Organic substances volatile

Heat a small portion of the following substances on an inverted porcelain or stainless steel crucible lid. At first, heat one side of the lid gently so that the heat travels along the lid to the organic substance later heat the lid more strongly. Note carefully in particular [a) the change in appearance, (b) whether readily inflammable, (r) any odour produced, (d) wliether a non-volatile residue is left. 

Essential oils (Section 26 7) Pleasant smelling oils of plants consisting of mixtures of terpenes esters alcohols and other volatile organic substances Ester (Sections 4 1 and 20 1) Compound of the type... 

IR SPECTROMETRICAL DETERMINATION OF VOLATILE ORGANIC SUBSTANCES IN WATERS AFTER EXTRACTION INTO GASEOUS PHASE... 

Provide annual estimates of all point and fugitive emission sources (tons per year) of hazardous substances, volatile organic compounds (VOCs), heavy metals and fossil fuel products (for example, NOx and SOx) that are released to the environment. 

Supercritical fluid extraction (SFE) has been extensively used for the extraction of volatile components such as essential oils, flavours and aromas from plant materials on an industrial as well as an analytical scale (61). The extract thus obtained is usually analysed by GC. Off-line SFE-GC is frequently employed, but on-line SEE-GC has also been used. The direct coupling of SEE with supercritical fluid chromatography (SEC) has also been successfully caried out. Coupling SEE with SEC provides several advantages for the separation and detection of organic substances low temperatures can be used for both SEE and SEC, so they are well suited for the analysis of natural materials that contain compounds which are temperature-sensitive, such as flavours and fragrances. 

Chodola GR, Biswas N, Bewtra JK, et al. 1989. Fate of selected volatile organic substances in aqueous environment. Wat Pull Res J Can 24 119-142. 

Another challenge is to develop methods to replace the volatile organic solvents that are used in many industrial procedures. One choice is water as a solvent it is easily repurified, and has a harmless vapor. Another choice is supercritical carbon dioxide, a good solvent for many organic substances. It is not as innocuous as is water, but carbon dioxide can be easily recovered and reused. It is currently used to remove caffeine from coffee, and is being developed as a dry-cleaning solvent to replace organic solvents (Chapter 9). 

In addition to these three main groups of organic components, volatile fatty acids (VFAs), amino acids, detergents, humic substances, organic fibers, etc., have been found. 

Mean values for concentrations of volatile organic substances in the Glatt infiltration system. (From Schwarzenbach et al., 1983)... 

Pharmaceutical chemicals belonging to the domain of inorganic as well as organic substances containing readily volatile matter for which the various official compendia prescribe limits of non-volatile matter. It is pertinent to mention here that the Pharmacopoeia usually makes a clear distinction between substances that are readily volatile and substances that are volatile upon strong ignition, for instance ... 

Coleman WE, Lingg RD, Melton RG, et al. 1976. The occurrence of volatile organics in five drinking water supplies using gas chromatography/mass spectrometry. In Keith L, ed. Analysis and identification of organic substances in water. Ann Arbor, MI Ann Arbor Science, 305-327. 

Kersten W, Reich T (2003) Non-volatile organic substances in Hamburg indoor dust. Gefahrst Reinhalt L 63 85-91... 

Bozzelli JW, Kebbekus BB. 1979. Analysis of selected volatile organic substances in ambient air. Report to New Jersey Department of Environmental Protection, Program on Environmental Cancer and Toxic Substances, by New Jersey Institute of Technology, Air Pollution Research Laboratory. 

Evans, M., et al, The Practical Application of the Praton Diffusion Sampler for the Measurement of Time-Weighted Average Exposure to Volatile Organic Substances in Air,... 

Expls prepd by treating porous AN grains with vapors of volatile organic substances. Immediately after the adsorption of vapors, the vapors are sealed by a coating with small amts of waxes)... 

Box 20.2 summarizes the numerical evaluation of this expression with experimental data obtained for trichlorofluoromethane (CFC-11) by Zheng et al. (1998) (see also Table 20.3). The behavior of CFC-11 is typical for many volatile organic substances. The relative effect of temperature on vIW decreases from 4 percent per Kelvin at 5°C and low wind speed to 2.4 percent per Kelvin at 25°C and high wind speed. The total increase of vlw between 5°C and 25°C amounts to the factors 2 (low wind speed) and 1.7 (high wind speed), respectively. 

The use of supercritical fluid carbon dioxide to extract low levels of organic substances from water was investigated for 23 different compounds. In general, compounds that were volatile and/or not highly soluble in water were readily extracted under the conditions used. Compounds of higher water solubility did not show evidence of extraction. In addition, those materials that tended to precipitate or form more soluble species under acidic conditions were not extracted. 

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