CERTIFIED REFERENCE MATERIALS (CRM-463 AND CMR-464) FOR THE QUALITY-CONTROL OF TOTAL AND METHYL MERCURY DETERMINATION IN TUNA FISH

Determinations of total mercury and methyl mercury (MeHg) are currentl y performed by a number of laboratories to control the level of contam ination of fish samples, The need to improve the quality control of Me Hg in fish has justified the organisation of a series of interlaborato ry studies in the frame of the BCR-Programme (now renamed Measurements and Testing Programme) of the European Commission, which were success fully 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) an d their homogeneity and stability were verified, This paper presents t he certification work performed by 14 laboratories from 8 Member State s of the European Union, The certified values for total mercury and Me Hg are 2.85 +/- 0.16 mu g/g and 3.04 +/- 0.16 mu g/g (as MeHg(+)) in t he 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.