Used primarily as a chromogen in immunohistochemistry 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 proteins, antigens, and other targets in tissue samples. Also employed in blotting techniques like Western and dot blots for protein detection. Additionally, it serves as a reagent in biochemical assays to study enzyme activity and oxidative processes. Its application extends to electron microscopy, where it aids in enhancing contrast for detailed imaging of cellular structures.