Organic solvent extractants

The development of the novel Davy-McKee combined mixer—settler (CMS) has been described (121). It consists of a single vessel (Fig. 13d) in which three 2ones coexist under operating conditions. A detailed description of units used for uranium recovery has been reported (122), and the units have also been studied at the laboratory scale (123). AppHcation of the Davy combined mixer electrostatically assisted settler (CMAS) to copper stripping from an organic solvent extraction solution has been reported (124). 

Manufacture. Cyanoacetic acid and cyanoacetates are iadustrially produced by the same route as the malonates starting from a sodium chloroacetate solution via a sodium cyanoacetate solution. Cyanoacetic acid is obtained by acidification of the sodium cyanoacetate solution followed by organic solvent extraction and evaporation. Cyanoacetates are obtained by acidification of the sodium cyanoacetate solution and subsequent esterification with the water formed being distilled off. Other processes reported ia the Hterature iavolve the oxidation of partially oxidized propionittile [107-12-0] (59). Higher esters of cyanoacetic acid are usually made through transesterification of methyl cyanoacetate ia the presence of alumiaiumisopropoxide [555-31-7] as a catalyst (60). 

Polyethers are usually found in both the filtrate and the mycelial fraction, but in high yielding fermentations they are mosdy in the mycelium because of their low water-solubiUty (162). The high lipophilicity of both the free acid and the salt forms of the polyether antibiotics lends these compounds to efficient organic solvent extraction and chromatography (qv) on adsorbents such as siUca gel and alumina. Many of the production procedures utilize the separation of the mycelium followed by extraction using solvents such as methanol or acetone. A number of the polyethers can be readily crystallized, either as the free acid or as the sodium or potassium salt, after only minimal purification. 

Cell wall lysed with organic solvent extraction... 

A proteinaceous particulate material has been described that is effective as an oil spill-dispersant composition [1450]. The material is a grain product (such as oats) from which lipids are removed through organic solvent extraction. When such compositions are applied to an oil spill, they will adsorb oil, emulsify it, and finally, disperse it. Moreover, the compositions are substantially nontoxic. 

Extraction of residues from soil samples is much more difficult than their extraction from plant or water samples. The pesticide residues in the soil exist often in several forms as bound residue , which may affect the extraction efficiency of pesticides from the soil. Then, various extraction methods such as organic solvent extraction, Soxhlet extraction, sonication extraction, microwave dissolution and supercritical fluid extraction (SEE) are used. Some extraction methods are described in the following. 

Thus, organic solvent extraction methods for the extraction of pesticides from water samples can be replaced by the SPE method using Ci8 and PS-2. Ethobenzanid, clomeprop, naproanilide and their acidic metabolites are determined by a multi-residue analytical method using Cig or PS-2 cartridge extraction after acidification of the water samples with hydrochloric acid or other acidic media, followed by HPLC or LC/MS detection. 

Florisil column chromatography is effective in eliminating interfering substances in soil. The organic solvent extracts from soil samples are charged to a column plugged with Florisil which has been activated at 130 °C overnight before use. The effluents from the column with a mixed solvent such as n-hexane-acetone are concentrated to... 

Organic solvent extraction. Two analytical methods for acetamiprid have been developed One method is for the parent only and the other determines the total residue of the parent and its metabolites (lM-1-2, lM-1-4 and lC-0). Air-dried soil (20-g equivalent dry soil) is weighed into a centrifuge tube and imidacloprid residue is extracted with 100 mL of methanol-0.1M ammonium chloride (4 1, v/v) using a mechanical shaker for about 30 min. After shaking, the tube is centrifuged at 8000 rpm for 2 min. The supernatant is filtered and the analysis of the soil residue is carried out in the same manner as described above for the parent compound. 

Solvent Extraction Aqueous sample is partitioned with an immiscible organic solvent. Extraction efficiency depends on the affinity of the solute for the organic solvent. All sample types Samples with a high affinity for water are not extracted. Extractions can be performed by a simple single equilibration or by multiple equilibrations with fresh solvent. Solvent impurities concentrated along with sample. 

Some Palmer amaranth samples prepared at SRRC were first extracted with hexane (HX), rather than PE. The organic solvent extracts were supplied for bioassay in the form of oils or solids remaining after solvent removal in vacuo. After each extraction step aliquots of the crude extracts from the roots, stems, or leaves (and thyrses) were evaluated for seed germination regulatory activity. 

