Study of chlorinated diphenyl ethers and chlorinated 2-phenoxyphenols as interferences in the determination of chlorinated dibenzo-p-dioxins and chlorinated dibenzo furans in biological samples.

Two classes of environmentally occurring chlorinated aromatic hydrocarbons which have mass spectral properties similar to the chlorinated dibenzo-p-dioxins (dioxins) and chlorinated dibenzofurans (furans) were studied. Standards of chlorinated diphenyl ethers (CDEs), and chlorinated 2-phenoxyphenols (CPPs) and their methyl ethers, along with the dioxins and furans were passed in steps through a simple method for the analysis of the latter compounds in biological samples. The CDEs, which interfere with the determination of furans by mass spectrometry, had similar extraction, high-performance liquid chromatographic and gas chromatographic properties as the furans but, in all cases studied, were well separated from them on an activated Florisil column using combinations of hexane and dichloromethane as eluting solvents. The higher CPPs on the other hand tended to generate dioxin residues by ring closure when exposed to strong hydrochloric acid solution during sample preparation. In addition, their methyl ethers containing four to six chlorines tracked completely through all stages of the method with the dioxins. Thus, if the methyl ethers of CPPs were present in a sample extract, additional mass spectral information would be needed to further differentiate them from dioxins in environmental samples.