The process begins by incubating a known concentration of labeled antigen with the sample containing an unknown amount of the same antigen. This mixture is then added to a microplate well that has been pre-coated with the specific antibody. After an incubation period, any unbound antigen is washed away. The bound labeled antigen is then detected using a substrate that produces a colorimetric change. The intensity of the color is measured and compared to a standard curve to determine the concentration of the antigen in the sample.