Table VIII. Effect of Ragweed Organic Solvent Extracts on Lettuce and Carrot Germination...

Not all of the classical extraction processes are suitable for ultrasonic enhancement. For example, among the existing techniques used to obtain bio-active extracts from plant material (direct distillation, water steam distillation, organic solvent extraction, maceration, cold/hot fat extraction, etc.) [195] the water steam distillation is not amenable to ultrasonic enhancement. 

A single SFE/ESE instrument may perform (i) pressurised C02 (SFE), (ii) pressurised C02/modifier and (iii) pressurised modifier (i.e. ASE /ESE , organic solvent) extractions. The division between SFE and ASE /ESE blurs when high percentages of modifier are used. Each method has its own unique advantages and applications. ESE is a viable method to conduct matrix/analyte extraction provided a solvent with good solvating power for the analyte is selected. Sample clean-up is necessary for certain matrix/analyte combinations. In some circumstances studied [498], SFE may offer a better choice since recoveries are comparable but the clean-up step is not necessary. 

Determination of trace metals and other elements in aqueous or organic solvent extract solutions... 

In addition, a novel fluorous support has been developed recently as an alternative to traditional polymer supports and applied successfully to oligosaccharide synthesis in combination with the trichloroacetimidate method [541]. Each intermediate in the fluorous oligosaccharide synthesis [542,543] could be obtained by simple fluorous-organic solvent extraction, and the reactions could be monitored by TLC, NMR and MS, in contrast to solid-phase reactions. Moreover, the new liquid-phase technique is anticipated to be easily applicable to the large-scale synthesis. 

Farrington and Quinn [17] gave details of procedures involving saponification and extraction. Between 32 and 65% of the fatty acids were not released from sediments by organic solvent extraction. 

Tecator [34] has described an apparatus, the Soxtec System HT6, for the organic solvent extraction of organics from soils preparatory to further analysis. 

Nowicki et al. [51] point out that in the development of a Soxhlet sample preparation technique for sediment samples, the empty paper Soxhlet thimbles contained organic contaminants which adversely affected results. Glass thimbles were tried and found to be satisfactory. The authors detail the identification of organics solvent-extracted from paper and glass Soxhlet thimbles, and discuss the stability for multiple use of the two materials for trace organic sample preparation. 

Tilapia fish (25-35 mm length) were selected as the test organisms because of their ability to live in adverse conditions. Five juvenile fish were acclimated in a glass tank containing 2 liters of clean, conditioned water. The extract was mixed with the water in the experimental medium. The tanks were not aerated nor the fish fed during the 24-hr test. Bioassays of the organic solvent extracts were performed at a concentration of 0.1 ppt. 

Vanadium usually is recovered from its ores by one of two processes, (1) leaching raw mineral with hot dilute sulfuric acid, and (2) roasting ore with common salt to convert vanadium into water soluble sodium vanadates. In the sulfuric acid leaching process, vanadium is extracted from acid leach liquors by solvent extraction with an aliphatic amine or an alkyl phosphoric acid in kerosene. The organic solvent extract then is treated with an aqueous solution of ammonia in the presence of ammonium chloride to convert vanadium into ammonium metavanadate. Alternatively, the organic extract is treated with dilute sulfuric acid or an aqueous solution of soda ash under controlled conditions of pH. Vanadium is precipitated from this solution as a red cake of sodium polyvanadate. 

Alternatively, solvent partition or countercurrent techniques may be applied. In order to obtain an isoflavonoid-rich fraction from Erythrina species (Leguminosae) for further purification work, an organic solvent extract was dissolved in 90% methanol and first partitioned with hexane. The residual methanol part was adjusted with water to 30% and partitioned with t-butyl methyl ether-hexane (9 1). This latter mixture was then chromatographed to obtain pure compounds. ... 

Multivariate source. apportionment models have been developed for two fractions of respirable particulate organic matter which together constitute about 90% of the total organic solvent-extractable mass. The independent variables used for developing the models were trace metals, water-soluble sulfate and meteorological variables. Two of the three POM fractions extracted sequentially with cyclohexane (CYC), dlchloromethane (DCM) and acetone (ACE) were used as individual dependent variables. 

---