Determination of mercury in fish otoliths by cold vapor generation inductively coupled plasma mass spectrometry (CVG-ICP-MS)

TALANTA

卷:93

Article; Proceedings Paper

Kenduzler, Erdal¹  Ates, Mehmet¹  Arslan, Zikri¹  McHenry, Melanie²  Tchounwou, Paul B.² 

[1] Jackson State Univ, Dept Chem & Biochem, Jackson, MS 39217 USA

[2] Jackson State Univ, Environm Sci PhD Program, Jackson, MS 39217 USA

关键词: Fish otolith;    Inorganic mercury;    Total mercury;    Cold vapor generation;    ICP-MS;   

DOI  :  10.1016/j.talanta.2012.02.063

来源: Elsevier

【 摘 要 】

A method based on cold vapor generation inductively coupled plasma mass spectrometry (CVG-ICP-MS) has been developed for determination of inorganic mercury, Hg(II), and total mercury in fish otoliths. Sodium borohydride (NaBH4) was used as the only reducing agent and its concentration was optimized across an acidity gradient to selectively reduce Hg(II) without affecting methylmercury, CH3Hg(I). Inorganic Hg was quantitatively reduced to elemental mercury (Hg) with 1 x 10(-4)% (m/v) NaBH4 center dot CH3Hg(I) required a minimum of 0.5% (m/v) NaBH4 for complete reduction. Increasing the HCl concentration of solution to 5% (v/v) improved the selectivity toward Hg(II0) as it decreased the signals from CH3Hg(I) to baseline levels. Potassium ferricyanide solution was the most effective in eliminating the memory effects of Hg compared with a number of chelating and oxidizing agents, including EDTA, gold chloride, thiourea, cerium ammonium nitrate and 2-mercaptoethylamine chloride. The relative standard deviation (RSD) was less than 5% for 1.0 mu g L-1 Hg(II) solution. The detection limits were 4.2 and 6.4 ng L-1 (ppt) for Hg(II) and total Hg, respectively. Sample dissolution conditions and recoveries were examined with ultra-pure CaCO3 (99.99%) spiked with Hg(II) and CH3HgCl. Methylmercury was stable when dissolution was performed with up to 20% (v/v) HCl at 100 degrees C. Recoveries from spiked solutions were higher than 95% for both Hg(II) and CH3Hg(I). The method was applied to the determination of Hg(II) and total Hg concentrations in the otoliths of red emperor (CRM 22) and Pacific halibut. Total Hg concentration in the otoliths was 0.038 +/- 0.004 mu g g(-1) for the red emperor and 0.021 +/- 0.003 mu g g(-1) for the Pacific halibut. Inorganic Hg accounted for about 25% of total Hg indicating that Hg in the otoliths was predominantly organic mercury (e.g., methylmercury). However, as opposed to the bioaccumulation in tissues, methylmercury levels in otoliths was very low suggesting a different route of uptake, most likely through the deposition of methylmercury available in the water. (C) 2012 Elsevier B.V. All rights reserved.

【 授权许可】

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