Control of residues of non-authorized pharmacologically active substance in food of animal origin. Results of a proficiency test for determination of chloramphenicol in honey organized by the Italian National Reference Laboratory for Residues

Chloramphenicol is a non-authorized substance for veterinary treatments. The Commission Regulation (EU) 2019/1871 set a Reference Point of Action (RPA) equal to 0.15 µg/kg in force from 28 November 2022, lowering the Minimum Required Performance Limit set in the Commission Decision 2002/657/CE. A Proficiency testing (PT) for the determination of chloramphenicol in honey was organized by the Italian National Reference Laboratory (NRL) for Residues to check the capability of official laboratories (OfLs) to enforce the new RPA. Six Italian OfLs and five European laboratories joined PT and received a blank and two spiked samples. The reference values (0.17 µg/kg and 0.34 µg/kg) were established as consensus from expert laboratories (the European Union Reference Laboratory and some NRLs). The PT was organized before the enforcement of the new RPA giving the OfLs the chance to test their methods in an early stage. Six participants sent results using both screening and confirmatory methods, two submitted only confirmatory data and three performed exclusively screening analysis. For screening methods all laboratories discriminated between blank and contaminated samples. The z scores were calculated only for confirmatory data and all laboratories got a |z|< 2 corresponding to a satisfactory performance.