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

4.1.2 Selectivity study Breadth

The gluten source materials identified in Annex A, Table 1, should be tested at two times the lowest CDC (as long as that is equal to or below 20 mg/kg, otherwise test at 20 mg/kg) in a rice flour matrix . Only if the method’s intended use is limited to environmental surface swabbing should this study be performed on environmental surfaces. Test one replicate per sample. The claimed gluten sources (wheat (all Triticum species), rye, barley and/or oats) should all produce positive results. In the event that the single sample replicate tests negative, it may be retested in 20 biological replicates, with no failures allowed, to rule out an insufficient response to that gluten source. All data must be reported, and retests must be explained. Any gluten sources that do not meet these criteria cannot be claimed, and must be reported in the method instructions. Proposed New Text Each gluten source material identified in Annex A, Table 1 must be tested in a rice flour matrix. For claimed gluten sources the test level is two times the CDC (as long as that is equal to or below 20 mg/kg, otherwise test at 20mg/kg) For unclaimed gluten sources the test level is twice the lowest CDC among the claimed gluten sources (as long as that is equal to or below 20 mg/kg, otherwise test at 20mg/kg.) Justification: This edit clarifies the requirement that all the grains listed in Annex A, Table 1 must be tested, and it specifies the levels to test in the case that different gluten sources are claimed at different CDC’s. 2nd paragraph under "Breadth". The sentence top of right column – “The claimed gluten sources (wheat (all Triticum species), rye, barley and/or oats) should all produce positive results.” Is unclear and could be rewritten to avoid confusion. I would recommend the following: “Method developers are free to claim any one or more grains as target species. All claimed gluten sources should produce positive results.” In section 4.1.2, it states that if the single test does not detect gluten, 20 more are performed and none can fail to detect. What is the basis for the 20 replicates? Is it to meet the 95% POD (20/21=95.2%)?