This kit is based on Double antibody-Sandwich ELISA detection method and takes 4h assay time. The microplate provided in this kit has been precoated with anti PEDF antibody. Add standard and properly diluted sample into relevant well respectively. After incubation, wash unbound components. Add biotinylated detection antibody. Then, it binds with PEDF bound to precoated antibody. Wash unbound components and add HRP-Streptavidin Conjugate (SABC). Wash unbound components again and add TMB substrate solution. Then, TMB was catalyzed by HRP to produce a blue color product that turned yellow after adding a stop solution. Read the O.D. absorbance at 450nm in a microplate reader. Calculate the concentration of PEDF in the sample by plotting standard curve. The concentration of the target substance is proportional to the OD450 value.