Extractants extraction/soils, sediments

PAHs in soil may partition into soil organic matter (SOM) or adsorb on soil minerals. The sorptive properties of SOM fractions for organic contaminants in soil play an important role on the transportation of PAHs in soil. Xiao et al. (2004) has reported that soil/sediment organic matter can be fractionated into four fractions with a combined wet chemical procedure and that kerogen and black carbon (BC) are major SOM components in soil/sediment samples collected from the industrialized suburban areas of Guangzhou, China. Phenanthrene and naphthalene were used as the sorbates to study PAH s sorption isotherms on four original and four Soxhlet-extracted soil/sediment samples, 15 isolated SOM fractions, and a char as the sorbents. The sorption isotherms of phenanthrene and naphthalene on all the sorbents were variously nonlinear. The particulate kerogen and black carbon (KB) fractions... 

Preparation of soil—sediment of water samples for herbicide analysis generally has consisted of solvent extraction of the sample, followed by cleanup of the extract through Uquid—Uquid or column chromatography, and finally, concentration through evaporation (285). This complex but necessary series of procedures is time-consuming and is responsible for the high cost of herbicide analyses. The advent of soUd-phase extraction techniques in which the sample is simultaneously cleaned up and concentrated has condensed these steps and thus gready simplified sample preparation (286). 

For pesticide residue immunoassays, matrices may include surface or groundwater, soil, sediment and plant or animal tissue or fluids. Aqueous samples may not require preparation prior to analysis, other than concentration. For other matrices, extractions or other cleanup steps are needed and these steps require the integration of the extracting solvent with the immunoassay. When solvent extraction is required, solvent effects on the assay are determined during assay optimization. Another option is to extract in the desired solvent, then conduct a solvent exchange into a more miscible solvent. Immunoassays perform best with water-miscible solvents when solvent concentrations are below 20%. Our experience has been that nearly every matrix requires a complete validation. Various soil types and even urine samples from different animals within a species may cause enough variation that validation in only a few samples is not sufficient. 

Lopez-Avila V, Dodhiwala NS, Beckert WF. 1991. Method for the supercritical fluid extraction of soils/sediments. Las Vegas, NV U.S. Environmental Protection Agency, Environmental Monitoring Systems Laboratory. EPA/600/S4-90/026. 

Precautions should be taken to avoid disulfoton loss from stored water, soil, sediment, crop, and vegetable samples (Belisle and Swineford 1988 Miller etal. 1981 Munch and Frebis 1992 Szeto and Brown 1982). Disulfoton, disulfoton sulfone, and disulfoton sulfoxide were not recovered from spiked well water stored 14 days however, sample extracts were stable for 14 days (84-92% recovery) (Munch and Frebis 1992). In most environmental samples, disulfoton will be present along with its environmental transformation products, disulfoton sulfone, disulfoton sulfoxide, disulfoton oxon, disulfoton oxon sulfone, and disulfoton oxon sulfoxide (Szeto and Brown 1982). Disulfoton and its oxon are very unstable, and they oxidize rapidly to the corresponding sulfoxides. The sulfoxides are relatively stable, but they oxidize slowly to their sulfones, which are most stable (Szeto and Brown 1982). Several methods for determining the metabolites of disulfoton in environmental samples are included in Table 6-2. 

The extraction of aromatic chlorophenols (e.g., chloroguaiacols, chloro-catechols) is complicated by the different sorption processes that control their binding within the soil-sediment structure [411-413]. The free, physically adsorbed chlorophenolics can be extracted with solvent, but this may only account for 1-5% of the total concentration of these pollutants in the sediment. Martinsen et al. [414] found that -hexane or cyclohexane and iso-propanol... 

Soil, sediment Sample mixed with anhydrous powdered Na2S04, solvent extracted ultrasonically, extract subjected to GPC if necessary, extract concentrated GC-MS (EPA-CLP Method) 330 pg/kg NG EPA 1987... 

For most analyses, it is necessary to separate the analytes of interest from the matrix (i.e., soil, sediment, and water). Extraction of analytes can be performed using one or more of the following methods (1) extracting the analytes into a solvent (2) heating the sample, as may be necessary to remove the solvent and for the analysis of volatile compounds and (3) purging the sample with an inert gas, as is also used in the analyses of volatile compounds. 

Waste water, soil, sediment, solid waste Extraction (liquid-liquid, Soxhiet, sonication) with organic solvent such as dichloromethane, removal of water, volume reduction. GC/MS (EPA method 8270) 20 g/L (ppb) for wastewater 1,300 g/kg (ppb) for low soil, sediment 110 at 100 g/L (100 ppb) EPA 1986a... 

