Proficiency test for heavy metals in feed and food in Europe

The European Community Reference Laboratory for Heavy Metals in Feed and Food (CRL-HM) coordinated a project, IMEP-103, to compare the concentrations of Cd, Pb and Hg in compound feed when applying total digestion of the matrix and partial extraction (Cd and Pb only) with 5% (w/w) HNO3, as indicated in European Union Directive 2002/32/EC on undesirable substances in animal feed. CRL-HM organized a proficiency-test exercise involving 31 National Reference Laboratories. The main outcome was that the concentrations of Cd after total digestion and after digestion with 5% (w/w) HNO3 were identical. There was evidence of the same outcome for the concentration of Pb, although, due to the heterogeneity of the test material for Pb, no definitive conclusion could be reached for Pb. In this study, CRL-HM used external reference values instead of consensus values, usually derived from the participants’ results.