Stop Solution for AP Substrates (STOPP) is a dry powder for use with pNPP-based colorimetric substrates. To use, reconstitute with DiH2O. STOPP 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.
- Reconstitute STOPP by adding 100 mL DiH2O and mix well.
- 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 (SUBP) and 100 µL of STOPP per well. The stopped reaction is stable for 1 hour.
- 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.