How should we proceed with the standardization in case of allergen determination?

Allergens cannot at present be measured with the trueness that attends the analysis of well-characterized chemical entities such as mycotoxins where the analytes are defined and identical in sample and calibrator. By nature, allergens are nearly always a mixture of different proteins with different mass fractions of each single protein. Allergens are furthermore in a commodity with different total protein contents in the presence of an unknown matrix. To circumvent these difficulties, reference materials for allergens would be useful but until now not realized due to biological variabilities of the materials, and the contradiction between medical issues and declaration of foods due to legislation. Examples for standardization efforts are given which are (1) peanut where a common reference material not intended for allergen determination is used and (2) gluten/gliadin where the extraction procedure, the antibody and a calibrator are standardized but proficiency tests are not fit-for-purpose due to inhomogeneity of the testing material. Furthermore, the analytical minimum requirements and the declaration of egg-white proteins, caseins and lysozyme in wine are reviewed. To show one negative example for standardization efforts, milk is discussed. The possibilities and limits of reference materials for the standardization of allergen determinations are discussed.