pNPP - Ready-to-use (RTU)

Cat. No.: P494193

GRADE & PURITY Ready-to-use (RTU)

Storage

Store at 2-8°C,Protected from light

Shipped In

Wet ice

Overview

Product Characteristics 

pNPP (p-nitrophenylphosphate) is a chromogenic substrate for Alkaline Phosphatase (AP). In the presence of AP, pNPP is hydrolyzed rapidly to pnitrophenol and inorganic phosphate. Liberated pnitrophenol 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. P494181). The substrate gives superior results due to its sensitivity, allowing very low detection limits.

Composition & Properties 

pNPP is a liquid, ready-to-use and aqueous formulation. The buffer solution contains stabilized pNPP and appropriate stabilizing components. Recommended stop solution is an equal volume of 0.1 M sodium hydroxide solution.

Working Procedure 

1.The desired amount of substrate is poured into a sealed container and allowed to reach room temperature in the dark. 

2.Recommended volumes are 100 µl substrate solution per microtiter well. Development time is typically 15- 30 minutes. Optimal time is determined by the user and will vary according to the procedure and the incubation temperature. 

3.100 µl of 0.1 M NaOH is then added and mixed thoroughly. 

4.In kinetic assays, the color is read directly at 405 nm. For endpoint assays the absorbance is read at 405/620 nm.

Tips & Tricks 

• For use in hot climate countries, due to superior background characteristics, we recommend pNPP ONE (cat. no. P494181) 

• A stop solution of 0.1 M NaOH requires no hazardous labelling. In case a higher assay sensitivity is required, a 1.0 M NaOH may be used as stop solution offering an approx. increase of OD of 3%. In both cases a 1 hour stop stability is guaranteed.

Handling & Storage

• Store solution at 2-8 °C in the dark. 

• Avoid exposure to light and heat. 

• Re-dispense only into bottles made of High Density Polyethylene (HDPE), amber color. 

Dispensing guidelines are available upon request.

Specifications

Specifications & Purity

Ready-to-use (RTU)

Storage

Store at 2-8°C, Protected from light

Shipped In

Wet ice

This product requires cold chain shipping. Ground and other economy services are not available.

Images

pNPP

References

1. Zizhe Li, Liang Luo, Chaochao Chen, Qiang Li, Qiyuan Zhao, Ghulam Mujtaba Mari, Chen Xing, Xuefeng Xia, Jianzhong Shen, XueZhi Yu, Zhanhui Wang, Yantong Pan.  (2025)  Environment-friendly dual-mode immunoassay based on the inner filter effect of polydopamine-polyethylenimine copolymer nanoparticles for the highly sensitive detection of norfloxacin.  FOOD CHEMISTRY,      [PMID:40138822] [10.1016/j.foodchem.2025.143928]