This Human Apolipoprotein D ELISA Kit applies a technique called quantitative sandwich immunoassay. The microtiter plate provided in this kit has been pre-coated with a monoclonal antibody specific for Apolipoprotein D. Standards or samples are then added to the appropriate microtiter plate wells and incubated. Apolipoprotein D if present, will bind and become immobilized by the antibody pre-coated on the wells. The microtiter plate wells are thoroughly washed to remove any unbound Apolipoprotein D and other components of the sample. A biotinylated Anti-Apolipoprotein D detection antibody is then added followed by Streptavidin-HRP. Addition of TMB substrate will result in a colored substrate product. The reaction is stopped with sulfuric acid and the optical density can be quantified using an ELISA plate reader. The concentration of analyte is determined by comparison to a serial dilution of the ELISA standard in parallel.