Horseradish peroxidase (HRP) and HRP conjugates facilitate the ABTS oxidation in the presence of hydrogen peroxide, turning ABTS into its blue-green oxidized product. This chromogenic reaction is widely used for quantify HRP in ELISA assays. The oxidized ABTS product has the absorption maximum of 420 nm that can easily be followed with a spectrophotometer. ReadiUse™ ABTS Solution is optimized for ELISA assays that use HRP or HRP-labeled conjugates and hydrogen peroxide in microwell plates or test tubes. Our ABTS solution allows HRP reaction done in a single addition. The assay solution changes its color to light green upon its reaction with HRP or HRP conjugates in the presence of hydrogen peroxide.