Extraction of organic compounds

These species are also unusual iu that they are extremely hydrophobic anions which form very strong conjugate acids. This unique combination of features leads to a number of potential uses such as the extraction of organic compounds from extremely dilute solutions and the isolation of metal cations, including the quantitative separation of radionucUdes, eg, Cs (192). 

Figure 2.21 shows the on-line extraction gas chromatogram of 2.25 ml of water spiked at 5 ppb levels with 14 different organic pollutants (40). In this case, the authors concluded that wall-coated open tubular traps (thick-film polysiloxane phases) can be used for the on-line extraction of organic compounds from water. However, when using swelling agents such as pentane, non-polar analytes can be trapped quantitatively, while for more polar compounds chloroform is the most suitable solvent. 

Carbon dioxide is the most common inorganic extractant used for the extraction of organic compounds in soil. Under pressure, it remains in the liquid state and can be used to extract organic compounds from soil. When the pressure is released, the carbon dioxide becomes a gas and is thus removed from the extracted components. An additional benefit is that liquid carbon dioxide is converted to gas at relatively low temperatures, thus limiting the loss of... 

In many cases, extraction of organic compounds requires that the extract be cleaned up before analysis. This may be as simple as centrifugation, but it may also involve concentration or evaporation of the solvent. Another approach is to absorb the analyte of interest on an absorbant and subsequently to extract it into another solvent. This may be necessary to ensure that the extract is compatible with the analytical procedure to be used. 

Lopez-Avila V, Young R, Beckert WF. Microwave-assisted extraction of organic-compounds from standard reference soils and sediments. Anal. Chem. 1994 66 1097-1106. 

Although selective extraction of organic compounds appears to be an attractive option, the different types of adsorption sites on solid phases require an exhaustive technique to recover the maximum amount of the analyte from the... 

G. Schill, Selective extraction of organic compounds as ion-pairs and adducts , Talanta, 1975,22, 1017. 

The classical techniques for the solvent extraction of chemical compounds from vegetable material are based upon the correct choice of solvent and conditions e. g. heating or agitation. A range of commercially important pharmaceuticals, flavours and colourants are now derived from vegetable sources. It has been shown that the solvent extraction of organic compounds contained within the body of plants and seeds is significantly improved by the use of power ultrasound [25]. 

This chapter comprises some selected excerpts taken from a comprehensive two-volume text on the subject coauthored by the author [1]. It specifically addresses the extraction of metals, but many of the (general) conclusions are equally valid for the extraction of organic compounds, with appropriate modifications. 

The purpose of seeking a concentrated strip solution is to reduce the energy required to recover the product from the strip solution. In the case of metal salts, precipitation, electrolysis, direct reduction, and a host of other techniques may be used to generate the final product. In the case of the extraction of organic compounds, distillation, crystallization, or similar separation methods are used. In each case, the more concentrated the strip solution, the less energy is required to recover the desired components. 

The separation of organic mixtures into groups of components of similar chemical type was one of the earliest applications of solvent extraction. In this chapter the term solvent is used to define the extractant phase that may contain either an extractant in a diluent or an organic compound that can itself act as an extractant. Using this technique, a solvent that preferentially dissolves aromatic compounds can be used to remove aromatics from kerosene to produce a better quality fuel. In the same way, solvent extraction can be used to produce high-purity aromatic extracts from catalytic reformates, aromatics that are essentially raw materials in the production of products such as polystyrene, nylon, and Terylene. These features have made solvent extraction a standard technique in the oil-refining and petrochemical industries. The extraction of organic compounds, however, is not confined to these industries. Other examples in this chapter include the production of pharmaceuticals and environmental processes. 

Extraction of Organic Compounds from the Soil. Soil biochemicals that are free or absorbed loosely, but not bound to the humus, were extracted by the following procedures ... 

Given all these attractive features, it is easy to understand the increasing interest in the application of ILs in solvent extraction. The review gives an introduction into the rapidly growing area it focuses on the extraction of organic compounds, metal ion extraction being considered in Chapter 10 of this book. 

Extraction of organic compounds from aqueous solutions... 

Chapter nine Liquid-liquid extraction of organic compounds... 

If the ratio be unity, the concentrations of the solute in each solvent will be the same if the ratio be far removed from unity, a correspondingly large proportion of the solute will be found in the one solvent which can be utilized to extract the Soln. from the other solvent. E.g. ether will remove ferric chloride from its aq. soln., and since many other chlorides are almost insoluble in ether, the process is utilized in analysis for the separation of iron from the other elements the solubility of cobalt thiocyanate in ether is utilized for the separation of cobalt perchromic acid is similarly separated from its aq. soln. by ether molten zinc extracts silver and gold from molten lead the extraction of organic compounds from aq. soln. by shaking out with ether or other solvent is much used in organic laboratories. 

On the basis of this work, it appears that the supercritical fluid carbon dioxide extraction of organic compounds present in water at low levels may be useful only in the case of volatile organic species. Even for these compounds, however, if efficient recovery of the compounds is desired and appropriate, certain limitations of existing trapping techniques remain to be overcome. 

Figure 28-14b shows the extraction of organic compounds from dust collected with a vacuum cleaner from door mats at the chemistry building of Ohio State University. The chromatogram of the extract in Figure 28-14c exhibits myriad organic compounds that you and I inhale in every breath. 

Martin-Esteban A (2001) Molecularly imprinted polymers new molecular recognition materials for selective solid-phase extraction of organic compounds. Fresenius J Anal Chem 370(7) 795-802... 

The extraction of organic compounds from water using ionic liquids takes place in the same way as with traditional organic solvents. 

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