Organic pollutants extraction procedures

Recent publications indicate the cloud-point extraction by phases of nonionic surfactant as an effective procedure for preconcentrating and separation of metal ions, organic pollutants and biologically active compounds. The effectiveness of the cloud-point extraction is due to its high selectivity and the possibility to obtain high coefficients of absolute preconcentrating while analyzing small volumes of the sample. Besides, the cloud-point extraction with non-ionic surfactants insures the low-cost, simple and accurate analytic procedures. 

Immunoaffinity procedures can be performed either on-line or off-line, and can be coupled to chromatographic systems [ 118,119] or even to immunoassays [120]. Many examples can be found in the literature regarding the use of immunoaffinity extraction of drugs and pharmaceuticals from biological matrices, as well as of organic pollutants such as pesticides from environmental samples [115,121-124]. 

Keith et al. [36] and Reijnders et al. [37] reviewed applications of gas chromatography-mass spectrometry to sediment analysis. Lopez-Avila et al. [38] investigated the efficiency of dichloromethane extraction procedures for the isolation of organic compounds from sediments prior to gas chromatography-mass spectrometry. The compounds investigated were the 51 priority pollutants listed by the Environmental Protection Agency, USA. 

Gas chromatography (GC) is the most common analytical technique for the quantitative determination of organic pollutants in aqueous and nonaqueous samples. In environmental analysis, a very low detection limit is required to determine the pollutants at trace levels. Such low detection can be achieved by sample concentration followed by cleanup of the extract to remove interfering substances. Sample extractions and cleanup procedures are described in detail in Chapter 5 of Part 1 of this text. 

This is applied to separate acidic or basic organics from neutral organics. The solvent extract is shaken with water that is highly basic. The acidic organics partition into the aqueous layer whereas, the basic and neutral compounds stay in the organic solvent and separate out. After this, the aqueous layer is acidified to a pH below 2, and then extracted with methylene chloride. The organic layer now contains the acid fraction Phenols, chlorophenoxy acid, herbicides, and semivolatile organic pollutants are cleaned up by the procedure described above. 

Adsorbents, extraction procedures, organic pollutants, 113 Aerosol, problems in measuring, coal combustion, 312-317 Aerosol carbon data, results and discussion, carbon isotope tracers, 270-275... 

As a benefit the product of the electrooxidation process is C02 and can be used, after separation of excess C02 and other gaseous reaction products, for the extraction procedure. A pressure cell has been constructed, where the C02 loaded with the organics is contacted with the electrolyte containing the oxidation agent, so that the pollutants can be destroyed by oxidation. Figure 5 shows the piping and instrumentation diagram of this apparatus. 

Extraction procedures for persistent organic pollutants like PCB and DDT residues can be applied with success for Chloralkylene components. Hexane-acetone or similar solvent mixtures are adequate [62]. Sulfuric acid treatment in cleanup leaves the isopropyl-PCBs unaffected. However, oxidation, e.g., with chromic acid degrades the alkyl-PCBs [62]. 

Supercritical Fluids (SFs) allow analytes to be extracted from solid samples, i.e., marine sediments, faster and more efficiently since they have lower viscosity and higher diffusivity than liquid solvents (56). CO2 is the most widely used supercritical fluid with or without a modifier, e.g. methanol and toluene. A very exhaustive discussion on the role of a modifier in the enhancement of the extraction efficiency was recently published (39). Few procedures have been described in the literature based on SFE of organic pollutants from environmental samples, including PCBs and PAHs (39, 41, 56-59). Generally, the extraction is performed... 

Fast and Selective Analytical Procedures for Determination of Persistent Organic Pollutants in Food and Feed Using Recent Extraction... 

Abstract. In this study honey collected from local markets or made by private peasants from eighteen regions of Romania during years 2002-2004 were analyzed for organochlorine pesticides (OCPs). An analytical procedure based on liquid-liquid extraction with n-hexane followed by gas chromatography with electron capture detection (GC-ECD) has been developed. For clean-up and preconcentration purposes was used a usual sorbent material (florisil). Limits of detection were from 0.02 and 0.05 pg /Kg. The pesticide endrin was the most frequently detected in 61% of the samples, followed by dieldrin in 16% of the samples. DDT and their metabolites were detected in 11% of the samples. Results indicate that honey consumers should not be concerned about the amounts of organic pollutants found in Romanian honey. 

Fortifying laboratory water samples approaches actually recovering field samples if a pesticide is completely dissolved and not associated with suspended matter and the other water quality characteristics are similar to natural water (pH, T, ionic strength). In another approach natural water characteristics are altered to laboratory fortification specification to obtain maximum efficiency and to be able to standardize extraction procedures. DiflEerent standardization procedures are needed for samples from diflEerent water environments—e.g., a river water with high turbidity, a clear stream, sea water, or organically polluted lake water. Many different water quality parameters (Table II) and solvents (Table I) are possible to standardize and quantitate LLE. The best choice should be defined for each water type. 

Extraction aims to recover as much as possible of the pollutants from the sampling material. So it is a very fundamental aspect in the analytical process (Yusa et al. 2009). The extraction of POPs in air can be achieved through several established methods (Hawthorne et al. 1989 Chee et al. 1997 Lenicek et al. 2000 Yeo et al. 2003 Christensen et al. 2005). USEPA method 3542 (Soxhlet extraction) has been used to extract semi-volatile organic pollutants from air samples such as filters, XAD-2 resin or polyurethane foam (PUF). Sonication is also one of the extraction methods mostly used to prepare air samples for determination of POPs. All of these traditional procedures have some weaknesses of large volumes... 

The compound specific isotope analysis (CSIA) has been successfully used in the assessment of in situ remediation of contaminated environments, identification of pollutant degradation pathways, or the verification of contaminant sources. In these types of studies, the sensitivity of isotope ratio monitoring GC-MS (irm-GC-MS) is often a limiting factor, since concentrations of organic contaminants in groundwater are very often in the low pg/L range. Hence, in order to be able to routinely use irm-GC-MS techniques in environmental studies, efficient extraction procedures are required. 

Fidalgo-Used et al. [137] have recently reviewed the main extraction and clean-up procedures, published in the last 5 years, applied to the analytical determination of both conventional and emerging persistent organic pollutants (POPs), not exclusively PAHs, in environmental biota (vegetal and animal) samples. Buldini et al. [339] have also reviewed recent sample preparation methods for food analysis. 

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