ABTS solution is widely used in biochemical and analytical applications as a chromogenic substrate for enzyme-linked assays. It is commonly employed in ELISA (Enzyme-Linked Immunosorbent Assay) procedures where it reacts with peroxidase enzymes, such as horseradish peroxidase (HRP), to produce a stable blue-green colored product that can be measured spectrophotometrically at 405–420 nm. This color change allows for the detection and quantification of specific antigens, antibodies, or other biomolecules. It is also used in antioxidant capacity assays, such as the TEAC (Trolox Equivalent Antioxidant Capacity) method, where ABTS is oxidized to form a stable radical cation. Antioxidants in a sample reduce this radical, leading to a decrease in absorbance proportional to their antioxidant activity. This makes ABTS solution valuable in food science, pharmaceuticals, and biological research for evaluating the radical scavenging potential of compounds. Due to its water solubility and consistent color development, ABTS is preferred in both microplate and solution-based assays where sensitivity and reproducibility are critical.