Total volatile organic carbon

It is important to identify volatile organic carbon (VOC) and the presence of specific priority poUutants, ia additioa to the total organic content. The... 

Note TRS, total reduced sulfur VOC, volatile organic carbon F, fluorides. 

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. 

Table 11.3. Averaged volatile organic carbon (VOC) concentrations and VOC total organic carbon (VOC TOC) ratios from different areas [92]...

Table 11.3 presents some typical results obtained by this procedure on seawater samples. MacKinnon [92] concluded that since the volatile organic carbon contents of normal (i.e., unpolluted) seawaters are small, the effect of complete or partial loss of volatile organic components during the determination of total organic carbon in most ocean areas (except highly reducing environments) with either the wet and direct injection methods or dry oxidation methods should be small (about 5%), and within the precision of these methods. 

Several patents discuss the use of Raman spectroscopy to determine the properties of finished products.93 94 For reformulated gasoline, some of these properties include sulfur, olefin, benzene, volatile organic carbon (VOC), nitrogen oxides (NOx), aromatic contents, total air pollutants (TAPs), Reid Vapor Pressure (RVP), distillation properties, motor and research octane numbers, and drivability. For the octane numbers, the accuracy of the Raman method was limited by errors in the reference method. 

Environmental criteria have been established for many of these, but the utility and applicability of such criteria for indoor environments is controversial for at least four reasons. Eor example, the goals of the threshold limit values often do not include preventing irritation, a primary concern in indoor environments with requirements for close eye work at video display terminals. For most of the pollutant categories, the problem of interactions, commonly termed the multiple contaminants problem , remains inadequately defined. Even for agents that are thought to affect the same receptor, such as aldehydes, alcohols, and ketones, no prediction models are well established. Finally, the definition of representative compounds for measurement is unclear. That is, pollutants must be measurable, but complex mixtures vary in their composition. It is unclear whether the chronic residual odor annoyance from environmental tobacco smoke correlates better with nicotine, particulates, carbon monoxide, or other pollutants. The measure total volatile organic compounds is meanwhile... 

Fig. 5. Depth-averaged profiles of volatile organic carbon (VOC) concentrations and its fraction of total organic carbon (VOC/TOC) measured in various geographic areas. Bars represent range of values measured = VOC O = VOC/TOC. A. Gulf of St. Lawrence. B. Nova Scotian shelf and slope. C. Sargasso Sea.

Stoddard solvent may be released to the atmosphere in the exhaust emissions of dry cleaning plants. Emissions from one plant were determined to be 2,100 ppm (measured as propane) (EPA 1980). Fugitive emissions from other industrial or domestic uses (such as incompletely sealed or punctured barrels) may contribute to levels of Stoddard solvent in the environment, including contributions to general levels of volatile organic carbon. In addition, surface water contamination may occur as a result of direct spills of Stoddard solvent onto surface waters, runoff from spills to soil with subsequent transmission to nearby water sources, or from improper disposal, such as pouring Stoddard solvent down drains. Accidental spills of Stoddard solvent to various media are reported to the Emergency Response Notification System (ERNS) maintained by EPA. Total spill data for Stoddard solvent are ... 

In two experiments shown in Figure III. sodium carbonate concentrations of 0.07 and 0.30 N resulted in roughly the same total volatile organic material concentration in the aqueous phase of the product. There are some differences in relative product concentrations, but the overall GC traces are very similar. Actual identity of each component will be confirmed by GC/MS but is irrelevant here. In Figure IV. a GC trace at an alkali concentration of 0.60 N but with a reaction time of 6 hr gave a very similar product distribution to that observed after 3.5 hr (Figure III). However, a zero alkali concentration (Figure IVa) resulted in only traces of product under the same conditions. 

Potable Water Treatment. Treatment of drinking water accounts for about 24% of the total activated carbon used in Hquid-phase apphcations (74). Rivers, lakes, and groundwater from weUs, the most common drinking water sources, are often contaminated with bacteria, vimses, natural vegetation decay products, halogenated materials, and volatile organic compounds. Normal water disinfection and filtration treatment steps remove or destroy the bulk of these materials (75). However, treatment by activated carbon is an important additional step in many plants to remove toxic and other organic materials (76—78) for safety and palatability. 

Human-made sources cover a wide spectrum of chemical and physical activities and are the major contributors to urban air pollution. Air pollutants in the United States pour out from over 10 million vehicles, the refuse of over 250 million people, the generation of billions of kilowatts of electricity, and the production of innumerable products demanded by eveiyday living. Hundreds of millions of tons of air pollutants are generated annu ly in the United States alone. The five main classes of pollutants are particulates, sulfur dioxide, nitrogen oxides, volatile organic compounds, and carbon monoxide. Total emissions in the United States are summarized by source categoiy for the year 1993 in Table 25-10. 

When granular activated carbons (GAC) are used as the filter media, the GAC filter can also remove dissolved organics (such as TTO, total toxic organics or VOC, volatile organic compounds).1011... 

COD, chemical oxygen demand TKN, total Kjeldahl nitrogen TSS, total suspended solids VSS, volatile suspended solids TOC, total organic carbon. 

MacKinnon MD (1977) The analysis of the total organic carbon in seawater a. Development of methods for the quantification of TOC b. Measurement and examination of the volatile fraction of the TOC. PhD Dissertation. Dalhousie University... 

The loss of volatile organics will only be a problem in areas where the volatile component is high. In open ocean areas volatiles should be a small fraction (2-6%) of the total organic carbon [91]. Under strongly reducing conditions,... 

In further work to that discussed above, MacKinnon [183] has discussed in detail a method for the measurement of the volatile fraction of total organic carbon in seawater. 

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