Feed premix: a difficult matrix for the accurate determination of trace elements – the outcome of IMEP-114 and IMEP-36

This paper presents the outcome of two proficiency tests (IMEP-114/36) running in parallel, which focused on the determination of total As, Cd, Pb, Hg and Sn in feed premixes. Both exercises aimed to test the performance of laboratories measuring trace elements in feed, in compliance with Directive 2002/32/EC of the European Parliament and of the Council on undesirable substances in animal feed. IMEP-114 was run for the European Union National Reference Laboratories, while IMEP-36 was open to all food control laboratories that wished to participate. In total 80 laboratories from 37 countries registered to both proficiency tests, from which 75 laboratories reported results. The test material used in this exercise was commercially available feed premix, which was processed, bottled, labelled and dispatched to participants. The performance of the participating laboratories was similar in both proficiency tests and was very good in the case of total Cd and less satisfactory for total As and total Pb. For tota...