Application The DAB (3,3′-Diaminobenzidine tetrahydrochloride) Two-component Enhanced Liquid Substrate System is a precipitating substrate system for peroxidase. DAB Two-component Liquid Substrate System produces a brown precipitate for use in immunohistological and immunoblotting staining procedures. Caution Stable for up to 18 mo. when stored at 2-8 °C in the original container. Quantity Each DAB Two-component Liquid Substrate System will provide 100 mL of the DAB substrate solution.