Proficiency of European National Reference Laboratories in the determination of authorised vitamins in animal feed. EURL for Feed Additives Control PT exercise 2016 and annual workshop.

The European Union Reference Laboratory for Feed Additives (EURL-FA), hosted by the Joint Research Centre (JRC), a Directorate General of the European Commission, has been mandated by the Directorate General for Health and Food Safety (DG SANTE) to organise a proficiency test (PT) among appointed National Reference Laboratories (NRLs) in the frame of its control activities (according to the Regulation (EC) No 882/2004 [1]). The aim of this PT was to assess the capacity of the NRLs to correctly determine selected authorised vitamins added to feed matrices at realistic levels. Twenty-eight European National and Official Control laboratories were invited and eleven laboratories registered to the 2016 PT exercise. The eleven registered laboratories reported results for the analyses. The test items used in this exercise were produced by the EURL-FA Control by milling purchased commercial poultry compound feed containing vitamin A and vitamin E, homogenising and assessing the mass content versus the declared mass content on the label. Each laboratory received one test item. Laboratories were informed of the composition of the test material regarding vitamins and the label provided information on the mass content range to be expected for each vitamin as well as the additive code as specified in the European Union register of feed additives [2]. The assigned values (xa) for the mass content of vitamin A and vitamin E in the samples were established by calculating the robust mean of the measurements performed by the EURL-FA Control and the sub-group of participants who applied the protocol specified in Annex IV of Commission Regulation (EC) No 152/2009 [3] and that were accredited according to ISO 17025:2005 [4] for this protocol. For the uncertainties of the assigned values (Ua), the associated expanded uncertainty (coverage factor k=2) was derived from the robust standard error on the measurements performed by the EURL-FA Control and the sub-group defined above and the between-sample standard deviation of the results obtained during the homogeneity study, calculated using ANOVA. Participants were invited to report the uncertainties of their measurements for completeness of result reporting. This was done by ten out of eleven participants. Laboratory results were rated using z-scores in accordance with ISO 13528:2015 [5]. The standard deviation for proficiency assessment (σp) for each assigned value was set beforehand applying the modified Horwitz equation [6] to the content determined during the homogeneity study performed at the EURL-FA Control. The z-scores obtained were considered satisfactory if their absolute values were equal to or below 2. The outcome of the PT exercise is satisfactory; the percentage of satisfactory results reported by the laboratories is 91% for vitamin A and 91% for vitamin E, respectively.JRC.F.5-Food and Feed Complianc