The preparation of codfish candidate reference material to be certified for Pb, Cd, Hg, Fe, and Zn

Summary Since 1985 the conditioning of fresh seafish muscle reference materials to be certified for trace metals has been studied by CBNM at the request of BCR. This paper describes the study of the production process of a codfish reference material to be certified for Pb, Cd, Hg, Fe and Zn and its subsequent preparation. In particular, the collection of the base material, its transformation into powder by cryo-grinding in all-teflon equipment, the production of dry powder by freeze-drying and the conditioning and bottling of the candidate reference material. Production control and final homogeneity assessment were carried out by solid sampling Zeeman atomic absorption spectrometry. Analyses at different stages in the production process indicate that heterogeneities existing in the starting material are gradually eliminated in the subsequent production stages and that no external contamination occurs.