Veratox for Egg Allergen is a sandwich enzyme-linked immunosorbent assay (S-ELISA). Egg protein residue is extracted from samples with a buffered salt solution (Phosphate Buffered Saline, or PBS) by shaking in a heated water bath, followed by centrifugation or filtration. Extracted egg protein is sampled and added to antibody coated wells (capture antibody) where it binds to the antibody during an incubation. Any unbound protein is washed away and a second antibody (detector antibody), which is enzyme labeled, is added. The detector antibody binds to the already bound egg protein. After a second wash, the substrate is added. Color develops as a result of the presence of bound detector antibody. Red Stop reagent is added and the color of the resulting solution is observed. The test is read in a microwell reader to yield optical densities. The optical densities of the controls form a standard curve, and the sample optical densities are plotted against the curve to calculate the exact concentration of egg allergen.