Bovine Progesterone ELISA Kit (A79624) employs the competitive enzyme immunoassay technique for the quantitative measurement of bovine Progesterone in serum, plasma, tissue homogenates, and other biological fluids. The 96-well microtiter plate has been pre-coated with Progesterone antigen. During the incubation, Progesterone present in the samples or standards competes with the fixed amount of immobilized Progesterone for binding sites on the Biotinylated Anti-Progesterone Antibody. The more Progesterone present in a sample or standard, the less Biotinylated Anti-Progesterone Antibody that binds to the plate. Following incubation, unbound Biotinylated Anti-Progesterone Antibody is removed by washing, and an HRP-Streptavidin conjugate is added to the wells and the microtiter plate is incubated. Following incubation and washing, TMB substrate solution is then used to visualize the HRP enzymatic reaction by catalysis to produce a blue-coloured product that changes to yellow after addition of acidic stop solution. The density of yellow is inversely proportional to the amount of Progesterone present in each sample or standard. The concentration of Progesterone can then be calculated by reading the O.D. absorbance at 450nm in a microplate reader and referring to the standard curve.