Tetrachloroazobenzene in 3,4-dichloroaniline and its herbicidal derivatives: propanil, diuron, linuron, and neburon.

The presence of 3,3', 4,4'-tetrachloroazobenzene (TCAB) was determined by high performance liquid chromatography in 3, 4-dichloroaniline and herbicides made therefrom. The concentrations of TCAB in 3, 4-dichloroanilines and in different herbicides from a variety of manufacturers ranged from 9 to 1400 micrograms/g (ppm). The chloracnegenic potential of these products, as determined by rabbit ear test, suggests that it is in the same range of 2, 3, 7, 8-tetrachlorodibenzodioxin, a known potent chloracnegenic agent.