D 1350 (OTTO) 3,3-Diaminobenzidine, GR 99% Cas 91-95-2 - used as peroxidase substrate and a reagent for spectrophotometric determination of selenium. D 1350 (OTTO) 3,3-Diaminobenzidine, GR 99% Cas 91-95-2 - used for immunohistochemical staining of nucleic acids and proteins.