Analytical methodology of the Dow Chemical Company for the determination of selected chlorinated dibenzo-p-dioxins and dibenzofurans in stack gas effluent matrices: Part II: Isomer method for determination of tetra- through octa-chlorinated congener group “2378”-substituted isomer concentrations

Abstract

This procedure is a modification of the analytical method presented in Part I. It permits the determination of “2378”-substituted CDD and CDF isomers (chlorinated dibenzo-p-dioxins and dibenzofurans), over the range of congener groups having from four to eight chlorine substituents, in stack gas effluent samples containing both gaseous and particulate emissions. Stack gas samples are collected isokinetically from an operating process vent to the atmosphere using a United States Environmental Protection Agency (US EPA) modified Method 5 sample collection train. Analytes are recovered by subjecting the entire contents of a sampling train to extraction with benzene so as to produce a total-sample-crude-extract. An aliquot of the crude extract is fortified with [ 13C 12]-labeled CDD/CDF isomer internal standards and subjected to a 2-dimensional HPLC (high performance liquid chromatography) cleanup procedure that is designed to isolate the seven “2378”-CDD and ten “2378”-CDF isomers into separate fractions from a single analysis aliquot. Final HRGC-LRMS (high resolution gas chromatography - low resolution mass spectrometry) examination of these fractions provides the necessary qualitative and quantitative data for each analyte.