Although chlorine bleach is commonly employed in many laboratories as a neutralization procedure, it is not effective in removing the mutagenic properties of DAB. A potassium permanganate-sulfuric acid procedure is, however, an effective way of neutralizing this toxic compound.

1. Take up bulk quantities of diaminobenzidine tetrahydrochloride dehydrate in water and bulk quantities of the free base in 0.1 M hydrochloric acid so that the concentration of DAB does not exceed 0.9 mg/ml. Dilute solutions with the same buffer, if necessary, so that the concentration does not exceed 0.9 mg/ml.
2. For each 10 ml of solution, add 5 ml of 0.2 M potassium permanganate solution and 5 ml of 2 M sulfuric acid solution.
3. Allow the mixture to stand overnight, decolorize by the addition of sodium ascorbate, neutralize and dispose solution down the drain with copious amounts of water.