Proficiency testing as an instrument to assess the analytical performance and the methods routinely implemented: the Italian experience for the screening of antibiotic residues in milk in the official control

• DOI: 10.1007/s00769-018-1352-6
• Publication Date: 2018-11-08T20:57:16Z
• Authors: Anna Maria Ferrini; Brunella Appiccia...; Maria Rosa Massaro; Fabio Galati; Marina Patriarca
• Keywords: 0403 veterinary science; 04 agricultural and veterinary sciences

The present work describes the outcome of the second proficiency test (PT) for the routine screening of antibiotic residues in milk, organized in 2016, for the Official Control Laboratories by the National Reference Laboratory (NRL) for veterinary antimicrobial residues in food of animal origin (ISS, Italy). Besides assessing the overall laboratories’ performance, this PT aimed to update the information concerning the screening methods used at the national level and focused, in particular, on the Official Control Laboratories performance for the detection of tetracyclines. This last feature intended to tackle the strong criticalities observed in the first PT, organized by the NRL in 2012, and to monitor the consequent implementation of relevant corrective actions. Thirty-one Official Control Laboratories joined the 2016 PT. They received five lyophilized milk samples, one negative and four positive for benzylpenicillin (PEN), sulphadiazine (SDZ) and oxytetracycline (OXY) to be reconstituted to the final concentrations of 1×MRL for PEN and SDZ and 2.5× and 4×MRL, respectively, for OXY. In addition, only for OXY, the protocol required the preparation by dilution of two additional samples at the final concentrations of 2× and 1×MRL. Overall the laboratories’ performance was satisfactory. However, for OXY, although a reduction in the percentage of false negative results was observed, as compared to the first PT, the majority of laboratories had not yet implemented complementary methods to respond to the criticality previously signalled. One more time the organization of a dedicated PT proved to be an effective means to provide objective indicators of the state of the art in a specific area of testing.