Benzene, toluene, ethylbenzene, xylene

Quantitative analysis. Spectroscopic analysis is widely used in the analysis of vitamin preparations, mixtures of hydrocarbons (e.y., benzene, toluene, ethylbenzene, xylenes) and other systems exhibiting characteristic electronic spectra. The extinction coefficient at 326 mp, after suitable treatment to remove other materials absorbing in this region, provides the best method for the estimation of the vitamin A content of fish oils. 

Monomeric aromatic hydrocarbons Benzene, toluene, ethylbenzene, xylene (BTEX) Oil industry (P,D) Gasoline stations (P) Manufactured gas plants (P,D) 6 [43]... 

Biopract provides technological products and processes for industry, agriculture, and environment. They not only produce technical enzyme preparations but also develop enzymes for applications in agriculture, food, and textile industry as well as in environmental technologies. On the later, bioremediation has been an area of service delivery from Biopract. Their activities regards microbial preparations for the bioremediation of organic contaminants (mineral oil (MKW), polycyclic aromatic hydrocarbons (PAH), benzene, toluene, ethylbenzene, xylene (BTEX), methyl-tert-butyl ether (MTBE), volatile organic hydrocarbons (VOC), and dimethyl sulfoxide (DMSO)). 

Day TPHab Benzene Toluene Ethylbenzene Xylenes TPHab Benzene Toluene Ethylbenzene Xylene... 

There are indications that pure naphthalene (a constituent of mothballs, which are, by definition, toxic to moths) and alkylnaphthalenes are from three to 10 times more toxic to test animals than are benzene and alkylbenzenes. In addition, and because of the low water solubility of tricyclic and polycyclic (polynuclear) aromatic hydrocarbons (i.e., those aromatic hydrocarbons heavier than naphthalene), these compounds are generally present at very low concentrations in the water-soluble fraction of oil. Therefore, the results of this smdy and others conclude that the soluble aromatics of crude oil (such as benzene, toluene, ethylbenzene, xylenes, and naphthalenes) produce the majority of its toxic effects in the enviromnent. 

Immunoassay methods correlate total petroleum hydrocarbons with the response of antibodies to specific petroleum constituents. Many methods measure only aromatics that have an affinity for the antibody, benzene-toluene-ethylbenzene-xylene, and PAH analysis (EPA 4030, Petroleum Hydrocarbons by Immunoassay). 

Test methods that analyze individual compounds (e.g., benzene-toluene-ethylbenzene-xylene mixtures and PAHs) are generally applied to detect the presence of an additive or to provide concentration data needed to estimate environmental and health risks that are associated with individual compounds. Common constituent measurement techniques include gas chromatography with second-column confirmation, gas chromatography with multiple selective detectors, and gas chromatography with mass spectrometry detection (GC/MS) (EPA 8240). 

A number of different testing kits based on immunoassay technology are available for rapid field determination of certain groups of compounds, such as benzene-toluene-ethylbenzene-xylene (EPA 4030) or polynuclear aromatic hydrocarbons (EPA 4035, Polycyclic Aromatic Hydrocarbons by Immunoassay). The immunoassay screening kits are self-contained portable field kits that include components for sample preparation, instrumentation to read assay results, and immunoassay reagents. 

One method (EPA 8020) that is suitable for volatile aromatic compounds is often referred to as benzene-toluene-ethylbenzene-xylene analysis, although the method includes other volatile aromatics. The method is similar to most volatile organic gas chromatographic methods. Sample preparation and introduction is typically by purge-and-trap analysis (EPA 5030). Some oxygenates, such as methyl-f-butyl ether (MTBE), are also detected by a photoionization detector, as well as olefins, branched alkanes, and cycloalkanes. 

On the other hand, the complex mixture of petroleum hydrocarbons potentially present in an air sample can be minimized by separation of the sample into aliphatic and aromatic fractions, and then these two major fractions are separated into smaller fractions based on carbon number. Individual compounds (e.g., benzene, toluene, ethylbenzene, xylenes, MTBE, naphthalene) are also identified using this method. The range of compounds that can be identified includes C4 (1,3-butadiene) through C12 (n-dodecane). 

It is not surprising that the data produced as total petroleum hydrocarbons (EPA 418.1) suffer from several shortcomings as an index of potential ground-water contamination or health risk. In fact, it does not actually measure the total petroleum hydrocarbons in the sample but rather, measures a specific range of hydrocarbon compounds. This is caused by limitations of the extraction process (solvents used and the concentration steps) and the reference standards used for instrumental analysis. The method specifically states that it does not accurately measure the lighter fractions of gasoline [benzene-toluene-ethylbenzene-xylenes fraction (BTEX)], which should include the benzene-toluene-ethylbenzene-xylenes fraction. Further, the method was originally a method for water samples that has been modified for solids, and it is subject to bias. 

