Detection and identification of trace amounts of organochlorine substances by gas chromatography-high-resolution mass spectrometry

Abstract

A search and identification of organochlorine compounds in soils with abnormally high level of octachlorodibenzo-p-dioxin from the northern province of Vietnam were carried out by gas chromatography-high-resolution mass spectrometry using a magnetic sector mass spectrometer in the scan and multi-ion detection modes at resolution 8000–10000. An algorithm for determining the exact mass, molecular formula, and molecular structure of organochlorine substances at ultratrace concentrations was proposed. Twenty-eight organohalogen compounds were found, 22 of which were derivatives of polychlorinated dibenzo-p-dioxins and polychlorinated diphenyl ethers with from one to three methoxy groups; the concentration range for these compounds is 0.0001–0.5% relative to the level of octachlorodibenzo-p-dioxin (OCDD). The existence of such substances was assumed, as they may be metabolites of polychlorinated dibenzo-p-dioxins (PCDD) or other chlorinated aromatic compounds, but most of these compounds have never been described in the literature. Some of the compounds could be considered as possible biotransformation products of OCDD; the others of different origin and may be byproducts of the formation of OCDD in nature.