Soil ethanol extractions

A major metabolite was detected in the ethanol extract of 2,7-dichlo-rodioxin-treated soils. The metabolite was less mobile than DCDD in benzene-acetonitrile on TLC. The metabolite was eluted from the silica gel and methylated with diazomethane. The methylated metabolite was rechromatographed in benzene and migrated to the solvent front, suggesting a polar group on the non-methylated metabolite. 

Influence of Ethanol Extracts of Soil and Fescue Plants... 

In order to determine if inhibiting substances were present in soil in which tall fescue was growing, soil was dug from the field on March 20. Fescue roots were separated from the soil and saved along with leaves. Two hundred grams (fresh weight) each of fescue leaves and roots were leached overnight in 1,000 ml of ethanol and then filtered. Four hundred grams of the fescue soil was extracted... 

This technique has been applied [47] to the determination of ethanol, methylethyl ketone, paraldehyde and acrolein in soils. Following extraction of the soil with methanol and gas purging the purge gas is trapped on a Tenax column. The purgate obtained by heating the Tenax column is analysed by gas chromatography and/or mass spectrometry. 

Soil Extraction. Granite Reef soil, 100 g, was treated with 30 mL of a 5% isopropanol solution of the partially hydrogenated tallow fatty acid-DETA reaction product and then air dried overnight and finally in a vacuum oven at 50°C for 1 hr to remove residual isopropanol. On the following day the treated soil was extracted with ethanol 8 hr in the Soxhlet apparatus. The extracted solvent was evaporated recovering 1 g residue. As a control experiment, untreated soil, 100 g, was also extracted 8 hr with ethanol. 

Experiments conducted with a water-diluted 100% ethanol extract of PCP-contaminated soil. Experiments conducted with a 1 3 1 v/v solution of methanol/water/acetone. Araclor 1254 and 1260 are PCB mixtures containing 54 and 60% Cl by weight, respectively. 

Polysaccharides were extracted from various British soils with buffers, in yields of O.Or) to 0.15% of the soils. No further details of the isolation procedure were given. More recently, soils were extracted with a phosphate buffer of pH 7, and the polysaccharides were recovered from the dialyzed and concentrated extract by precipitation with ethanol." This procedure extracted less non-dialyzable, non-carbohydrate material than those employing dilute alkali or sodium pyrophosphate. Yields were about the same as with hot-water extraction, but the polysaccharides isolated by means of phosphate buffer had a higher viscosity. 

Paclitaxel and related compounds have also been found in various Taxus species in addition to the Pacific yew, occurring in roots, stems, wood, and needles as well as bark. Yew extracts contain a complex mixture of taxanes, with paclitaxel usually constituting less than 20% of the total taxanes. Isolation of paclitaxel from these mixtures is a difficult purification problem and contributed to the slow development of this compound as a drug. The most valuable material in this mixture for semisynthesis is 10-deacetylbaccatin-III. Microbial strains were isolated from soil samples containing C-13 deacylase and C-lO-deacetylase enzyme activities that are able to convert mixtures of taxanes to 10-deacetylbaccatin-III, thereby increasing the amount and ease of isolation of this precursor for semisynthesis (Scheme 17.14). Treatment of ethanol extracts, prepared either from whole plants of a variety of renewable yew cultivars or from material derived from the bark of... 

The first use of supercritical fluid extraction (SFE) as an extraction technique was reported by Zosel [379]. Since then there have been many reports on the use of SFE to extract PCBs, phenols, PAHs, and other organic compounds from particulate matter, soils and sediments [362, 363, 380-389]. The attraction of SFE as an extraction technique is directly related to the unique properties of the supercritical fluid [390]. Supercritical fluids, which have been used, have low viscosities, high diffusion coefficients, and low flammabilities, which are all clearly superior to the organic solvents normally used. Carbon dioxide (C02, [362,363]) is the most common supercritical fluid used for SFE, since it is inexpensive and has a low critical temperature (31.3 °C) and pressure (72.2 bar). Other less commonly used fluids include nitrous oxide (N20), ammonia, fluoro-form, methane, pentane, methanol, ethanol, sulfur hexafluoride (SF6), and dichlorofluoromethane [362, 363, 391]. Most of these fluids are clearly less attractive as solvents in terms of toxicity or as environmentally benign chemicals. Commercial SFE systems are available, but some workers have also made inexpensive modular systems [390]. 

In this method the soil extract and the blank and standards are evaporated almost to dryness by gentle heating and then cooled in an ice pack. Five millilitres of 80% sulfuric acid and then 1 ml of a 2% ethanolic solution of 3,4-xylenol are added. This solution is transferred to a separatory funnel with 80 ml ice-cooled distilled water. Toluene (10 ml) is added to the isolated toluene extract, and 5 ml of 1% sodium hydroxide is added to convert the phenol to the phenoxide. The lower aqueous phase is separated and evaluated spectropho-tometrically at 432 nm using matched silica cells with distilled water in the reference cell. 

In an indirect method for determining sulfate in soil extracts, Little et al. [68] precipitate sulfate as the lead salt in 40% ethanol medium. Unconsumed sol-... 

Samples of dried and ground (0.3 mm) energy crops (mimosa, sericea, kudzu, arunzo, switchgrass, velvet bean, and castor) were kindly supplied by Dr. David Bransby of the Department of Agronomy and Soils at Auburn University. To perform an extraction, 2 g of the selected energy crop was mixed with 60 mL of solvent (either water, 60% methanol in water, or 60% ethanol in water) and blended in a standard household blender for 1 min... 

Rapeseed methyl ester (RME) is another alternative biofuel that can be used in diesel engines. RME has the advantages that it is renewable compared to diesel, non-toxic and less flammable compared with many other fuels, like ethanol. RME has the same cetane number, viscosity and density as diesel, contains no aromatic compounds and is biologically degradable with minor contamination in soil. RME can be produced from vegetable oils, but is mostly produced from rapeseed oil by pressing of the seeds or by extraction. Up to 3 tons of rapeseed can be produced from one hectare. The fatty acids in rapeseed oil are mostly oleic acid, linoleic acid and linolenic acid. The oil is pressed from the plant and after some purification allowed to react with methanol in the presence of potassium hydroxide as a catalyst, to produce a methyl ester, see Figure 6.6. 

Pure water at a high pressure and temperature was the solvent used as extractant in most applications. However, the addition of a modifier [157,173] or a co-extractant [47] can dramatically improve the extraction of some substances. Such is the case with the extraction of nonylphenol polyethoxy carboxylates from industrial and municipal sludges, where recovery was increased by more than 30% in the presence of 30% (v/v) ethanol in the water used as leaching agent [157]. Because of the hydrophobic nature of PAHs, the increased dielectric constant of water at a high temperature did not suffice to ensure quantitative extraction from soil. However, as can be seen from Fig. 6.14, the addition of a co-extractant (viz. sodium dodecyl sulphate, SDS, which forms charged micelles) dramatically improved the extraction of these hydrophobic compounds also, it substantially reduced the extraction time and enabled the quantitative recovery of benzo(a)-acenaphthene [47]. 

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