Description_x000D_ Application_x000D_ Developed for use as a soluble substrate for the detection of alkaline phosphatase activity in Enzyme Immunoassays (EIA). pNPP is the substrate of choice in high sensitivity alkaline phosphatase-based EIA assays.One pNPP tablet and one Tris buffer tablet are dissolved in deionized water and provide a ready-to-use substrate. Each Sigma FAST pNPP tablet set yields a solution containing 1.0 mg/ml pNPP, 0.2 M Tris buffer. EIA applications using pNPP may be read in timed assays or stopped with 3N NaOH for delayed readings. SIGMAFAST™ require only the addition of distilled or deionized water to prepare an active substrate solution. Tablets are individually packaged in foil packets._x000D_ Reconstitution_x000D_ Each tablet set dissolved in 20 mL deionized water yields a ready-to-use buffered solution containing pNPP._x000D_ Legal Information_x000D_ SIGMAFAST is a trademark of Sigma-Aldrich Co. LLC