A detection and confirmation strategy for screening of veterinary drugs in honey by liquid chromatography coupled quadrupole time-of-flight mass spectrometry

A strategy for the quantification and confirmation of 40 multi-class veterinary drugs in honey by QuEChERS (quick, easy, cheap, effective, rugged, and safe) combined with liquid chromatography coupled quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) is described. The veterinary drugs examined belong to four classes: quinolones, sulfonamides, macrolides, and tetracyclines. Before analysis by LC-Q-TOF/MS, the sample was diluted with a solution of Na(2)EDTA-McIlvaine buffer solution (0.1 M, pH = 4), extracted with 5% acetic acid in acetonitrile, and cleaned up with an NH2 sorbent. The average recoveries for the majority of analytes (86.9%), based on matrix-matched external calibration curves, were between 70% and 120%, and there was no significant difference in the recoveries between different honey matrices. The repeatability and reproducibility of the method expressed as the RSDs were less than 20% for all analytes. The data acquired by LC-Q-TOF/MS were cross-referenced with an accurate mass database of veterinary drugs, and the suspected analytes were finally confirmed based on a full product ion library match. Compared with the low-resolution MS technique, obvious advantages were obtained in terms of confirmation and identification by LC-Q-TOF/MS. The applicability of the method was verified by applying it to 12 different honey samples, and ciprofloxacin residue (at 99.7 mu g kg(-1)) was detected in one sample.