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

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• 作者：Erdal Kenduzler^a ; ¹ ; Mehmet Ates^a ; Zikri Arslan^a ; ^{zikri.arslan@jsums.edu} ; ^{zikriarslan@gmail.com} ; Melanie McHenry^b ; Paul B. Tchounwou^b
• 关键词：Fish otolith ; Inorganic mercury ; Total mercury ; Cold vapor generation ; ICP-MS
• 刊名：Talanta
• 出版年：2012
• 期刊代码：106_00399140
• 类别：ch
• 出版时间：15 May, 2012
• 卷：93
• 期：Complete
• 页码：404-410
• 文件大小：447 K

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 (Hg⁰) with 1 脳 10^鈭?%(m/v) NaBH₄. 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(II) 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 渭g L^鈭? Hg(II) solution. The detection limits were 4.2 and 6.4 ng L^鈭? (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 掳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 卤 0.004 渭g g^鈭? for the red emperor and 0.021 卤 0.003 渭g g^鈭? 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.