Johnston AE, Goulding KWT, Poulton PR (1986) Soil acidification during more than 100 years under permanent grassland and woodland at Rothamsted. Soil Use Manage 2 3-10 Kahn SU (1982) Bound pesticides residues in soil and plant. Residue Rev 84 1-25 Kan AT, Chen W, Tomson MB (2000) Desorption kinetics from neutral hydrophobic organic compounds from field contaminated sediment. Environ Pollution 108 81-89 Kang SH, Xing BS (2005) Phenanthrene sorption to sequentially extracted soil humic acids and humans. Environ Sci Technol 39 134-140... 

Chemical separation techniques can be used to reduce spectral interferences and concentrate the analyte. These techniques include solvent extraction(39) and hydride generation(39, 46, 47). At Imperial College, the hydride generation technique is being used on a daily basis(46) for the analysis of soils, sediments, waters, herbage, and animal tissue. The solvent extraction technique is ideally suited for automated systems where the increased manipulation is carried out automatically, and a labor intensive step and sources of contamination are avoided. 

Soil, sediment Extract sample with CH2CI2 GC/MS 330 ppb No data EPA, 1988a o,p... 

Determination of total fluoride in soil, sediments, oxides and other raw materials requires complete decomposition of the sample. Accumulation of fluoride in soil can be studied by employing appropriate extraction procedures. 

T0480 Linatex, Inc., Soil/Sediment Washing Technology T0487 Louisiana State University, Colloidal Gas Aphron T0490 M4 Environmental, L.P., Catalytic Extraction Process... 

T0718 Smith Technology Corporation, Two-Phase Vacuum Extraction T0719 Soil/Sediment Washing—General... 

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. 

The Basic Extractive Sludge Treatment (B.E.S.T. ) process is an ex situ solvent extraction technology. The B.E.S.T. process uses one or more secondary or tertiary amines, such as diisopropylamine, to separate contaminants from soil, sediment, and sludge. This technology is applicable to most organics or oily contaminants, including polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), pesticides, herbicides, dioxins, furans, and other organic compounds. 

Thermal desorption is a technology that physically separates volatile and some semivolatile contaminants from contaminated media. In thermal desorption, heated air is used to volatilize contaminants at temperatures below those used for incineration. There are both in situ and ex situ applications of the technology. Ex situ treatments typically are used to remediate soil, sediments, sludges, and filter cakes. In situ applications of the technology use injected steam, thermal blankets, or heat supplied by electrodes to volatilize contaminants, which are then removed using extraction wells. 

Waters, soils, sediments, sludges <30% solids Dilution to 1% solids and extraction with methylene chloride, concentration using K-D. Clean up using GPC and SPE. GC/FPD (Method 622) 3.8 ng/L 60-120 EPA 1992c... 

The extraction and clean-up methods used for the recovery of organophosphorus derivatives do not differ basically from those applied to other groups of substances. However, because of the high toxicity of the compounds involved, the techniques must be extremely sensitive and able to detect sub-nanogram amounts. A number of reviews have been published on the subject164-171. As previously mentioned, the compounds to be analysed may be found in living matter as well as in soil, sediments, water and air the experimental methods vary accordingly. 

Protocols for preparing six environmental sample types prior to the Ames Salmonella assay were proposed at a recent panel discussion sponsored by the U.S. Environmental Protection Agency (USEPA) and the U.S. Army. Air particles, soil-sediment, and solid waste are extracted with dichloromethane, concentrated, and solvent exchanged into dimethyl sulfoxide (DMSO). Organics in water and waste water are absorbed onto XAD columns, then eluted with hexane-acetone, solvent reduced, and exchanged into DM SO. Nonaqueous liquids are assayed directly and as concentrates before they are solvent exchanged to DMSO. If bacterial toxicity or lack of dose response is observed in the Ames assay of extracts, the extracts are fractionated prior to solvent exchange. These are interim methods and have not been subjected to policy review of the USEPA or the U.S. Army. 

There are, however, a number of stumbling blocks with the PCR assay. Very close attention must be paid to pipetting technique so that stocks (of nucleotide, primers, buffers) do not become contaminated with target DNA. Controls are de rtgueur, and must be run at every amplification. Important, too, is the nature of the template. Because environmental samples usually contain soil, sediment, aquifer material, and/or plant parts, and because these materials also contain substances that interfere with and inactivate the PCR assay, such as humic acids, the bacterial DNA must be extracted free of these contaminating substances. Other compounds, such as metals, also inhibit the reaction, necessitating purification of the DNA prior to amplification. 

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