Optimization and validation of a quick and responsive LC–ESI–MS/MS method to evaluate tetracycline residues in processed animal proteins (PAPs)

Following the bovine spongiform encephalopathy (BSE) in 2001, processed animal proteins (PAPs) reintroduction is envisaged in non-ruminant feed thanks to their high protein content, easy availability and cost-effective characteristics. PAPs must be submitted to rendering practices, providing sterilization of products, under standardized conditions of temperature and pressure, according to Regulation (EC) No 142/2011. However, the chemical risk associated to these raw materials has been never evaluated. The aim of this study was to develop and validate a reliable liquid chromatography tandem mass spectrometry (LC–MS/MS) method for the determination and quantification of tetracycline residues in PAPs at µg kg −1 level. The LC–MS/MS method performances were evaluated in terms of specificity, linearity (25–500 µg kg −1 ), limit of quantitation (LOQ) (25 µg kg −1 ), accuracy and precision (CV% < 25%), uncertainty, recovery (80–120%) and ruggedness. All the evaluated parameters fulfilled the analytical performance criteria, and the validated LC–MS/MS method fits for purpose as confirmatory method on the occurrence of residues (µg kg −1 ) of tetracyclines in PAPs. PAPs are a powerful product which could be used both as raw materials in feed and in organic fertilizer production in a circular economy context. Therefore, the lack of regulation and control over antibiotic occurrence should be implemented to avoid a misuse and an increment of antibiotic resistance pressure over the environment and to ensure safety of the feed and food chain. Graphical Abstract