Orexin (OX) BioAssay™ ELISA Kit (Mouse) employs the competitive inhibition enzyme immunoassay technique. An antibody specific for Orexin (OX) has been pre-coated onto a microplate. A competitive inhibition reaction is launched between Horseradish Peroxidase (HRP) labeled Orexin (OX) and unlabeled Orexin (OX) (Standards or samples) with the pre-coated antibody specific for Orexin (OX). After incubation the unbound conjugate is washed off. The amount of bound HRP conjugate is reverse proportional to the concentration of Orexin (OX) in the sample. After addition of the substrate solution, the intensity of color developed is reverse proportional to the concentration of Orexin (OX) in the sample.