AOAC GFA Stakeholder Program Meeting Book (August 27, 2023)

PAGE FIVE – SELECTIVITY STUDY - BREADTH

Breadth The materials identified in Annex A, Table 1, should be tested at three times the LOQ of the method (as long as that is equal to or below 20 mg/kg, otherwise test at 20 mg/kg) in a rice flour matrix. Test six test portions per test material. The absorbance or optical density (OD) values for all test portions and standards must be reported. The extrapolated concentration for all test portions that had an absorbance or OD above the limit of detection of the method must be reported, and the percent recovery should be calculated and reported for each test portion. If any analysis is repeated, both datasets must be reported and a justification given for all repeat analysis. Calculate the mean recovery and 90% confidence interval for each gluten source. Would like similar paragraphs from Gluten Qualitative document starting “The claimed gluten sources…” and “A method claiming wheat…” (Change qualitative language to more appropriate for quanititative.) 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.). Only if the method’s intended use is limited to environmental surface swabbing should this study be performed on environmental surfaces. Analyze one test portion of each prepared test material. The claimed gluten sources (wheat, rye, barley and/or oats) should all produce positive results. In the event that the single test portion tests negative, it may be retested in 20 additional test portions, 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. A method claiming wheat must give a positive response to all listed Triticum species and Triticale, otherwise a claim for the specific Triticum species must be made. For methods claiming any Triticum species, only common wheat ( Triticum aestivum ) should be used in all other studies described in this guidance.