Submitted to: Journal of Chromatography A
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/5/2012
Publication Date: 10/5/2012
Citation: Geis-Asteggiante, L., Lehotay, S.J., Lightfield, A.R., Dutko, T., Ng, C., Bluhm, L. 2012. Ruggedness testing and validation of a practical analytical method for > 100 veterinary drug residues in bovine muscle by ultrahigh performance liquid chromatography – tandem mass spectrometry. Journal of Chromatography A. 1258:43-54. Interpretive Summary: In the National Residue Program, the USDA Food Safety Inspection Service (FSIS) currently uses a bioassay for lab-based screening that 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 previously transferred to FSIS an analytical screening method for 62 drugs to replace the bioassay screen with ultrahigh performance liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS). Now we have further expanded and tested the screen for 127 drugs in beef. We optimized, evaluated, and extensively validated the method, which was transferred to the FSIS Midwestern Laboratory where it will be implemented in the future. This UHPLC-MS/MS approach allows FSIS to further improve its monitoring capabilities for better food safety and regulatory activities.
Technical Abstract: In this study, optimization, extension, and validation of a streamlined, qualitative and quantitative multiclass, multiresidue method was conducted to monitor great than100 veterinary drug residues in meat using ultrahigh-performance liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS). Instrument performance is a critical factor for routine analysis, optimization centered on extensive ruggedness evaluation of the method. Various clean-up sorbents were tested and the amount of co-extractives were weighed, matrix effects were measured using post-column infusion of representative analytes, the effect of extract dilution before injecting was studied, and analyte recoveries and reproducibilities were determined. As more drug analytes were added that possessed a wider range of chemical properties, a re-appraisal of different types of C18 in dispersive solid-phase extraction clean-up and mobile phases in UHPLC-MS/MS was done. Ultimately, end-capped C18 and post-column infusion of ammonium formate as an ionization enhancer for the late-eluting anthelmintics were found to give improved qualitative results for greater analytical scope. A multi-day, multi-analyst validation demonstrated that the final method is suitable for screening purposes of 113 analytes, identification of 98 and quantification of 87 of the 127 tested drugs at or below US regulatory tolerance levels in bovine muscle.