Certified reference materials (CRMs 463 and 464) for the quality control of total and methyl mercury determination in tuna fish

Determinations of total mercury and methyl mercury (MeHg) are currently performed by a number of laboratories to control the level of contamination of fish samples, The need to improve the quality control of MeHg in fish has justified the organisation of a series of interlaboratory studies in the frame of the BCR-Programme (now renamed Measurements and Testing Programme) of the European Commission, which were successfully concluded by the certification of total mercury and MeHg in two tuna fish materials (CRMs 463 and 464), these materials were collected in the Adriatic Sea, carefully prepared (controlled freeze-drying) and their homogeneity and stability were verified, This paper presents the certification work performed by 14 laboratories from 8 Member States of the European Union, The certified values for total mercury and MeHg are 2.85 +/- 0.16 mu g/g and 3.04 +/- 0.16 mu g/g (as MeHg(+)) in the CRM 463, and 5.24 +/- 0.10 mu g/g and 5.50 +/- 0.17 mu g/g (as MeHg(+)) in the CRM 464, respectively.