Soxhlet extractions polychlorinated biphenyl

Automated Soxhlet extraction Polychlorinated biphenyls, organochlorine pesticides and semi-volatiles from soils, relatively dry sludges and solid wastes Allows equivalent extraction efficiency to Soxhlet extraction in 2 h... 

Sonication of polychlorinated biphenyls (PCBs) from soils has been the subject of an interlaboratory study [196] with 129 participants. Two standard methods of extraction were evaluated EPA method 3540 for Soxhlet extraction and EPA method 3550 for sonication... 

Johnson and Van Emon [57] have described a quantitative enzyme based immunoassay procedure for the determination of polychlorinated biphenyls in soils and sediments and compared the results with those obtained by a gas chromatographic method. The soil is extracted with methanol, or Soxhlet extracted or extracted with a supercritical fluid. In the case of the latter two extractants good agreement was obtained between immunoassay and gas chromatographic methods. Spiking recoveries from soil achieved ranged from 104% (Aroclor 1248) to 107% (Aroclor 1242). Detection limits were 9pg kg-1 (Aroclor 1245) and 10.5pg kg-1 (Aroclor 1242). Chlorinated anisoles, benzenes or phenols did not interfere. 

Japenga et al. [56] determined polychlorinated biphenyls and chlorinated insecticides in River Elbe estuary sediments by a procedure in which the sediments were pretreated with acetic acid, mixed with silica and Soxhlet-extracted with benzene/hexane. Humic material and elemental sulphur were removed by passing the extract through a chromatographic column containing basic alumina, on which sodium sulphite and sodium hydroxide were adsorbed. Silica fractionation was followed by gas chromatography to analyse chlorinated pesticides, polychlorinated biphenyls and polyaromatic hydrocarbons. Recovery experiments with standard solutions gave recoveries of 90-102%. 

Lopez-Avila et al. [107] showed that microwave-assisted extraction of pesticides and polycyclic aromatic hydrocarbons from soil is a viable alternative to Soxhlet extraction and needs a smaller sample volume and extraction time [108,109]. These techniques have also been compared in the case of chlorophenols. Lopez-Avila et al. compared microwave-assisted extraction with electron capture gas chromatography to ELISA for the determination of polychlorinated biphenyls in soils. Both techniques are applicable to field screening and monitoring applications. Microwave-assisted extraction [111, 112] and solid-phase microextraction [113] have been applied to the extraction of pesticides from soil. It was observed by these and other workers [114] that the selectivity of microwave-assisted extraction is highly dependent on the soil composition. 

The superiority of microwave extraction compared to traditional extraction methods for the determination of polychlorinated biphenyl compounds in indoor air samples was also shown. Again a decrease in the extraction time was highlighted the microwave procedure needed only 10 min and, followed by GC-electron capture detection, was claimed as a valuable alternative to the Soxhlet method for the extraction of six noncoplanar PCBs associated with fly ashes. 

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