The TMB Liquid Substrate System is widely used in immunoassays, particularly in ELISA (Enzyme-Linked Immunosorbent Assay) procedures. It serves as a chromogenic substrate for detecting horseradish peroxidase (HRP) activity. When HRP is present, it catalyzes the oxidation of TMB, resulting in a color change from colorless to blue. This color change can be measured spectrophotometrically, providing a quantitative assessment of the target analyte. The system is valued for its high sensitivity, low background noise, and compatibility with various detection methods, making it a preferred choice in clinical diagnostics, research laboratories, and biopharmaceutical applications. Additionally, the reaction can be stopped with an acid, turning the solution yellow, which further enhances the ease of measurement.