Organic compounds, extraction using

Supercritical fluid extraction (SFE) and Solid Phase Extraction (SPE) are excellent alternatives to traditional extraction methods, with both being used independently for clean-up and/or analyte concentration prior to chromatographic analysis. While SFE has been demonstrated to be an excellent method for extracting organic compounds from solid matrices such as soil and food (36, 37), SPE has been mainly used for diluted liquid samples such as water, biological fluids and samples obtained after-liquid-liquid extraction on solid matrices (38, 39). The coupling of these two techniques (SPE-SFE) turns out to be an interesting method for the quantitative transfer... 

Uses Chlorine is used for water purification and in decreasing amounts for pulp and paper bleaching. Some is used for metallurgical purposes such as metal extraction. Its largest use is for the production of organic compounds used in plastics, pesticides, herbicides, refrigeration fluids, solvents, and others. 

SPME can be used to extract organic compounds from a solid matrix as long as target compounds can be released from the matrix into the headspace. For volatile compounds, the release of analytes into the headspace is relatively easy because analytes tend to vaporise once they are dissociated from their matrix. For semi-volatile compounds, the... 

The volatile substances were extracted from portions of 0. lg hair using solid-phase micro extraction (SPME). The method uses a fibre coated with an adsorbent that can extract organic compounds from the headspace above the sample. Extracted compounds are desorbed upon exposure of the SPME fibre in the heated injector port of a gas chromatograph (GC). 

Organic solvents at STP and under supercritical conditions are the most common extractants for soil organic matter. Supercritical C02 and, to a lesser extent, N20 have also been used to extract both native and organic contamination from soil. Humus is extracted using aqueous solutions, but otherwise, water is rarely used to extract organic compounds from soil. A list of common soil organic matter extractants is given in Table 12.2. 

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... 

Common surfactants such as Tween, Triton,5 and sodium dihexyl sulfosuc-cinate, among many others, have been used to extract organic compounds from soil. In the field, they have been particularly useful in the remediation of soils contaminated with halogenated organic compounds, oils, and other hydrocarbon compounds [24],... 

Nghiem, L.D., Mornane, P., Potter, I.D., Perera, J.M., Cattrall, R.W. and Kolev, S.D. (2006) Extraction and transport of metal ions and small organic compounds using polymer inclusion membranes (PIMs). Journal of Membrane Science, 281, 7. 

Solvent selection depends largely on the nature of the analytes and the matrix. Although the discussions in Chapter 2 can be used as a guideline to account for the solvent-analyte interactions, the matrix effects are often unpredictable. There is no single solvent that works universally for all analytes and all matrices. Sometimes, a mixture of water-miscible solvents (such as acetone) with nonmiscible ones (such as hexane or methylene chloride) are used. The water-miscible solvents can penetrate the layer of moisture on the surface of the solid particles, facilitating the extraction of hydrophilic organics. The hydrophobic solvents then extract organic compounds of like polarity. For instance, hexane is efficient in the extraction of nonpolar analytes, and methylene chloride extracts the polar ones. 

It should be noted that microwave-assisted extraction (MAE) discussed in this chapter is different from microwave-assisted acid digestion. The former uses organic solvents to extract organic compounds from solids, while the latter uses acids to dissolve the sample for elemental analysis with the organic contents being destroyed. Microwave-assisted digestion of metals is covered in Chapter 5. 

Liquid-liquid extraction (LLE) is the traditional method to extract organic compounds from water. The low molecular weight compounds are transferred from one liquid phase to another immiscible or partially immiscible liquid by shaking them in a separation funnel. LLE is still a common method, but has several drawbacks such as low selectivity, labor intensivity, and the use of large amount, of organic solvent. LLE has been used to extract hydrolysis products of degradable polyesters such as PLA and its copolymers from the buffer solution [115]. 

Alkenes are hydrocarbons with carbon-carbon double bonds. Alkenes are sometimes called olefins, a term derived from olefiant gas, meaning oil-forming gas. This term Introduction originated with early experimentalists who noticed the oily appearance of alkene derivatives. Alkenes are among the most important industrial compounds (see Section 7-6), and many alkenes are also found in plants and animals. Ethylene is the largest-volume industrial organic compound, used to make polyethylene and a variety of other industrial and consumer chemicals. Pinene is a major component of turpentine, the paint solvent distilled from extracts of evergreen trees. Muscalure (cw-tricos-9-ene) is the sex attractant of the common housefly. 

Supercritical fluids such as carbon dioxide can be used as solvents to extract organic compounds from aqueous solutions. In order to achieve recoveries of these products often in low concentration, cosolvents as methanol or other alcohols have been added to improve the solubility and the selectivity of the primary fluid. To optimize the extract recovery, the knowledge of phase equilibria of the ternary system carbon dioxide-methanol-water is required at different temperatures and pressures. 

Analogous principles have been used to extract organic compounds, for example, amino acids [52] and peptides [53,54]. In a basic donor, the extracted compounds are anionic, and thus easily transported through the membrane by the cationic carrier to the acidic acceptor, where the analytes become cationic, and thus non-extractable. 

Comprehensive protocols for the analysis of plastics/polymers need to be developed. In the past analytical protocols included extractions performed with a polar and a non-polar solvent which were used to extract organic compounds from a polymer for subsequent analysis by GC using a flame ionization detector (FID). But FID alone may not be a definitive test, since the identity is based on column retention time, which is not a unique characteristic for many of these complex organic compounds. 

Even ethers of low molecular weight are only slightly soluble in water. Diethyl ether is an excellent solvent for organic compounds. It is widely used to extract organic compounds from plants and other natural sources. 

Flame Photometric Detector (PFPD) or an ICP-MS. The various sample treatment steps, liberation of the compounds, their derivatization and preconcentration via headspace on to a SPME phase, all occur in the same vial, hmiting contamination and loss risks. SPME is a solvent-free sample preparation method in which a fused-sUica fiber coated with a polymeric organic stationary phase is used to extract organic compounds directly from aqueous or gaseous samples.Further GC separation of the compounds and MS, FPD, or ICP-MS detection allows very sensitive determinations. This method will be further referred to as the SPME method. 

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