Determination of the Fipronil content in eggs : report on the proficiency test organised by the JRC

This report presents the results of the proficiency test (PT) organised by the European Commission's Joint Research Centre (JRC) - in agreement with DG SANTE - following a request by the Belgium Government on 16/08/2017. The aim of this PT is to to assess the competence of Official Control Laboratories (OCLs) and National Reference Laboratories (NRLs) in the EU Member States for the determination of the content of the insecticide fipronil in eggs around the regulated Maximum Residue Level (MRL). Two well-characterised, homogeneous and stable sets of samples of frozen liquid eggs were prepared and distributed to participants for analysis, in order to evaluate their capability to identify properly non-compliant food commodities. The PT was announced on the JRC website on 22/08/2017. Eighty-five NRLs and OCLs from 22 EU Member States, Norway, Serbia and Albania participated to the exercise. Samples were dispatched to participants on 25-27/09/2017, and the deadline for reporting results was set to 12/10/2017. The liquid egg starting material was purchased from a local supermarket. The material was processed and characterised at the the JRC facilities in Geel. The assigned values for the content of fipronil and fipronil sulfone, respectively (as well as the sum content of these compounds, expressed as fipronil) as well as the corresponding measurement uncertainties have been derived from the gravimetrical formulations, i.e. independently from the participants' results. They were further confirmed by in-house measurements using liquid- or gas chromatography with tandem mass spectrometry. The participants were free to choose their method of analysis. The reported results were evaluated following the procedures of the JRC Unit F.5 - Food and Feed Compliance, which is accredited for the organisation of PTs according to the international standard ISO/IEC 17043:2010. The performance of the participating laboratories in determining fipronil in the test material was expressed as z scores. The vast majority of the participants (94 %) obtained satisfactory z scores, thus confirming the analytical capability of most of the participating NRLs and OCLs to enforce the European Regulations (EC) 396/2005 and 1127/2014 setting maximum residue levels of pesticides (including fipronil) in or on food and feed of plant and animal origin. The laboratories had also to report their measurement uncertainties in μg/kg. It should be noted that 20 laboratories reported seemingly erroneous uncertainties (expressed in %), and that 14 laboratories did not report uncertainties at all. However, 43 % of the participants set their measurement uncertainty to the maximum tolerable uncertainty (of 50 %) recommended for regulatory compliance assessment. 79 participants (out of 85) correctly classified one of the test materials as noncompliant. Most of them provided a proper justification for their compliance statement, while nine of them did not submit a justification.