Characteristics of an extraction and purification procedure for chlorinated dibenzo-p-dioxins and dibenzofurans in soil and liver

Liquid-gel partitioning using Lipidex in the determination of polychlorinated biphenyls in cod liver oil

A technique was developed for transfer of fat and polychlorinated biphenyls from cod liver oil into the lipophilic gel Lipidex 5000. Subsequent elution of the gel separated about 60% of the fat from the sample. Following further purification on aluminium oxide and silica gel, toxic non-ortho- and mono-ortho-PCB congeners were isolated in two separate fractions on charcoal. Recoveries were studied by addition of twelve different PCB congeners to 0.2 g of fat. The non-ortho-PCBs were labelled with 13C. The recoveries of 5-50 ng of the unlabelled compounds were 80-100% and those of 50-100 pg of the labelled compounds were 76-106%.

Analysis of organochlorine pesticides, polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans in human milk by extraction with the lipophilic gel Lipidex 5000

A method for multicomponent determination of organochlorine contaminants in human milk is described. The lipophilic gel Lipidex 5000 was used for extraction of lipids and organochlorine compounds. Further purification and separation was achieved by chromatography on partly deactivated aluminium oxide, Lipidex, silica gel and active basic and acidic aluminium oxide. The concentrations of pesticides and polychlorinated biphenyls (PCBs) were determined by electron-capture gas chromatography. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined by selected-ion monitoring capillary column gas chromatography-mass spectrometry at a resolution of 8000-9000. The levels of 2,2-bis(4-chlorophenyl)-1,1,1-trichloroethane, 1,1-bis(4-chlorophenyl)-2,2-dichloroethene, hexachlorobenzene, alpha-hexachlorocyclohexane, beta-hexachlorocyclohexane, dieldrin, trans-nonachlor, oxychlordane and PCBs found by this method agreed with the levels determined using a previous solvent-extraction method. Recovery experiments were performed by addition of pentachlorophenol and certain PCDDs and PCDFs. The average recovery of 0.5-2.0 ng pentachlorophenol per ml milk was 92%. Ten PCDDs and PCDFs reported to occur in milk were added at levels between 0.5 and 50 pg per ml milk. Recoveries of these compounds were on an average 79-91%.

A persistent hexabromonaphthalene isomer is 2,3,4,5,6,7-hexabromonaphthalene

Polybrominated biphenyl (PBB) mixtures are contaminated with brominated naphthalenes formed during the synthesis procedure. Synthesis of hexabromonaphthalenes (HBNs) by direct bromination of naphthalene results in a mixture of two isomers. The identity of the major isomer, 1,2,3,4,6,7-HBN, was previously confirmed (Birnbaum et al., 1983). The minor isomer is definitively identified as 2,3,4,5,6,7-HBN by high-field nuclear magnetic resonance (NMR) spectroscopic analysis of brominated [1-13C]naphthalene-derived products. This isomer is extremely persistent and can be isolated from the liver of rats 10 d after treatment with the HBN mixture by a combination of solvent extraction and partition and adsorption chromatography.