pNPP Substrate, 120 mL

A ready-to-use chromogenic substrate solution prepared in a diethanolamine buffer at working strength for alkaline phosphatase-based immunoassays, dispensed directly into microplate wells without reconstitution or pH adjustment. The para-nitrophenyl phosphate is hydrolyzed by alkaline phosphatase tethered to detection antibodies, releasing a yellow, water-soluble product measured at 405 nm on a standard absorbance plate reader. STEMCELL Technologies formulates this reagent to integrate with antibody pair ELISA workflows used to quantify human and mouse cytokines, immunoglobulins, and other secreted proteins in hybridoma screening and B cell characterization studies conducted for research use only.

Each 120 mL bottle supplies sufficient reagent for several full-plate developments when used at typical dispensing volumes of 100 to 200 µL per well. Reactions can be terminated with a 3 M sodium hydroxide stop solution when a fixed endpoint is needed for batch reads on a microplate reader. Store refrigerated and protect from light; the buffered liquid stays free of precipitate, preserves activity across multiple experimental runs, and remains stable through the labelled expiry date on the bottle. The non-fluorescent chemistry supports routine antibody titering, supernatant analysis, and cell culture supernatant profiling without specialized detection instrumentation, simplifying bench workflows for everyday immunoassay work.