AOAC GFA Stakeholder Program Meeting Book (March 15, 2023)

4.1.2 Selectivity study Cross Reactivity The matrices identified in Annex A, Table 2, at full, undiluted concentration (with some exceptions as noted), will be prepared and analyzed with the candidate method as it is designed for testing food products. Only if the method’s intended use is limited to environmental surface swabbing should the cross-reactivity study be performed on environmental surfaces. Test one replicate per sample. The method should produce negative results for all samples. In the event that an unclaimed matrix tests positive, it or another example of the same matrix may be retested in six independent test portions (biological replicates), with no positive results, to rule out cross reactivity. Any cross-reactive matrix must be reported to end users as part of the method limitations. All data must be reported, and retests must be explained. I think if oats are not claimed as a target source, then they should be tested in the cross-reactivity panel. I would add the following: “If oats are not claimed as a source for the candidate method, then oats shall be included in the list of matrices in Table 2.” Page 6. – use of term “biological replicate” Suggest modifying as follows: “In the event that the single sample replicate tests negative, it may be retested from the same test material in 20 additional test portions with no additional negative results to rule out interference.”