Volatile organic compounds possible sources

Formaldehyde is one of several volatile organic compounds. Indoor sources of formaldehyde include particleboard, plywood, fibre board, panelling, urea formaldehyde foam insulation and some carpets and furniture, as well as some household chemicals. Formaldehyde is a well-known irritant of the upper respiratory tract. Other problems may include IgE sensitisation to formaldehyde, and the possibility that formaldehyde exposure increases the risk of IgE sensitisation to common aeroallergens. In a study in Australia it was shown that low-level exposure to indoor formaldehyde may increase the risk of IgE sensitisation to common aeroallergens in school children [311(111)]. 

Table 5 Possible sources of the most prevalent volatile organic compounds found in audited buildings as found in a literature survey [50]... 

Abstract The possible utilization of room temperature ionic liquids (RTILs), instead of volatile organic compounds (VOCs), in the electrochemical procedures of organic synthesis has been discussed. The synthesis of p-lactams, the activation of carbon dioxide and its utilization as renewable carbon source and the carbon-carbon bond formation reactions via umpolung of aldehydes (benzoin condensation and Stetter reaction) and via Henry reaction have been selected as typical electrochani-cal methodologies. The results, related to procedures performed in RTILs, have been compared with those performed in VOCs. The double role of RTILs, as green solvents and parents of electrogenerated reactive intermediates or catalysts, has been emphasized. 

Chapter 16 outlines the possible utihzation of room-temperature ionic liquids (RTILs), instead of volatile organic compounds (VOCs), in the electrochemical procedures of organic synthesis of alpha- and beta-lactams. The activation of carbon dioxide and its utilization as a renewable carbon source is also highlighted. 

Abstract In the last decade, it became increasingly evident that the fuel oxygenate methyl tertiary butyl ether (MTBE) is nearly ubiquitous in the worldwide environment. The detection frequency of MTBE rivals other volatile organic compounds (VOCs) that have been produced and used for a much longer period of time. Its mere presence in water bodies used as drinking water reservoirs (rivers, lakes, or groundwater tables) has aroused concern about its potential sources, persistence, or possible adverse effects (aesthetic or toxic implications) for end-users and aquatic life. The purpose of this chapter is to provide an updated overview of the current environmental concentrations, the occurrence of the pollutant in the different aquatic compartments, the relevance of diffuse and point sources, and the different alternatives for remediation of MTBE contaminated sites. 

In recent years, ionic liquids have emerged as possible "green solvents", that is environmentally benign substances mainly because they have negligible vapor pressure (Liu et al., 2005). One of the primary driving forces behind research into ionic liquids is the perceived benefit of substituting traditional industrial solvents, most of which are volatile organic compounds (VOCs), with nonvolatile ionic liquids. Replacement of conventional solvents by ionic liquids would prevent the emission of VOCs, a major source of environmental pollution (Polshettiwar Varma, 2008). 

The most straightforward tool for the introduction of a sample into a mass spectrometer is called the direct inlet system. It consists of a metal probe (sample rod) with a heater on its tip. The sample is inserted into a cmcible made of glass, metal, or silica, which is secured at the heated tip. The probe is introduced into the ion source through a vacuum lock. Since the pressure in the ion source is 10-5 to 10-6 torr, while the sample may be heated up to 400°C, quite a lot of organic compounds may be vaporized and analyzed. Very often there is no need to heat the sample, as the vapor pressure of an analyte in a vacuum is sufficient to record a reasonable mass spectrum. If an analyte is too volatile the cmcible may be cooled rather than heated. There are two main disadvantages of this system. If a sample contains more than one compound with close volatilities, the recorded spectrum will be a superposition of spectra of individual compounds. This phenomenon may significantly complicate the identification (both manual and computerized). Another drawback deals with the possibility of introducing too much sample. This may lead to a drop in pressure, ion-molecule reactions, poor quality of spectra, and source contamination. 

The observed ambient organic aerosol formation rates are also consistent with those estimated by extrapolation of smog-chamber kinetic data. Other heavy unsaturates, such as styrene and indene, are present in the atmosphere and may contribute, in part, to the formation of benzoic acid and homophthalic acid, respectively. Diesel exhaust and industrial emission are possible sources of such heavy unsaturates. Diolefins of C6+ are not present in gasolines and exhaust gases and have not been found in the atmosphere, and their possible role as precursors of the Cs-7 difiinctional acidic compounds is seriously challenged. Lower diolefins are emitted in automobile exhaust. Examination of vapor-pressure data indicates that the bulk of their expected photooxidation products remains in the gas phase, including most of the less volatile C3-4 dicarboxylic acids. 

The biologically mediated emission of Po from a culture solution insulated with a sea sediment extract was observed. The emitted Po compound was considered to be lipophilic because it collected in organic solvents. Microorganisms are responsible for the emission of volatile Po compounds because no volatile compounds of Po were formed in a sterile medium. There exists an argument for the existence of a biotic source for atmospheric Po in the environment, which possibly originates from abiotic sources. The emission behavior of both Po and S in the culture experiments was compared. The chemical form of the emitted Po is not known, but it was emitted with dimethyl sulfide. A volatile Po compound was formed when methylcobalamin was used in the experiments. 

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