[Inspection of Residual Veterinary Drugs at Tokyo Metropolitan Institute of Public Health: Bioassay and LC-MS/MS Analysis].

Veterinary drugs are used worldwide to prevent and treat diseases and promote growth in animals, fisheries, and beekeeping. Despite their effectiveness, the illegal and improper use of these drugs can result in livestock and fishery products, potentially impacting human health by causing allergic reactions, cytotoxicity, and antimicrobial resistance. To mitigate these adverse effects, the Japanese government established a positive list system in 2006. Maximum residue levels (MRLs) have been defined for approximately 300 veterinary drugs. The regulation of certain antimicrobial drugs without defined MRLs uses in zero tolerance. Residual veterinary drugs in meat, fish, eggs, milk, and honey are inspected to ensure compliance with legal limits. Initially, samples are screened using bioassay and LC-MS/MS. If residues are detected, they are confirmed and quantified using more precise methods. We have detailed the detection of residual norfloxacin in honey. Additionally, we are currently developing new analytical methods. This study introduces an analytical method for the residue screening of sulfonamides and quinolones. After residue detection by bioassay, the same test solutions were analyzed by LC-MS/MS for accurate identification and quantification. This method has also proven to be more environmentally friendly compared to other quantitative methods. We present the ingenuity used to realize the combined method, performance evaluation results, examples of applications to actual samples, and future prospects.