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 (31.6 g KMnO4 per liter of solution with water) and 5 ml of 2 M sulfuric acid solution (112 ml concentrated H2S04 per liter of solution with water).
3. Allow the mixture to stand for at least 10 hours.
4. Test to ensure pH of solution is between 6-9. Dispose solution down the drain with copious amounts of water.