Total and methylmercury in tuna fish
The candidate reference material was collected in the Adriatic sea; it was produced from tuna fishes that were rejected from normal trade because their total mercury content exceeded 0.8 µg/g.
302 kg of tuna fish was sliced, frozen (-25 °C) and transported to Ecoconsult in Gravirate. The rorsal fish muscles were minced using a Quick Mill 2300 mincer with tungsten carbide blades. After mincing, the material obtained was stored frozen in high density polyethylene contgainers. The materials was then freeze-dried ungtil reachinh a moisture mass fraction below 2.5 %. The resulting material (ca. 36 kg candidate CRM) was immedeately frozen.
The freeze-dried material was sent to the JRC of Ispra where it was ground using a mill equipped with zirconium dioxide balls. The ground material was sieved using a vibrating stainless steel sieve. The fractions with particles larger than 125 µm were disgarded and the remaining material was stored in polyethylene boxes in an argon atmosphere. The material was then homogenized in a mixing drum for 16 days and bottled in brown borosilicate glass bottles. A total of 1000 bottles each containing ca. 15 g of material was produced.
keywords: biological material , animal tissue , foodstuff , fish/shellfish , trace elements , speciation analysis , mercury speciation