pNPP Microwell Substrate System

  • Size

    500 mL

  • List Price


  • Unit


  • Inventory Status

    In Stock

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Substrate that contains para-nitrophenylphosphate (pNPP). Designed for use with alkaline phosphatase-labeled conjugates. It develops a yellow color measurable between 405-410 nm. Substrate reaction can be stopped with an equal volume of APStop Solution.

Recommended for ELISA applications. Available as a kit containing 5 mg tablets of pNPP and 5M Diethanolamine (DEA) Buffer Concentrate.

Product Highlights:

  • Reliable substrate for detection of alkaline phosphatase (AP) conjugates
  • Economical choice when high sensitivity is not critical
  • Easy preparation


  • Detection Method: Colorimetric ELISA
  • Measurement: 405 - 410 nm
  • Stability: 1 year from date of receipt
  • Storage: 2 - 8 degrees C

Comparison of AP Colorimetric Substrates for ELISA


Human IgG was serially diluted in an ELISA plate and detected with Anti-Human IgG labeled with AP.  KPL's substrates, BluePhos®, FirePhos™, pNPP, and a competitor pNPP were added to the plate. The reactions were stopped with APStop™ Solution and read at the recommended wavelength for each substrate.