Isomer-specific determination of hexachlorodibenzo-p-dioxins by oxygen negative chemical ionization mass spectrometry, gas chromatography, and high-pressure liquid chromatography

All ten hexachlorodibenzo-p-dioxin (HCDD) isomers, prepared by micropyrolysis of chlorophenates, were studied by using mass spectrometry, gas chromatography, and high-pressure liquid chromatography. Of several ionization modes studied, oxygen negative chemical ionization was the most suitable for isomer identification. This technique enabling isomer specific identification to be carried out was applied to hexachlorodioxin impurities in pentachlorophenol samples and detected small amounts of 4:2 substituted isomer not previously known. 17 references, 7 figures, 2 tables.