Used as a substrate in enzymatic assays to measure esterase and lipase activity. The compound is hydrolyzed by these enzymes, releasing p-nitrophenol, which is yellow and can be easily detected spectrophotometrically at around 400–410 nm. This color change allows for real-time monitoring of enzyme activity in both research and diagnostic applications. Commonly employed in studies of enzyme kinetics, inhibition, and purification. Also used in screening microorganisms for lipase production in microbiology and biotechnology. Suitable for use in both solution-based assays and solid media when incorporated into agar plates.