GAS-CHROMATOGRAPHIC ANALYSIS AND GAS-CHROMATOGRAPHIC MASS-SPECTROMETRIC IDENTIFICATION OF COMPONENTS IN THE CYCLOHEXANE-EXTRACTABLE FRACTION FROM CONTAMINATED SEDIMENT SAMPLES

A comprehensive investigation was carried out on the cyclohexane-soluble extracts from three sediment samples. Elemental analysis of the residue after careful removal of solvent showed that nitrogen was absent, sulphur accounted for 10-20% of the residue and the carbon/chlorine ratio was high. Gas chromatography and gas chromatography-mass spectrometry confirmed that a substantial fraction of the extracts consisted of non-chlorinated long-chain alkenoic and alkanoic acids, terpenes and plant steroids and that the free organochlorine compounds were dominated by chlorinated long-chain alkanoic acids and chlorinated resin acids, whereas chloroform, chemically bound phenolic compounds, and polychlorinated biphenyls made only a small contribution. The chemical structures of constituents of the extractable organic chlorine fraction and of the corresponding methanolic alkali extracts from whole sediments were completely different; the former did not have a major contribution from products originating in chlorinated guaiacyl-C3 residues. Only ca. 8% of the organically bound chlorine could be accounted for in terms of known compounds which originated in bleachery effluents. Three hypotheses may be put forward for the nature of the unidentified components: they may not be constituents of bleachery effluents, they may not hitherto have been characterized in such effluents or they may be transformation products formed in the sediment phase. It was not possible in the light of current evidence to access which of these was correct. It was concluded that procedures used for characterization which rely heavily on gas chromatographic separation must be substantially improved to enable an acceptable level of indentification to be attained. © 1990.