Report on the 10th inter-laboratory comparison organised by the European Union reference laboratory for polycyclic aromatic hydrocarbons : four marker PAHs in chocolate and cocoa butter

This report presents the results of the tenth inter-laboratory comparison (ILC) organised by the European Union Reference Laboratory for Polycyclic Aromatic Hydrocarbons (EU-RL PAHs) on the determination of the four EU marker PAHs, benz[a]anthracene (BAA), benzo[a]pyrene (BAP), benzo[b]fluoranthene (BBF) and chrysene (CHR), in cocoa products, particularly in plain chocolate and cocoa butter. It was conducted under ISO Standard 17043 accreditation. In agreement with National Reference Laboratories, the test material used in this exercise were commercial products. Participants also received a solution of PAHs in solvent of their choice (either toluene or acetonitrile) with disclosed content for the verification of their instrument calibration. Consensus values were used to benchmark the results reported by participants, as the experience of the analytical community with this analysis scope was considered not sufficient to provide reference values. Both officially nominated National Reference Laboratories (NRLs) and official food control laboratories (OCLs) of the EU Member States were admitted as participants. The participants were free to choose the method of analysis. The performance of the participating laboratories in the determination of the target PAHs in cocoa butter and plain chocolate was expressed by z-scores. Satisfactory performance with regard to z-scores was assigned to about 81 % of the reported results.