Description General description o-Tolidine is a diacidic dye which is sparingly soluble in water and easily soluble in ether and alcohol. On exposure to chlorine or bromine vapors, it forms an intense blue color. This forms the basis for detection of chlorine, nitrates and hydrogen peroxide in air or water. It turns yellow on reacting with free chlorine. o-Tolidine easily forms acid salts. Application o-Tolidine has also been used to determine the presence of laccase activity in T. versicolor fungal colonies. Sensitive colorimetric reagent for gold and for free chlorine in water. Packaging 25, 100 g in glass bottle Warning May be carcinogenic.