A CRL–IRMM joint proficiency test for trace elements in fish tissue

Abstract

The Community Reference Laboratory (CRL) for residues and contaminants in food of animal origin at the Istituto Superiore di Sanità (ISS) plans and undertakes on a regular basis Proficiency Tests Schemes (PTSs) focused on the residues under its responsibility, as prescribed by the Council Directive 96/23/EC of April 29, 1996. In consideration of the benefits ensuing from a constant monitoring of the daily activities of the National Reference Laboratories (NRLs) for residues in the Member States, the ISS–CRL frequently prepares test materials to promote comparability of data and support harmonisation of routine analytical procedures. When target values for the analytes are set, the PTSs also provide objective assessment and improvement of the analytical trueness in the daily work. In this context, an interlaboratory comparison for trace elements in tuna fish matrix was organised in cooperation with the Institute for Reference Materials and Measurements (IRMM), Joint Research Centre, European Commission. Freeze-dried tuna fish samples were sent out to the NRLs for chemical elements in the Member States. Participants were requested to carry out at least three independent measurements of the elements As, Cd, Cr, Cu, Fe, Hg, Pb and Zn. The assessment of the proficiency was based on the z-score approach and a relative bias better than or equal to 10% of the target value was deemed to be an acceptable performance for this kind of measurements. On this basis, more than 50% of the laboratories returned accurate results for As, Cu, Fe, Hg and Zn, whereas the analysis of Cd, Cr and Pb appeared to be more problematic.