Used primarily as a chromogen in immunohistochemistry and enzyme immunoassays, especially in detection systems involving horseradish peroxidase (HRP). When exposed to HRP and hydrogen peroxide, it produces a brown precipitate at the reaction site, allowing visualization of antigen-antibody interactions in tissue sections or on membranes. Commonly applied in Western blotting, ELISA, and immunostaining of cells and tissues. Its high sensitivity and distinct color development make it valuable for precise localization of proteins in research and diagnostic pathology. Due to potential carcinogenicity, handling requires strict safety precautions.