Used primarily as a chromogen in immunohistochemistry and histochemistry for detecting peroxidase activity. It forms a visible brown precipitate when reacting with hydrogen peroxide in the presence of peroxidase, making it valuable for visualizing antigens in tissue samples. Commonly applied in ELISA assays and Western blotting for protein detection. Also utilized in electron microscopy to enhance contrast in biological specimens. Its sensitivity and stability make it a preferred choice in diagnostic and research laboratories for identifying cellular and molecular markers.