Reversed-phase liquid chromatography of the twenty-two tetrachlorodibenzo-p-dioxin isomers on pyrenylethyl- and octadecylsilylated silica gel columns

To purify the tetrachlorobenzo-p-dioxins synthesized for chemical and biological reference standards, reversed-phase liquid chromatography on pyrenylethyl- and octadecylsilylated stationary phase (PYE and C₁₈) columns was employed with 100% methanol. The pyrenylethyl phase satisfactorily separated isomers resulting from mixtures of reaction products which had not been adequately separated with conventional C₁₈ or silica gel. The use of a single chromatographic mode, liquid chromatography, and a single mobile phase with columns of distinctly different properties, C₁₈ and PYE, separates 20 of the 22 isomers from each other and from the 1246/1249 pair. (The observed properties of the two columns afford insight into steric and polarizability differences among isomers.