Organomercury determination in biological reference materials: Application to a study on mercury speciation in marine mammals off the Faröe Islands

The potential use of graphite furnace atomic absorption spectrometry (GF-AAS) for the organic mercury determination in marine biological tissues was evaluated. Following its isolation by acid extraction in toluene, organic mercury was recovered in aqueous thiosulfate and measured by GF-AAS. The detection limit was 0.01 μg Hg/g (as methyl mercury). Analyses were conducted on three reference standard materials certified for their methyl mercury content, DOLT-1, DORM-1, and TORT-1, provided by the National Research Council of Canada. The method resulted in very good recovery and reproducibility, indicating that GF-AAS can provide results comparable to those obtained by using more expensive and time consuming analytical techniques. The method was applied to the analysis of liver tissues of pilot whale specimens (Globicephala melas) from the drive fishery of the Faröe Islands (northeast Atlantic). The results provided useful information on the proportion of different mercury forms in the liver of these marine mammals.