2019 Vet Drug Residues ERP - Review Book

6. Based on the supporting information, what are the cons/weaknesses of the method?

Because each sample is analyzed with 4-5 different method streams and is analyzed at least twice (fortified and unfortified), the number of analyses required for each sample is fairly high (N=10/sample plus any QC samples for each batch) and may prevent optimum sample efficiency. Although the different method streams described ensure a thorough investigation of each sample for the 154 drug residues, a more universal, generic screening procedure would be more practical for many laboratories. With a screening method, it is not necessary to optimize extraction efficiencies and linearity. Rather, it is just important to establish reproducible detection and identification for the residues at the levels of concern. As such, a more generic extraction and instrumental method might have been sufficient. Although it may always be necessary to treat the aminoglycosides separately, it may have been possible to include β -lactams and tetracyclines in the “multi-family” method stream. An increase in work-flow efficiencies may be worth the loss in method performance for these analytes if there are still adequately detected for screening purposes. The MS data as presented does not support established identification criteria (EU, FDA). Although this may not be required for a screening procedure, ion ratios were requested as part of the SMPR validation guidance. In the peer- reviewed articles, the method authors did provide a rationale for not including ion ratios in their criteria (to minimize false negative rates). However, performing additional data analysis to determine if established identification criteria are met would make the method more applicable to a wider variety of laboratories including regulatory agencies. I would concur that the suite of methods submitted in response to this SMPR should move forward as a First Action Official Method. The methods are logical and well documented and would be of value to many working with the analysis of veterinary drugs. However, I also think that other multi-analyte veterinary drug methods will still be of value to the community because the methods submitted here do not cover all analytes or matrices of interest. Also, if sample through-put is a priority, using several separate analytical method streams is also not as efficient as more generic, universal multi-residue veterinary drug methods currently available. I believe that this method should be adopted as First Action and published in the Official Methods of Analysis of AOAC International. The methods submitted generally meet the requirements specified in the 2019.010 SMPR. Because of the number of method streams, any new matrix would require a great deal of additional validation.

7. Any general comments about the method?

V. Final Recommendation Do you recommend this method be adopted as a First Action and published in the Official Methods of Analysis of AOAC INTERNATIONAL? Please specify rationale.