Determination of 62 veterinary drugs in feedingstuffs by novel pressurized liquid extraction methods and LC-MS/MS.

A fast and simple method for the determination of 62 veterinary drugs in feedingstuffs was developed, optimized, validated, and applied to real samples. Sample preparation was based on a pressurized liquid extraction method using a hard cap coffee machine, which was compared to a commercial pressurized liquid extraction system. Extraction was performed with diatomaceous earth, acetonitrile (20%), and formic acid (0.1%). A central composite design was used to optimize the composition of the extraction solvent. The extracts were analyzed using two chromatographic modes (reversed phase with C18 and HILIC). Analytical limits were set to 25 (limit of detection) and 75 µg kg-1 (limit of quantitation). For banned substances, a salting-out step was included, achieving LOQ lower as 1 µg kg-1 for ractopamine. Other figures of merit such as precision, trueness, decision limit (CCα), method capability (CCβ), matrix effects, stability, recovery, and measurement uncertainty were also reported for analytical validation. The method was successfully applied to hundreds of real samples demonstrating its fitness-for-purpose for the analysis of sulfonamides, tetracyclines, fluoroquinolones, avermectins, quinolones, beta-agonists, beta-lactams, amphenicols, benzimidazoles, coccidiostats, lincosamides, macrolides, nitrofurans, quinoxalines, melamine, and trimethoprim.