pNPP (p-nitrophenylphosphate) is a chromogenic substrate for Alkaline Phosphatase (AP). In the presence of AP, pNPP is hydrolyzed rapidly to p-nitrophenol and inorganic phosphate. Liberated p-nitrophenol is seen as a clear yellow color that is measured at 405/620 nm. pNPP liquid ready-to-use substrate is highly active compared to pNPP ONE (cat. No. 4401). The substrate gives superior results due to its sensitivity, allowing very low detection limits.

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