PNPP (p-nitrophenyl phosphate) is a colorimetric, soluble substrate of alkaline phosphatase for use in ELISA applications. The Pierce™ phosphatase substrate kit contains PNPP tablets and a diethanolamine buffer to yield more than one litre of substrate. 1-Step PNPP is supplied pre-mixed with substrate buffer and is ready to use.

• One-component alkaline phosphatase (AP) substrate
• Absorbance maximum of 405 nm

When alkaline phosphatase and PNPP are reacted, a yellow water-soluble reaction product is formed. This reaction product absorbs light at 405 nm.

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.