PNPP Stop Solution

Store at room temperature (25ºC). Refrigerated temperatures will not harm the reagent.

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Stop Solution for pNPP is a proprietary dry-blend stop solution for use with AP substrates, such as pNPP and is compatible with our pNPP-based alkaline phosphatase substrate pNPP 1-Component AP Microwell Substrate. This product is suitable for all endpoint ELISAs using an AP substrate for color development of an AP-conjugate.

pNPP substrates react with alkaline phosphatase yielding a soluble yellow reaction product. Stop Solution for AP Substrates stabilizes the reaction for one hour and does not change the color or the absorbance of the yellow chromogen. The absorbance is read at 405 nm to 420 nm. Larger volumes are available upon request.

1. Reconstitute by adding 100mL of distilled or deionized water. Allow approximately 5 minutes to dissolve.
2. After reconstitution, allow product to equilibrate to room temperature (25°C) prior to use.
3. Add stop solution to plate well. Equal volumes of stop solution and AP microwell substrate should be used. We recommend using 100 µL of pNPP substrate and 100 µL of this stop solution per well. The stopped reaction is stable for 1 hour.
4. Read absorbance at 405-420 nm within 60 minutes. For best results, sample absorbance should be monitored and stopped before values exceed 2.5 OD units.
5. Analyze data.