IMEP-117, determination of total As, Cd, Pb, and Hg in compound feed : interlaboratory comparison report

The Institute for Reference Materials and Measurements of the Joint Research Centre, a Directorate General of the European Commission, operates the European Union Reference Laboratory for Heavy Metals in Feed and Food. One of its core tasks is to organize interlaboratory comparisons among appointed National Reference Laboratories. This report presents the results of a proficiency test, IMEP-117 of the EURL-HM which focused on the determination of total As, Cd, Pb and Hg in compound feed in support to Directive 2002/32/EC of the European Parliament and of the Council on undesirable substances in animal feed. The test material used in this exercise was a commercially available compound feed for cats which was spiked after the appropriate processing, bottled, labelled, and dispatched to the participants on the 23rd of May 2013. Three laboratories with demonstrated experience in the field provided results to establish the assigned values (Xref). The standard uncertainties associated to the assigned values (uref) were calculated according to ISO/IEC Guide 98:2008 (GUM) and ISO 13528:2005. Laboratory results were rated with z- and zeta (ζ-) scores in accordance with ISO 13528:2005. The standard deviation for proficiency assessment (σp), also called target standard deviation, was set to 10 % of the assigned value, for the measurands investigated. The percentage of satisfactory z-scores was above 79 % for all measurands showing an overall adequate performance for European National Reference Laboratories assuring compliance towards the European legislation related to the determination of the investigated compound feed contaminants.