Preparation of qualitative standard mixtures of polychlorinated dibenzo-rho-dioxins and dibenzofurans by ultraviolet and psi-irradiation of the octachloro compounds.

High-resolution gas chromatography using an OV-17 glass capillary column and mass spectrometry were used to analyze uv-and psi-irradiated octachlorodibenzo-rho-dioxin and octachlorodibenzofuran. Under the conditions investigated, dechlorination of these compounds to lower chlorinated dibenzo-rho-dioxins and dibenzofurans appears to be the major reaction pathway. The resulting mixtures of penta-, hexa-and heptachloro compounds can be used as easily and safely prepared qualitative reference samples to determine gas chromatographic, mass spectrometric and other properties of individual components for which pure standards are not available.