Determination of chlorinated dibenzo-p-dioxins and dibenzofurans in various materials.

The determination of specific chlorinated dibenzo-p-dioxins is complicated by the large number of structurally similar compounds which are normally present in many samples as well as the usual problems of removal of the matrix itself. Thus separation techniques with the highest resolving power and detectors with the most specific response must be used. The certainty of the results must be established so that proper action can be taken to prevent exposure by plant personnel and to assure that these materials are not spread in the environment. In order properly to assess the wide range of biological activity which these compounds exhibit, the final determination must be specific, sensitive, and reliable. The search for such a method began at Dow Chemical Company in 1964 when the caustic insoluble residue from 2,4,5-trichlorophenol distillation residue was examined by thin-layer chromatography and the most biologically active spot identified as 2,3,7,8tetrachlorodibenzo-p-dioxin by comparison with synthesized material (N. E. Skelly, Dow Chemical Company, personal communication, 1964). The isolated and synthesized materials were compared and examined by mass spectrometry, infrared spectrometry,