ImmunoTek Plus™ Chemiluminescent Peroxidase Substrate, Membrane/Blotting (Luminol)Stabilized Luminol based substrates can detect horseradish peroxidase at the femtogram level. Chemiluminescent substrates provide superior sensitivity compared to competitor products. The substrate is supplied as two components. Components:HRP-AHRP-BStorage and Stability:Store components at 4°C. Stable for 6 months after receipt. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.