Used primarily as a chromogenic substrate in ELISA (Enzyme-Linked Immunosorbent Assay) tests, it facilitates the detection of antibodies or antigens in biological samples. When oxidized, it produces a blue color, which can be measured spectrophotometrically to quantify the presence of specific proteins or pathogens. It is also employed in immunohistochemistry for visualizing cellular components under a microscope. Additionally, it serves as a reagent in various biochemical assays to study enzyme activity, particularly peroxidase enzymes. Its sensitivity and stability make it a preferred choice in diagnostic and research laboratories.