Species-specific isotopic analysis of mercury in marine biota: Systematic evaluation of extraction and oxidation methods for a straightforward analytical approach
Vandermeiren, M.; Abou-Zeid, L.; Braeuer, S.; Vanhaecke, F. (2026). Species-specific isotopic analysis of mercury in marine biota: Systematic evaluation of extraction and oxidation methods for a straightforward analytical approach. Talanta 304: 129566. https://dx.doi.org/10.1016/j.talanta.2026.129566
In: Talanta. Elsevier: Amsterdam. ISSN 0039-9140; e-ISSN 1873-3573, more
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| Authors | | Top |
- Vandermeiren, M.
- Abou-Zeid, L.
- Braeuer, S.
- Vanhaecke, F., more
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| Abstract |
Mercury (Hg) is a globally distributed heavy metal with significant environmental and health implications. Along its biogeochemical cycle, Hg can transform into various chemical species, including methylmercury (MeHg), a potent neurotoxin capable of crossing biological barriers, thereby posing serious risks to the human nervous system, especially in fetuses and infants. While determination of the Hg concentration and its speciation analysis already offer valuable insights, isotopic analysis, particularly species-specific isotopic analysis, can reveal detailed information on the environmental pathways and transformation processes of individual Hg species. However, existing approaches for species-specific isotopic analysis techniques, such as an online combination of gas chromatography and multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) or offline separation of Hg species with subsequent MC-ICP-MS analysis, present several challenges and downsides. This study evaluated multiple methods for selective extraction of MeHg from marine biological matrices and for subsequently oxidizing it into Hg2+, thus enabling offline isotopic analysis using cold vapor generation (CVG) coupled to MC-ICP-MS. Three different extraction approaches were evaluated and fine-tuned. One extraction approach, which employed a mixture of NaBr, H2SO4, and CuSO4, followed by extraction in toluene and a final back-extraction of MeHg into the aqueous phase using a solution of Na2S2O3, proved to be the most effective, providing quantitative recovery of MeHg from the matrix. Subsequently, microwave-assisted oxidation using concentrated HNO3 and H2O2 was found to be the most robust and efficient approach, allowing quantitative oxidation of MeHg into Hg2+. The optimized workflow was then applied to (i) three certified reference materials (ERM-CE 464, BCR-414, and TORT-3), for which the results agreed well with previously reported data, and (ii) four fresh samples of marine origin, thus validating the optimized method and highlighting its potential fo |
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