Organic compounds, volatile, determination

DEVELOPMENT OF CHEMICAL SENSORS FOR VOLATILE ORGANIC COMPOUNDS DETERMINATION... 

One of the most important problems in the analysis of phthalates from water samples is the detection of these compounds in the samples used as blanks. Phthalates have been detected in purified water commonly used in laboratories, including water distilled in a glass distillation apparatus, MUli-Q water, and commercially available water specially for VOC (Volatile organic compounds) determination. Therefore, special caution should be taken with the experimental use of water in laboratories. Some authors have reported the levels of phthalate esters found in the purified water employed in its studies (see Table 28.4). The concentrations found are frequently... 

Tait E, Perry JD, Stanforth SP, Dean JR (2014) Bacteria detection based on the evolution of enzyme-generated volatile organic compounds determination oi Listeria monocytogenes in milk samples. Analytica Chimica Acta. 848 80-7. doi 10.1016/j.aca.2014.07.029. 

KLO Kloskowski, A., Chrzanowski, W., Pilarczyk, M., and Namiesnik, J., Partition coefficients of selected environmentally important volatile organic compounds determined by gas-liquid chromatography with polydimethylsiloxane stationary phase, J. Chem. Thermodyn., 37,21,2005. 

Valerate, determination of 60-65 Vanadium, determination of 151, 228 yl chloride, determination of 350 Volatile organic compounds, determination of 112... 

J. J. Brezinski, Manual on the Determination of Volatile Organic Compounds in Paints, Inks, and Belated Coating Products, 2nd ed., ASTM Manual Series, MNL4, American Society for Testing and Materials, Philadelphia, Pa., 1992. 

In addition to chemicals covered under TRI, many other chemicals are released. For example, the EPA Office of Air Quality Planning and Standards has compiled air pollutant emission factors for determining the total air emissions of priority pollutants (e.g., VOCs, SO, NO, CO, particulates, etc.) from many refinery sources. The EPA Office of Aerometric Information Retrieval System (AIRS) contains a wide range of information related to stationary sources of air pollution, including the emissions of a number of air pollutants which may be of concern within a particular industry. With the exception of volatile organic compounds (VOCs), there is little overlap with the TRI chemicals reported above. 

It is the determination of volatile organic compounds produced from natural products that requires separation techniques that allow isolation of stereoisomers. The most commonly determined groups are the terpene and sesquiterpene species present in essential oils, which are used as key indicators of biological factors such as the growth season, geographic location, climate, etc. These species are also released directly into the atmosphere by very many plants and trees, and make a substantial contribution to global biogeochemical cycles. 

The study of biochemical natural products has also been aided through the application of two-dimensional GC. In many studies, it has been observed that volatile organic compounds from plants (for example, in fruits) show species-specific distributions in chiral abundances. Observations have shown that related species produce similar compounds, but at differing ratios, and the study of such distributions yields information on speciation and plant genetics. In particular, the determination of hydroxyl fatty acid adducts produced from bacterial processes has been a successful application. In the reported applications, enantiomeric determination of polyhydroxyl alkanoic acids extracted from intracellular regions has been enabled (45). 

Modification techniques for activated carhon were used to increase the removal capacity by surface adsorption and to improve the selectivity to volatile organic compounds (VOCs). Modified activated carbons (MACs) were prepared by modifying the purified activated carbon with various acids or bases. The effects of adsorption capacity and modified contents on the textural properties of the MACs were investigated. Furthermore, VOC adsorption and desorption experiments were carried out to determine the relationship between the adsorption capacity and the chemical properties of the adsorbents. High adsorption capacity for the selected VOCs was obtained over lwt%-H3P04/AC (lwt%-PA/AC). As a result, MAC was found to be very effective for VOC removal by adsorption with the potential for repeated use through desorption by simple heat treatment. 

Headspace analysis has also been used to determine trichloroethylene in water samples. High accuracy and excellent precision were reported when GC/ECD was used to analyze headspace gases over water (Dietz and Singley 1979). Direct injection of water into a portable GC suitable for field use employed an ultraviolet detector (Motwani et al. 1986). While detection was comparable to the more common methods (low ppb), recovery was very low. Solid waste leachates from sanitary landfills have been analyzed for trichloroethylene and other volatile organic compounds (Schultz and Kjeldsen 1986). Detection limits for the procedure, which involves extraction with pentane followed by GC/MS analysis, are in the low-ppb and low-ppm ranges for concentrated and unconcentrated samples, respectively. Accuracy and precision data were not reported. 

Hewitt AD, Miyares PH, Leggett DC, et al. 1992. Comparison of analytical methods for determination of volatile organic compounds in soils. Environmental Science and Technology 26 1932-1938. 

Pavlostathis SG, Mathavan GN. 1992. Application of headspace analysis for the determination of volatile organic compounds in contaminated soils. Environ Technol 13 23-33. 

Wakeham SG, Davis AC, Karas JL. 1983. Microcosm experiments to determine the fate and persistence of volatile organic compounds in coastal seawater. Environmental Science and Technology 17 611-617. 

Bakierowska, A.-M., Trzeszqzynski, J. (2003) Graphical method for the determination of water/gas partition coefficients of volatile organic compounds by a headspace gas chromatography technique. Fluid Phase Equil. 213, 139-146. 

Coutant, R.W., Keigley, G.W. (1988) An alternative method for gas chromatographic determination of volatile organic compounds in water. Anal. Chem. 60, 2436-2537. 

Dimethyl sulfide and other volatile organic compounds have been determined in amounts down to 0.1pg/l in seawater in a method described by Watanabe et al. [329]. 

Bellar TA, Lichtenberg JJ (1975) The determination of volatile organic compounds at the ig/l level in water by gas chromatography. US National Technical Information Service report no. 237973/3GA... 

Ashley DL, Bonin MA, Cardinali FL. 1992. Determining volatile organic compounds in human blood from a large sample population by using purge and trap gas chromatography/mass spectrometry. Anal Chem 64 1021-1029. 

This is an alternative technique to headspace analysis for the identification and determination of volatile organic compounds in water. The sample is purged with an inert gas for a fixed period of time. Volatile compounds are sparged from the sample and collected on a solid sorbent trap—usually activated carbon. The trap is then rapidly heated and the compounds collected and transferred as a plug under a reversed flow of inert gas to an external gas chromatograph. Chromatographic techniques are then used to quantify and identify sample components. 

Askari et al. [15] have compared purge and trap, methanol immersion and hot solvent extraction methods for the determination of volatile organic compound in aged soil. These workers found that hot solvent extraction is much more effective than the US Environmental Protection Agency approved purge and trap technique [7, 8]. 

Solid-phase microextraction has also been used for to determine volatile organic compounds in soil [26]. Target compounds were adsorbed directly from a head-space sample above a soil layer onto a fused-silica fibre. Vacuum distillation coupled with gas chromatography-mass spectrometry [27], head-... 

Namiesnik et al. [33] have reviewed the analysis of soils and sediments for organic contaminants. They discuss methods of sample preparation and isolation-preconcentration prior to instrumental determination. Compound classes discussed include volatile organic compounds, polychlorobiphenyls, polyaromatic compounds, pesticides and polychlorodibenzo-p-dioxins and polychlorodibenzofurans. 

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