evidence: The Environmental Protection Agency (EPA) establishes tolerances for pesticide and herbicide residues in food that are still considered safe for consumption. For food manufacturers to test their products a reference material is recommended to ensure their measurements are accurate. Oats are of particular interest as the herbicide, glyphosate, is used as a desiccant to dry out the crop before harvest. This allows for earlier harvests and greater uniformity of crops. Consequently, glyphosate is typically found at higher levels than other herbicides. The reference materials are oat flour obtained from commercial sources. The level of glyphosate in the RM 8238 (high level) was targeted to represent typical glyphosate levels found in oats from conventional agriculture practices. The level of glyphosate in RM 8239 (low level) was targeted to represent typical glyphosate levels found in oats from organic agriculture practices, yet high enough to detect by current glyphosate analytical methods These materials are intended for harmonizing measurements of glyphosate in grains and similar materials.