Extract-and-inject analysis of veterinary drug residues in catfish and ready-to-eat meats by ultrahigh-performance liquid chromatography – tandem mass spectrometry

Authors: Lehotay, Steven; Lightfield, Alan

Submitted to: Journal of AOAC International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2019
Publication Date: 3/11/2020
Citation: Lehotay, S.J., Lightfield, A.R. 2020. Extract-and-inject analysis of veterinary drug residues in catfish and ready-to-eat meats by ultrahigh-performance liquid chromatography – tandem mass spectrometry. Journal of AOAC International. 103(2): 584-606. https://doi.org/10.1093/jaoacint/qsz036.
DOI: https://doi.org/10.1093/jaoacint/qsz036

Interpretive Summary: Analysis of veterinary drug residues in food animal tissues is an important application for improved food safety and addressing antimicrobial resistance. In this study, validation of a rapid extract-and-inject method of analysis for up to 186 targeted veterinary drugs in hot dogs, catfish, sausage, bacon, and chicken tenders was conducted according to USDA FSIS protocols. Comparison with an alternate method using cleanup of the extracts showed that the rapid method worked as well as the more time-consuming and expensive approach. This new method has been transferred to and implemented by FSIS for routine use in the US National Residue Program, which will save costs of reagents compared with the previous method used.

Technical Abstract: Validated analytical methods are needed to conduct regulatory monitoring of ready-to-eat meats and fish for food safety, risk assessment, and other purposes. The methods should be cost-effective, high-throughput, and meet acceptable performance standards for a wide scope of drugs and matrices. Objective: The goal of this study was to demonstrate the validity for possible implementation in the US National Residue Program of an efficient method for qualitative and quantitative analysis of 176 targeted drugs at levels as low as 10 ng/g in hot dogs, catfish and swai (siluriformes), chicken tenders, fried bacon, and sausage using ultrahigh-performance liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS). Methods: Sample preparation simply involved a 5 min extraction by shaking of 2 g comminuted samples with 10 mL of 4/1 (v/v) acetonitrile/water followed by centrifugation and UHPLC-MS/MS analysis of 2 µL injections. For comparison of results, sausage extracts were also prepared using a cartridge-based EMR-Lipid method with cleanup prior to analysis. Results: Acceptable validation of 70-120% recoveries with <25% RSDs was met for 156-176 out of 186 drugs and quality control analytes without cleanup depending on the matrix. The EMR-Lipid method for sausage improved results for some analytes, such as mectin anthelmintics, due to reduction of indirectly interfering fats in the final extracts, but it also led to significantly worse results for several other drugs, resulting in 32 fewer analytes meeting the given validation criteria than without cleanup. Conclusions: The simple, high-throughput method was demonstrated to be valid to meet routine regulatory and other monitoring needs for many diverse targeted drugs in fish and ready-to-eat meat matrices.