Extraction polychlorinated biphenyl from

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... 

Hawthorne et al. [53] studied the effect of temperature and pressure on supercritical fluid extraction efficiencies of polychlorinated biphenyls in river sediments. At a temperature of 50°C, raising the pressure from 350 to 650atm, had a beneficial effect on recovery of polychlorinated biphenyls from sediments. Recovery was improved however as the extraction temperature was increased from 50-200°C. 

The Extraksol process can extract organic contaminants such as oils and greases, polynuclear aromatic hydrocarbons (PAHs), pentachlorophenols (PCPs), and phenols from a variety of solid matrices. The Extraksol process can extract polychlorinated biphenyls (PCBs) from clay-bearing soil, sand, and FuUer s earth. Extraksol has successfully treated various media such as activated carbons, refinery sludges, and wood treatment sludges. 

The Soilex process is an ex situ process for extracting polychlorinated biphenyls (PCBs) from soil, sediments or sludge. The soil is mixed with water and an organic solvent to dissolve and remove the PCBs. 

Yang, Y., Bowadt, S., Hawthorne, S.B., Miller, D.J. Subcritical water extraction of polychlorinated biphenyls from soil and sediment. Anal. Chem. 67, 4571 576 (1995)... 

Column chromatography of the lipid or non-saponlflable lipid extracts on alumina over silica gel columns, or silica gel columns, to partially Isolate polychlorinated biphenyls from other classes of compounds used procedures described previously (10, 29). 

Mills AG, Jefferies TM. 1993. Rapid isolation of polychlorinated biphenyls from milk by a combination of supercritical-fluid extraction and supercritical-fluid chromatography. J Chromatogr 643(l-2) 409-418. 

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... 

Supercritical fluid extraction Polychlorinated biphenyls and organochlorine pesticides from soils, sediments, fly ash, solid-phase extraction media, and other solid materials which are amenable to extraction with conventional solvents As method 3560... 

Monocrotaline, a pyrrolizidine alkaloid of chemotherapeutic interest, has been extracted from the seeds of Crotalaria spectabilis using supercritical carbon dioxide and carbon dioxide-ethanol mixtures (29). Other alkaloids that have been extracted using SFE include nicotine and caffeine. Environmental applications of supercritical fluids include regeneration of activated carbon, extraction of organic contaminants like polynuclear aromatic hydrocarbons and polychlorinated biphenyls from water and soils, and the newly emerging field of supercritical water oxidation. 

The extraction of polyaromatic hydrocarbons from soil and urban particulates by superheated water was reported in 1994 [17]. Extraction of compounds up to ben-zo[a]pyrene was virtually complete in 15 min at 250°C, with a flow rate of 1 ml mim and a sample of 0.5 g. Good but less complete results were obtained when extracting urban air particulates. The pressure did not influence the extraction behavior, provided it was sufficient to maintain water as a Hquid. The extraction of polychlorinated biphenyls from soil and a river sediment was also found to be complete in 15 min at 250°C [18]. Work with a wider range of compounds showed that extraction was class selective [6, 19], with phenols and Hghter aromatics being extracted at 50 to 150°C, polyaromatic hydrocarbons and lighter ahphatics at 250 to 300°C, but the heavier ahphatics only removed by steam at 250 to 300°C. This selectivity has been compared to other extraction methods [20]. The extraction of agrochemicals from soil has also been studied [6]. 

Solvent extraction is based on preferential solubility of an analyte in one of two immiscible phases. There are two common situations that are encountered in analysis extraction of an organic analyte from a solid phase, such as soil, into an organic solvent for subsequent analysis, and extraction of an analyte from one liquid phase into a second immiscible liquid phase, such as extraction of polychlorinated biphenyls from water into an organic solvent for subsequent analysis. 

V. Leoni, G. Puecetti, R. J. Colombo, and A. M. D Ovidio, The use of Tenax for the extraction of pesticides and polychlorinated biphenyls from water. II. Tests with artificially polluted and natural waters,/. Chromatogr. 125, 399-407 (1976). 

Ramos, J.J., Dietz, C., Gonzalez, M.J., and Ramosa, L. (2007) Miniaturised selective pressurised liquid extraction of polychlorinated biphenyls from foodstuffs. /. Chromatogr. A, 1152, 254-261. 

Extraction, employs a liquid solvent to remove certain compounds from another liquid using the preferential solubility of these solutes in the MSA. For instance, wash oils can be used to remove phenols mid polychlorinated biphenyls (PCBs) from die aqueous wastes of synthetic-fuel plants and chlorinated hydrocarbons from organic wastewater. 

