The change of alkaline phosphatase activity is involved in a variety of physiological and pathological events, such as bone development, bone-related diseases, gestation-related diseases and inflammatory bowel diseases. Alkaline phosphatase is also a popular enzyme conjugated with secondary antibody for ELISA. p-Nitrophenyl phosphate (pNPP) is proven to be an effective chromogenic substrate for alkaline phosphate. This SensoLyte® kit can be used to detect alkaline phosphatase activity in biological samples and alkaline phosphatase-based ELISA. The kit contains: pNPP chromogenic liquid substrate (absorption maximum = 405 nm upon dephosphorylation), Assay buffer, Stop solution, Alkaline phosphatase standard, “mix and read” assay protocol that is compatible with high throughput screening.