The Vaportech technology has been used in the past to treat soils contaminated with chlorinated solvents such as perchloroethylene (PERC) and trichloroethylene (TCE) benzene, toluene, ethylbenzene, xylenes (BTEX) aromatics, ketones, gasoline-range and diesel-range organics, phenols, and other cyclic and noncyclic carbon compounds including ketones, naphtha, mineral spirits, and lacquer diluter. 

The technology can potentially treat the following contaminants halogenated volatiles and semivolatiles, nonhalogenated volatiles and semivolatiles (also listed as actual), organic pes-ticides/herbicides, polynuclear aromatic compounds (PNAs), solvents, and benzene-toluene-ethylbenzene-xylene (BTEX). 

PerkinElmer, Inc. (formerly EG G, Inc.), reports that NoVOCs installations have treated sites contaminated with benzene, toluene, ethylbenzene, xylene, trichloroethene (TCE), tetra-chloroethene (PCE), and petroleum hydrocarbons. The technology is unlike conventional pump-and-treat technologies in that it avoids the necessity of pumping water above ground for... 

This increases the number of advective airflow paths and the volume of soil in contact with advective airflow. According to the vendor, the PSF technology used in conjunction with Terra Vac s Dual Vapor Extraction has successfully remediated benzene, toluene, ethylbenzene, xylene, (BTEX), tetrachloroethylene (PCE), trichloroethylene (TCE), dichloroethylene (DCE), trichloroethane (TCA), dichlorobenzene, trichloropropane, and gasoline. 

ESTD, ex situ thermal desorption VOCs, volatile organic compounds TPH, total petroleum hydrocarbons BTEX, benzene, toluene, ethylbenzene, xylene PCBs, polychlorinated biphenyls PAHs, polycyclic aromatic hydrocarbons ISTD, in situ thermal desorption. 

Photocopiers Benzene, toluene, ethylbenzene, xylene, styrene 18,19, 20... 

Among the kinetic sampling devices, ceramic dosimeters have been used successfully for the long-term surveillance of VOCs.92 They use a ceramic tube as the diffusion-limiting barrier that encloses a receiving phase consisting of solid sorbent beads. Over a three-month deployment in a contaminated aquifer, the ceramic dosimeter provided TWA concentrations of benzene, toluene, ethylbenzenes, xylenes, and naphthalenes. The levels obtained matched closely those found in spot water samples that were taken frequently over the trial period.54... 

Among the volatile fuel hydrocarbons, benzene, a known carcinogen is of utmost concern from a human-health perspective. Alkenes and alkylben-zenes are considered more toxic than alkanes (Oestermark and Petersson, 1993). All alkenes are potentially genotoxic because of metabolic formation of epoxides (Oestermark and Petersson, 1993). Of particular concern are ethene and 1,3-butadiene. Although alkanes are considered less toxic, in general, than alkenes or alkylbenzenes, hexane is a known neurotoxin (Perbellini et al., 1980). Calabrese and Kenyon (1991) report on the toxicological assessment of numerous volatile hydrocarbons including benzene, toluene, ethylbenzene, xylenes, and n-hexane. 

Abbreviations 2,4,-D 2,4-dichlorophenoxyacetic acid 2,4,5-T tiichlorophenoxyacetic acid BTEX benzene, toluene, ethylbenzene, xylenes PAH polycyclic aromatic hydrocarbons. 

The vast amount of data from natural attenuation studies of petroleum hydrocarbon plumes generally supports anaerobic degradation, especially for benzene, toluene, ethylbenzene, xylenes (BTEX) under field conditions. The first-order degradation rates observed under unspecified anaerobic conditions (Suarez and Rifai, 1999) are typically one or two orders of magnitude lower than rates reported under aerobic conditions (Nielsen et al, 1996). 

Some simple examples help illustrate this point. A study by Burris and MacIntyre (1984) compared the theoretical solubilities of specific chemicals in water to the solubilities of the same chemicals when they were part of such petroleum product mixtures as JP-4 jet fuel. The results are summarized in Table 5-8. Similar comparisons for all the BTEX (benzene, toluene, ethylbenzene, xylene) chemicals, based on materials presented by Potter (1993), are presented in Table 5-9. 

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