Multiclass method for antimicrobial residue analysis in milk using liquid chromatography-quadrupole-time of flight-mass spectrometry (LC-qTOF-MS): validation and application for real samples with ciprofloxacin

Abstract

We developed and validated a novel method for screening and confirming 32 antimicrobial residues in raw, bovine milk using a single preparative step. Antimicrobials under the scope of the method belong to different classes, such as fluoroquinolones, tetracyclines, sulfonamides, macrolides and lincosamides. Sample preparation is simple, quick and requires just one extraction process to satisfactorily extract all analytes. Method performance requirements were found to be satisfactory according to the European (EU) Regulation 2021/808, thus confirming the applicability of LC-ESI-QTOF-MS/MS for reliable qualitative and quantitative purposes. Samples from animals undergoing ciprofloxacin treatment were also analyzed, further confirming the method´s fitness-for-purppose. This approach offers a quick and easy way to perform qualitative and quantitative assessment of 32 antimicrobial residues simultaneously, and therefore could be a valuable resource to optimize analytical routines as part of the efforts to help tackling the persistent, global public health silent pandemic of antimicrobial resistance.