Ferric reducing ability of plasma (FRAP, also Ferric ion reducing antioxidant power) is an antioxidant capacity assay that uses Trolox as a standard. The FRAP assay was first performed by Iris Benzie and J. J. Strain of the Human Nutrition Research Group at the University of Ulster, Coleraine. The method is based on the formation of O-Phenanthroline-Fe(2+) complex and its disruption in the presence of
chelating agents. This assay is often used to measure the antioxidant capacity of foods, beverages and nutritional supplements containing polyphenols.