Development and validation of an LC-MS/MS multi-class method for the determination of 15 different classes of veterinary drug residues in milk and poultry feed

An HPLC-MS/MS multi-class method for quantitation of >15 different classes of veterinary drug residues (>140 analytes) in milk and poultry feed was developed and validated. Accuracy criteria for routine laboratories were met for the majority of analytes, >83 % in milk and between 50 and 60 % in chicken feed, with an apparent recovery of 60–140 %. Extraction efficiency criteria were met for >95 % of the analytes for milk and >80 % for chicken feed. Intermediate precision meets the SANTE criterion of RSD < 20 % for 80–90 % of the analytes in both matrices. For all analytes with an existing MRL in milk, the LOQ was below the related MRL. Twenty-nine samples of commercial milk and chicken feed were analyzed within the interlaboratory comparison#. No residues of veterinary drugs were found in the milk samples. However, the feed samples exhibited high levels of nicarbazin, salinomycin, and decoquinate.