– Naphthol AS-TR Phosphate disodium is a water-soluble dye commonly used as an enzymatic substrate in various biochemical assays to detect alkaline phosphatase activity. Naphthol AS-TR Phosphate disodium has unique chemical properties that allow it to be hydrolyzed by alkaline phosphatase, forming a colored product that can be detected spectrophotometrically. This makes it a useful tool for monitoring enzyme activity in biological samples such as serum or urine.