The most critical decision to be made is the choice of the best solvent to facilitate extraction of the drug residue while minimizing interference. A review of available solubility, logP, and pK /pKb data for the marker residue can become an important first step in the selection of the best extraction solvents to try. A selected list of solvents from the literature methods include individual solvents (n-hexane, " dichloromethane, ethyl acetate, acetone, acetonitrile, methanol, and water ) mixtures of solvents (dichloromethane-methanol-acetic acid, isooctane-ethyl acetate, methanol-water, and acetonitrile-water ), and aqueous buffer solutions (phosphate and sodium sulfate ). Hexane is a very nonpolar solvent and could be chosen as an extraction solvent if the analyte is also very nonpolar. For example, Serrano et al used n-hexane to extract the very nonpolar polychlorinated biphenyls (PCBs) from fat, liver, and kidney of whale. One advantage of using n-hexane as an extraction solvent for fat tissue is that the fat itself will be completely dissolved, but this will necessitate an additional cleanup step to remove the substantial fat matrix. The choice of chlorinated hydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride should be avoided owing to safety and environmental concerns with these solvents. Diethyl ether and ethyl acetate are other relatively nonpolar solvents that are appropriate for extraction of nonpolar analytes. Diethyl ether or ethyl acetate may also be combined with hexane (or other hydrocarbon solvent) to create an extraction solvent that has a polarity intermediate between the two solvents. For example, Gerhardt et a/. used a combination of isooctane and ethyl acetate for the extraction of several ionophores from various animal tissues. 

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... 

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... 

Aparicio I, Santos JL, Alonso E (2007) Simultaneous sonication-assisted extraction, and determination by gas chromatography-mass spectrometry, of di-(2-ethylhexyl)phthalate, nonylphenol, nonylphenol ethoxylates and polychlorinated biphenyls in sludge from waste-water treatment plants. Anal Chim Acta 584 455 161... 

Picer and Picer [357] evaluated the application ofXAD-2, XAD-4, and Tenax macroreticular resins for concentrations of chlorinated insecticides and polychlorinated biphenyls in seawater prior to analysis by electron capture gas chromatography. The solvents that were used eluted not only the chlorinated hydrocarbons of interest but also other electron capture sensitive materials, so that eluates had to be purified. The eluates from the Tenax column were combined and the non-polar phase was separated from the polar phase in a glass separating funnel. Then the polar phase was extracted twice with n-pentane. The -pentane extract was dried over anhydrous sodium sulfate, concentrated to 1 ml and cleaned on an alumina column using a modification of the method described by Holden and Marsden. The eluates were placed on a silica gel column for the separation of PCBs from DDT, its metabolites, and dieldrin using a procedure described by Snyder and Reinert [359] and Picer and Abel [360]. 

An emulsion of the oil and propylene carbonate (imiscible with the oils) is pumped through the cell with a carbon-felt cathode. The polychlorinated biphenyls are continously extracted into the electrolysis medium. 30-50% current efficiencies for the decrease in the polychlorinated biphenyl concentrations from 700 to less than 1 ppm are possible. 

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]. 

Accelerated solvent extraction is a new technique for the extraction of a range of organic pollutants from soils and related material. The technique is based on the use of a solvent or combination of solvents to extract organic pollutants at elevated pressure and temperature from a solid matrix. The range of organic pollutants for which the technique is proposed includes semivolatile compounds, organochlorine pesticides, organophosphorus pesticides, chlorinated herbicides, polychlorinated biphenyls and polycyclic aromatic hydrocarbons [53-56],... 

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. 

Zajicek, J.L. Tillitt, D.E. Huckins, J.N. Petty, J.D. Potts, M.E. Nardone, D.A. 1996, Application of Enzyme-Linked Immunosorbent Assay (ELISA) for Measurement of Polychlorinated Biphenyls (PCBs) from Hydrophobic Solutions Extracts of Fish and Dialysates of Semipermeable Membrane Devices (SPMDs). In Environmental Immunochemical Methods, ACS Symposium Series 646 American Chemical Society Washington, D.C. Chapter 26, pp 307-325. 

TechXtract is an extraction technology that has been used to remove a variety of contaminants from the surfaces of concrete, steel, brick, and other materials. Target contaminant types include organics, heavy metals, radionuclides, and polychlorinated biphenyls (PCBs). The technology uses proprietary chemical formulations in successive steps to remove these contaminants. The process employs as many as 25 different components in 3 separate chemical formulations that are applied to the contaminated surface and then removed in a multi-step, multicycle sequence. TechXtract is commercially available and has been used at multiple sites. 

The Microwave-Assisted Process (MAP ) technology uses microwaves, and solvents that are relatively transparent to microwaves, to extract chemicals from various matrices based on the temperature differential between the solvent and the target compound. According to the developers, the technology is applicable to soils and wastes containing polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), total petroleum hydrocarbons (TPH), and other organic compounds. 

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