K+ Mg 2+ Ca 2+ Sr 2+ Mn 2+ Fe 2+ Ionic radius (pm) 90116152861141329792 Metal ionCo 2+ Ni 2+ Cu 2+ Zn 2+ Cd 2+ Pb 2+ Hg 2+ Ag + Ionic radius (pm) 88.5838788109133116129

8 8 Fluorometric analysis of mercury in fish using MF1. Fish were taken from California waters and digested with microwave irradiation, and emission responses were calibrated versus independent measurement of mercury content by atomic absorption spectroscopy: Lime Saddle Marina (bluegill, 0.1 ppm Hg), Calero Resevoir (bass, 1.0 ppm Hg), Lake Almaden (bass, 2.5 ppm Hg), Almaden Resevoir (bass, 5.5 ppm Hg), Guadelupe Resevoir (bass, 7.5 ppm Hg). Excitation was provided at 495 nm, and the emission was integrated over 505-700 nm.

9 9 Figure. Fluorescence metal titrations. The Hg(II) reaction is 87% complete and the Ag(I) reaction 73% complete after 10 min under stoichiometric conditions and at room temperature. J. Am. Chem. Soc. 1992, 114,9704-9705 ref6

10 10 Figure. Relative fluorescence intensities of 1 (2.74 10-5 M) and 2 (2.75 x10 -5 M) in the presence of various metal cations (c = 2.8 x10 -3 M, only for Cd 2+ c = 4.5 x10 -3 M), complete complexation. 1 2 J. Am. Chem. Soc. 1999, 121, 5073-5074 ref7

11 11 J. Am. Chem. Soc. 2000, 122, 968-969 ref8

12 12 fluorescence resonance energy transfer (FRET) Angew. Chem. Int. Ed. 2004, 43, 4300–4302 ref21

13 13 以適當的霧化器 (Nebulizer) 將待測樣品溶液先經霧 化處理後,再配合載送氣流輸送,將所形成含待分 析元素之氣膠 (Aerosol) 輸送至電漿 (Plasma) 中,樣 品受熱後,經由一系列去溶劑、分解、原子化 / 離子 化等反應,將位於電漿中之待分析元素形成單價正 離子,再透過真空界面傳輸進入質譜儀 (Mass spectrometer) ,繼而配合質量分析器 (Mass- analyzer) 將各特定質荷比 (Mass-to-charge ratios) 之離子予以解析後,再以電子倍增器加以檢測,來 進行多元素之定性及定量工作。


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