ORAC assay. First, some background.
The ORAC assay is meant for the measurement of antioxidant capacity, in various types of samples like food and biological. A fluorescent indicator and a free radical generator are used together. The radicals produced when the free radical generator is activated damage the indicator, which loses its properties. This can be detected in a fluorimeter as a decrease in the signal.
When you add your sample rich in antioxidants to this mixture, the antioxidants protect the probe, and the decrease in the fluorescence is slowed down.
The measurement is typically done over a long period of time, like one hour and a half, so you can detect antioxidants with different kinetics, the ones that act first and the second ones that act when the first have been depleted, and so on.
After that, you will obtain a plot similar to that attached