Description Application 3,3′-Diaminobenzidine has been used as a chromogen for the visualization in immunohistochemistry of chondrosarcoma sections, mammary carcinomas and brain tissue sections. Peroxidase substrate; reagent for spectrophotometric determination of selenium. Packaging 1, 5 g in glass bottle 10, 25 g in poly bottle Biochem/physiol Actions DAB (3,3′-Diaminobenzidine) is utilized in many applications for the visualization of peroxidase activity. In the peroxidase reaction, DAB serves as a hydrogen donor in the presence of peroxide. The oxidized DAB forms an insoluble brown end-product for use in the immunohistological and immunoblotting staining procedures.