Used as a chromogenic substrate in enzyme assays, particularly for thiol group detection. Commonly employed in the Ellman’s reagent system to quantify free sulfhydryl groups in proteins and peptides, producing a yellow-colored compound measurable at 412 nm. Also applied in studies of enzyme kinetics, antioxidant activity, and redox biology due to its reaction with thiol-containing molecules. Its high sensitivity makes it valuable in biochemical and pharmaceutical research for monitoring thiol-disulfide exchange reactions.