AOAC ERP Gluten Assays - March 2019

Review of AOAC OMA 2012.01 for Final Action Paul Wehling AOAC Allergen ERP August 13, 2015

General Comment: The method in question was adopted first action in 2012. Since that time, the ERP has adopted several other ELISA methods as first action, and in the process, has made some decisions and established some precedents, which were not applied to this method in 2012. My feeling is this method should be revised to align with those precedents before moving to Final Action. Specific Comments: Title: The title should be more in line with what we have been doing in more recent methods, such as “Gluten in {matrix or matrices} by R5 Sandwich ELISA method” I think it is important to add the R5 and sandwich because we have other methods with other antibodies, and other techniques such as competitive assays. This helps do easily differentiate the methods. Section A. Principle: Wording in 2 nd paragraph – “following an extraction” should be changed to “followed by an extraction.” “is used in a second-step sandwich method..” should be “is used in a 2-step sandwich method.” C. Antibody Characteristics – this whole section should be deleted – in past methods, we have decided that this section is not necessary in an OMA method. Table 2012.01 – some modifications needed: 1) Matrix categories should be more descriptive. In the JAOAC, it says these are breads made from maize and rice – descriptors should say more than “Maize” or “rice”. 2) “Negative samples were not included in the statistical evaluation” - in recent collabs, we have done statistical analyses of the blank samples and used that in the LOD/LOQ calculations. These stats should be included in the table. 3) All results should be expressed in gluten units, not gliadin units. Section F. Preparation of Test Samples “Weigh 5 g sample and grind to a powder as fine as possible to obtain maximal surface.” In this sentence, 5 g is way too small a sample to get a representative sample. The phrase “as fine as possible” is too vague to mean anything – this should be replaced with some type of specific particle size criterion, or be removed. “Dilute the sample at least 1:12.5…” The phrase “at least” is troubling from a calculation standpoint. Are the calculations general enough to accommodate any dilution factor here? Section G. Preparation of Components Delivered with Kit: “Make sure the buffer is not contaminated with gliadin.” How do you do this? Why is contamination only important for this particular buffer?