ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Mercury speciation in fish tissue by eco-scale thermal decomposition atomic absorption spectrometry: method validation and risk exposure to methylmercury

Marin Senila, Eniko Covaci, Oana Cadar, Michaela Ponta, Maria Frentiu, and Tiberiu Frentiu

INCDO-INOE2000, Research Institute for Analytical Instrumentation, Cluj-Napoca, Romania

E-mail: marinsen@yahoo.com

Abstract: A non-chromatographic method for Hg speciation in fish muscle using eco-scale thermal desorption atomic absorption spectrometry was validated according to the demands of the Decisions 2007/333/EC, 2011/836/EC and 2002/657/EC. The method is based on the determination of total Hg in solid sample and MeHg⁺, respectively, after double liquid–liquid extraction (47% HBr, toluene, 1% l-cysteine) according to a procedure recommended by the European Commission. The method was applied for the speciation of Hg in fish muscle to asses the weekly intake and health risk exposure to MeHg⁺. The method provided calibration coefficients better than 0.999, limits of detection of 0.2 µg kg⁻¹ total Hg and 3.0 µg kg⁻¹ MeHg⁺. The accuracy of the method assessed by the analysis of CRMs was 100 ± 9% for total Hg and 101 ± 13% for MeHg⁺ for a coverage factor k = 2. The figures of merit of the method comply with the requirements in the European legislation. Total Hg in the analyzed fish species was in the range 12–108 µg kg⁻¹ wet mass, of which 83–97% as MeHg⁺. Although significant variation in total Hg was observed among fish species, no differences in terms of distribution of organic and inorganic Hg species were identified. No risk exposure to MeHg⁺ was ascertained from muscle fish consumption from reliable sources, since weekly intake was below 30% of provisional tolerable weekly intake of 1.6 µg kg⁻¹ body weight. Speciation is recommended as MeHg⁺ is much more helpful than total Hg to evaluate the dietary risk exposure.

Keywords: Mercury speciation ; Thermal decomposition atomic absorption spectrometry ; Method validation ; Methylmercury risk exposure 

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-017-0296-3

Chemical Papers 72 (2) 441–448 (2018)