PHOTOCHEMICAL DEGRADATION OF CI ACID BLACK-1

The disazo dye Naphthalene Black (C.I. Acid Black 1; C.I. 20470), which has wide application in analytical chemistry and histochemistry as well as in the coloration of wool, undergoes photochemical degradation in aqueous solution. The reaction is accelerated in the presence of hydrogen peroxide and retarded in the presence of mannitol. In addition, the reaction rate is enhanced by the incorporation of a triplet sensitizer dye. These findings are strongly suggestive that Naphthalene Black undergoes hydroxyl radical and triplet sensitized photochemical degradation. Such effects might reduce the efficacy of the dye in its applications.