CAS 91-94-1: 3,3′-Dichlorobenzidine

3,3'-Dichlorobenzidine (3,3'-DCB) is a carcinogen that is used in the analytical method of determining fatty acids. 3,3'-DCB reacts with amines to form a diazonium salt, which can be detected by a reaction solution. The reactivity of 3,3'-DCB depends on the concentration of potassium dichromate and amines present. Monoclonal antibodies are used to detect the presence of benzidine in urine samples at concentrations as low as 0.1 mg/L. Rat liver microsomes are commonly used for this detection method because they have high levels of cytochrome P450 enzymes that catalyze the formation of benzidine from 3,3'-DCB. Chemical inhibitors such as hydrochloric acid can be added to stop this process and prevent false-positive results. Bladder cancer has been shown to be associated with occupational exposure to 3,3'-DCB.