Report of the Eighth Interlaboratory Comparison organised by the Community Reference Laboratory for Heavy Metals in Feed and Food - Total Cd, Pb, As, Hg and Sn and extractable Cd and Pb in Feed of Plant Origin

Abstract

The Institute for Reference Materials and Measurements (IRMM)of the Joint Research Centre, a Directorate General of the European Commission, operates the Community Reference Laboratory for Heavy Metals in Feed and Food (CRL-HM). One of its core tasks is to organise interlaboratory comparisons (ILCs) among appointed National Reference Laboratories (NRLs). This report presents the results of the eighth ILC of the CRL-HM which focused on the determination of total Cd, Pb, As, Hg and Sn and extractable amounts of Cd and Pb in feed of plant origin following 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 candidate reference material, the matrix being rye grass. The material was relabelled and dispatched to the participants on the second half of October 2009. Each participant received approximately 10 g of test material. Thirty participants from 25 member states registered to the exercise of which 27 reported results for total Cd, Pb and Hg, 23 for extractable Pb, 22 for extractable Cd and for total As and 16 for total Sn. One laboratory did not report results due to a breakdown of the instrumentation, and one laboratory reported results only for Hg for the same reason. The assigned values (Xref) for total Cd, Pb, As, Hg and Sn were the candidate certified values as obtained during the certification. The assigned values for extractable Cd and Pb were provided by IRMM using isotope dilution-inductively coupled plass-mass spectrometry (ID-ICP-MS). Participants were invited to report the uncertainty of their measurements, which was provided by the majority of them. The laboratory performance was evaluated using z- end zeta-scores in accordance with ISO 13528. The standard deviation for proficiency assessment (also called target standard deviation), was fixed to 15% of the assigned values for all measurands on the basis of the outcome of previous ILCs organis.