Polychlorinated biphenyls sampling

SW-846, is used to measure emissions of semivolatile principal organic constituents. Method 0010 is designed to determine destruction and removal efficiency (DRE) of POHCs from incineration systems. The method involves a modification of the EPA Method 5 sampling train and may be used to determine particulate emission rates from stationary sources. The method is applied to semivolatile compounds, including polychlorinated biphenyls (PCBs), chlorinated dibenzodioxins and dibenzofurans, polycyclic organic matter, and other semivolatile organic compounds. 

In general, capillary gas chromatography provides enough resolution for most determinations in environmental analysis. Multidimensional gas chromatography has been applied to environmental analysis mainly to solve separation problems for complex groups of compounds. Important applications of GC-GC can therefore be found in the analysis of organic micropollutants, where compounds such as polychlorinated dibenzodioxins (PCDDs) (10), polychlorinated dibenzofurans (PCDFs) (10) and polychlorinated biphenyls (PCBs) (11-15), on account of their similar properties, present serious separation problems. MDGC has also been used to analyse other pollutants in environmental samples (10, 16, 17). 

A. Glausch, G. P. Blanch and V. Schurig, Enantioselective analysis of chkal polychlorinated biphenyls in sediment samples by multidimensional gas cliromatography-elec-ti on-capture detection after steam distillation-solvent exti action and sulfur removal , J. Chromatogr. 723 399-404 (1996). 

E. A. Hogendoom, G. R. van der Hoff and P. van Zoonen, Automated sample clean-up and fractionation of organochlorine pesticides and polychlorinated biphenyls in human milk using NP-HPEC with column-switching , J. High Resolut. Chromatogr. 12 784-789 (1989). 

SFE is used mainly for nonpolar compounds [e.g. polychlorinated biphenyls (PCBs)]. Typically, small aliquots of soil (0.5-10 g) are used for extraction. The extraction solvent is a supercritical fluid, most commonly carbon dioxide, which has properties of both a liquid and gas. The supercritical fluid easily penetrates the small pores of soil and dissolves a variety of nonpolar compounds. Supercritical carbon dioxide extracts compounds from environmental samples at elevated temperature (100-200 °C) and pressure (5000-10 000 psi). High-quality carbon dioxide is required to minimize... 

Figure 8.9 is an example of the use of solvent extraction to isolate polychlorinated biphenyls from a fat sample [6]. In this example the matrix is chemically modified to improve the selectivity of the extraction. The fat is first hydrolyzed by refluxing in 1 N ethanolic potassium hydroi prior to the... 

Figure 8.9 Solvent partition schene for the isolation of polychlorinated biphenyls from fat samples.

An important application of carbon-skeleton gas chromatography is the simplification of the analysis of complex samples such as polychlorinated biphenyls, polybrominated biphenyls and polychloroalkanes [709-711], These complex mixtures of halogenated isomers produce multiple peaks when separated by gas chromatography, making quantitation difficult. The isomers have identical carbon skeletons, resulting in a very simple chromatogram after hydrodechlorination. 

Table 1 Concentrations of chlorinated polycyclic aromatic hydrocarbons (CIPAHs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in ambient air, soil, and human samples collected from e-waste recycling and reference sites in China... 

Bordajandi, L.R., Korytar, P., De Boer, J., Gonzalez, M.J. (2005). Enantiomeric separation of chiral polychlorinated biphenyls on P-cyclodextrin capillary columns by means of heart-cut multidimensional gas chromatography and comprehensive two-dimensional gas chromatography applications to food samples. J. Sep. Sci. 28, 163-171. 

The important influence that sample container materials can have on seawater sample composition is illustrated next by two examples one concerning the storage of metal solutions in glass and plastic bottles, the other concerning the storage of solutions of phthalic acid esters and polychlorinated biphenyls in glass and plastic. 

Losses of Phthalic Acid Esters and Polychlorinated Biphenyls from Seawater Samples During Storage... 

Colenut and Thorburn [51,52] have also described the procedure using gas stripping of the aqueous sample followed by adsorption onto active carbon from which surface they are taken up in an organic solvent for gas chromatographic analysis. They optimized conditions for the determination of parts per billion of pesticides and polychlorinated biphenyls. 

The ubiquity of PCBs is indicated by their presence in environmental samples from the polar regions of air, snow, ice, water, and in living organisms (Norstrom et al. 1988 Hargrave et al. 1989 Larsson et al. 1992 Tanabe et al. 1993). The presence of PCBs in such remote areas suggests the importance of atmospheric transport. The Committee on the Assessment of Polychlorinated Biphenyls... 

Asplund, L., A.-K. Grafstrom, P. Haglund, B. Jansson, U. Jamberg, D. Mace, M. Strandell, and C. de Wit. 1990. Analysis of non-ortho polychlorinated biphenyls and polychlorinated naphthalenes in Swedish dioxin survey samples. Chemosphere 20 1481-1488. 

Buser, H-R. and M.D. Muller. 1986. Methythio metabolites of polychlorinated biphenyls identified in sediment samples from two lakes in Switzerland. Environ. Sci. Technol. 20 730-735. 

Porte, C., D. Barcelo, and J. Albaiges. 1988. Quantitation of total versus selected polychlorinated biphenyl congeners in marine biota samples. Jour. Chromatogr. 442 386-393. 

Schwartz, T.R., D.E. Tillitt, K.R Feltz, and RH. Peterman. 1993. Determination of mono- and non-0,0 -chlorine substituted polychlorinated biphenyls in Aroclors and environmental samples. Chemosphere 26 1443-1460. 

Two-dimensional GC can be used to separate complex mixtures of polyaromatic compounds, and MS used to subsequently identify the compounds. In this method, the original sample is injected into a gas chromatograph with one type of column. As the components exit the first GC, they are fed into a second GC, with a different column, for further separation and finally into a mass spectrometer. In this way, compounds that coeluted from the first column are separated on the second. Focant et al. [19] were able to separate polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF), and coplanar polychlorinated biphenyl (cPCB) using this type of analytical procedure, including isotope dilution TOF-MS. These compounds are frequently found as contaminants in soils surrounding industrial settings thus, the ability to separate and identify them is extremely important [6,12,19],... 

One advance in the area of LLE is the use of solid supports that facilitate the partitioning of the analyte(s) of interest. LLE extraction methods involving nonpolar matrices often suffer from the formation of emulsions, and using the solid support is a possible solution. In one study, polychlorinated biphenyls, dioxins, and furans were extracted from the lipid fraction of human blood plasma [32], using diatomaceous earth as the solid support. Long glass columns (30 cm) were packed with several layers of Chem-Elut (a Varian product) and sodium chloride. The plasma samples were diluted with water and ethanol and passed over the columns. A mixture of isopropanol and hexane (2 3) was passed over the column and the LLE was performed. It can be concluded that the LLE with the solid support is easier to perform and can be applied to other lipid heavy matrices such as milk [32]. 

Goerlitz and Law [59] determined chlorinated insecticides in sediment and bottom material samples, which also contained polychlorobiphenyls by extracting the sample with acetone and hexane. The combined extracts were passed down an alumina column. The first fraction (containing most of the insecticides and some polychlorinated biphenyls and polychlorinated naphthalenes) was eluted with hexane and treated with mercury to precipitate sulphur. If the polychlorinated hydrocarbons interfered with the subsequent gas chromatographic analysis, further purification on a silica gel column was necessary. 

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