Submitted to: Drug Testing and Analysis Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2012
Publication Date: 8/1/2012
Citation: Lehotay, S.J., Lightfield, A.R., Geis-Asteggiante, L., Schneider, M.J., Dutko, T., Ng, C., Bluhm, L., Mastovska, K. 2012. Development and validation of a streamlined method designed to detech residues of 62 veterinary drugs in bovine kidney using ultrahigh performance liquid chromatography - tandem mass spectrometry. Drug Testing and Analysis Journal. 4:75-90. Interpretive Summary: In the National Residue Program, the USDA Food Safety Inspection Service (FSIS) currently uses a 7-plate microbial inhibition bioassay to screen for illegal levels of antimicrobial drug residues in slaughtered food animals. This bioassay is very limited in the scope of drugs that can be monitored, it is insensitive to many important drugs, it cannot distinguish mixtures or one drug from another in the same class, and it takes 24 hours to obtain results. We proposed to modernize the FSIS monitoring program by replacing the bioassay screen with ultrahigh performance liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS), which overcomes the many bioassay disadvantages by providing greater analytical scope, sensitivity, selectivity, and speed. We developed, evaluated, and extensively validated the method, which was transferred to the FSIS Midwestern Laboratory where it is being implemented. This UHPLC-MS/MS approach allows FSIS to make major improvements in the capabilities of the National Residue Program and increase laboratory efficiency at the same time.
Technical Abstract: In the USA, the US Department of Agriculture’s Food Safety Inspection Service (FSIS) conducts the National Residue Program designed to monitor veterinary drug and other chemical residues in beef and other slaughtered food animals. Currently, FSIS uses a 7-plate bioassay in the laboratory to screen for antimicrobial drugs in bovine kidneys from those animals tested positive by inspectors in the slaughter establishments. The microbial inhibition bioassay has several limitations in terms of monitoring scope, sensitivity, selectivity, and analysis time. Ultrahigh performance liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS) has many advantages over the bioassay for this application, and this study was designed to develop, evaluate, and validate a fast UHPLC-MS/MS method for antibiotics and other high priority veterinary drugs in bovine kidney. Five existing multiclass, multiresidue methods from the literature were tested and compared, and each performed similarly. Experiments with incurred samples demonstrated that a 5 min shake of 2 g homogenized kidney with 10 mL of 4/1 acetonitrile/water followed by simultaneous cleanup of the initial extract with 0.5 g C18 and 10 mL hexane gave a fast, simple, and effective sample preparation method for the less than10 min UHPLC-MS/MS analysis. An extensive 5-day validation process demonstrated that the final method could be used to acceptably screen for 54 of the 62 drugs tested, and 48 of those met qualitative MS identification criteria at the desired concentrations. Quantification was not needed in the application, but the method gave greater than70% recoveries and less than25% reproducibilities for 30 of the drugs.