Recent advances in ultratrace analysis of dioxins and related halogenated hydrocarbons

Abstract

Analytical methodology for polychlorinated dioxins and furans (PCDDs and PCDFs) in environmental samples is not standardized. Many variations exist for the extraction, cleanup, quantitation, and confirmation of these compounds and reported detection limits and recoveries vary over several orders of magnitude. This paper describes research carried out at the Canada Centre for Inland Waters over the past seven or eight years to develop reliable methodology at ultratrace levels (10−12–10−15 g/g) applicable to a wide range of environmental samples. Extraction techniques are described for biological tissue (fish, clams, leaches, eggs), fly ash, sediments, and water. Detailed cleanup procedures for the various matrices consist of most or all of the following: gel permeation chromatography liquid/liquid extraction with Na3PO4, liquid/liquid extraction with H2SO4, basic alumina chromatography, and carbon fibre chromatography. Preliminary screening of the cleaned extracts is achieved by gas chromatography equipped with a mass selective detector and positive identification by gas chromatography/mass spectrometry operated in electron impact and chemical ionization modes and with full scan and multiple ion detection. Custom software permitting the analysis of a wide range of compounds in a single run by gc/ms is reported. The presence of specific isomers of PCDDs and PCDFs is confirmed by high resolution gas chromatography/mass spectrometry. A radioimmunoassay screening procedure for PCDDs in environmental samples is also described.