The ORAC assay depends on the free radical damage to a fluorescent probe, such as fluorescein, to result in a downward change of fluorescent intensity [10]. The assumption, of course, is that the degree of change is indicative of the amount of radical damage. The presence of antioxidants results in an inhibition in the free radical damage to the fluorescent compound. This inhibition is observed as a preservation of the fluorescent signal. Reactions containing antioxidants and or blanks are run in parallel using equivalent amounts of a ROS