Reference values of methyl mercury mass fractions in new type of environmental matrix-matching materials for speciation analysis assigned by species-specific isotope dilution inductively coupled plasma mass spectrometry and high-performance liquid chromatography

Reference measurements for methyl mercury in four new type of environmental matrix-matching certified reference materials (CRMs) were performed and values of methyl mercury mass fractions were assigned. Hyphenated technique high-performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP-MS) was applied. To ensure the highest metrological quality, species-specific isotope dilution mass spectrometry (SS-IDMS) as primary method of measurements was evaluated. SI-traceable and accurate reference measurements of methyl mercury contents in environmental origin materials: river bottom sediment (M-2 BotSed), herring tissue (M-3 HerTis), cormorant tissue (M-4 CormTis) and codfish tissue (M-5 CodTis) are straightforward related to units of the mol and the kilogram. Results for MeHg (as Hg) obtained by two pair of isotopes: n(200Hg)/n(201Hg) ratio and n(202Hg)/n(201Hg) ratio, excellent agreed within calculated expanded uncertainty and were found to be (as Hg) (C ± UC (UC%)): (15.6 ± 1.0) μg kg−1 (6.4%) in M-2 BotSed, (216 ± 6) μg kg−1 (2.8%) in M-3 HerTis, (2106 ± 54) μg kg−1 (2.6%) in M-4 CormTis and (294 ± 8) μg kg−1 (2.7%) in M-5 CodTis. These data are particularly important in point of speciation analysis requirements, due to high toxicity of methyl mercury and its harmful effects on human health and entire ecosystem. Moreover, as there is still a noticeable lack of CRMs, it is necessary to introduce matrix-matching CRMs related to methyl mercury content in environmental samples for the quality control, monitoring study and risks assessment. As fishes and cormorant are bioindicators of methyl mercury contamination and sediments are pollution indicators, assigned reference values in appropriate CRMs provide unique matrix fit for the research purpose.