Volume 24, Issue 4 (October 1979)
Increased Safety and Specificity in the Thin-Layer Chromatographic Identification of Marihuana
An in-depth study of alleged false positives in the chemical identification of marihuana has previously been reported . Subsequent to publication of that paper, two health and safety considerations have come to our attention. Fast Blue B (3,3′-dimethoxybiphenyl 4,4′-bisdiazonium chloride) is suspected of being carcinogenic  because of the presence of unreacted amines, which are known carcinogens . More importantly, benzene, which is the major component in the thin-layer chromatographic (TLC) system , has now been conclusively established as a carcinogen. The Occupational Safety and Health Administration (OSHA) has issued an emergency temporary standard because a grave danger exists for workers exposed to benzene. Because of the danger and stringent regulations  it was decided to discontinue the use of benzene.