Volatile organic carbon compounds

The commercialization by Kureha Chemical Co. of Japan of a new, highly attrition-resistant, activated-carbon adsorbent as Beaded Activated Carbon (BAC) allowed development of a process employing fluidized-bed adsorption and moving-bed desorption for removal of volatile organic carbon compounds from air. The process has been marketed as GASTAK in Japan and as PURASIV HR (91) in the United States, and is now marketed as SOLD ACS by Daikin Industries, Ltd. 

Rudolph, J., Biogenic Sources of Atmospheric Alkenes and Acetylene, in Biogenic Volatile Organic Carbon Compounds in the Atmosphere (G. Helas, J. Slanina, and R. Steinbrecher, Eds.), pp. 53-65, SPB Academic Publishing, Amsterdam, f997. 

A 10—30 xL sample is then injected into the instrument. Initially, the water and any volatile organic carbon compounds present are vaporized at 200°C. The volatilized carbon compounds are first completely oxidized to carbon dioxide, and then all the carbon dioxide is catalytically converted to methane, in a hydrogen atmosphere (Eq. 4.41). 

CFC-ll, chlorofluorocarbon 1,4DCB, 1,4-dichlorobenzene NMVOC, nonmethane volatile organic carbon compound PM, particulate matters DALY, dis- ... 

Finally, there are also pollutants that do not cause direct health impacts hut that may have the potential to cause harm indirectly, through their actions on the overall ecology, or as they function as precursor chemicals that lead to the production of other harmful chemicals. The major indirect-action pollutants include volatile organic carbon (VOC) compounds that act as precursors to more harmful species chemicals called halocarbons and chemicals called greenhouse gases. 

As for all of the fractions of organic material in seawater, the volatile organic carbon fraction is defined by the method by which it is collected. In one of the earliest estimates, Skopintsev [93] defined the volatile fraction as the difference between total organic carbon values, as measured by evaporation and dry combustion, when the evaporations were carried out at room temperature and at 60 °C. Thus Skopintsev s volatile fraction consists of those compounds that are volatile from acidified solution taken to dryness at 60 °C but not at 20 °C. This fraction was found to be between 10 and 15% of the total organic carbon. He also noted a 15% difference in measured organic carbon with his dry combustion method when samples were dried at different temperatures and concluded that this difference was due to the loss of volatiles. 

Hewitt found that volatile organic compounds are readily lost from soil samples unless care is taken to limit surface area exposure and to ensure subsample isolation [338]. Volatile organic carbon losses were found to be most abundant during field collection and storage. Hewitt reported that fortified soils held in sealed glass ampoules at 4 °C, or dispersed in methanol and held at 22 °C, showed no significant losses over 20 and 98 days, respectively [339]. 

Kawata et al. [ 128] have described the effects of headspace conditions on recoveries of volatile organic compounds from sediments and soils. Hewitt [129] compared three vapour partitioning headspace and three solvent extraction methods for the preparation of soil samples for volatile organic carbon determination in soils. Methanol extraction was the most efficient method of spiked volatile organic carbon recovery, which depended on the soil organic carbon content, the octanol-water partitioning coefficients of analytes and the extraction time. 

Volatile organic carbon VOC filter Low boiling (<100°C), low-molecular-weight compounds... 

Such an approach has been used to develop customized noses (specific arrays of polymers) for classification of beers, detection and identification of microorganisms, olive oil characterization, and detection/classification of BTEX compounds (volatile organic carbons). 

Trace amounts of organic carbon compounds in water can also be determined by this technique (99). The sample is heated in a nitrogen carrier gas in two stages to determine volatile (150°C) and nonvolatile (150-550°Q organic carbon. The water evaporated in the first stage changes the detector response... 

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