PNPP (p-nitrophenyl phosphate, disodium salt) is a widely used substrate for detecting alkaline phosphatase in ELISA applications. When alkaline phosphatase and PNPP are reacted, a yellow water-soluble reaction product is formed. This reaction product absorbs light at 405nm. Pierce PNPP is available in four formats: dry crystalline powder, single-use tablets, a stable substrate solution and a complete kit containing substrate solution and diethanolamine buffer.
Absorbance maximum of 505nm for measurement by ELISA plate readers
Develops a yellow hue in solution upon reaction with alkaline phosphatase (AP)
Safer to use – solution contains a non-mercury, non-azide preservative