Study Of Volatile Organic Compounds Research Articles

Sorption studies of volatile organic compounds in a divinyl‐terminated poly(dimethylsiloxane)–oligo polymer

AbstractThe sorption equilibria and kinetics of three volatile organic compounds (VOCs)—benzene, chloroform, and acetone—in a newly developed divinyl‐terminated poly(dimethylsiloxane) (PDMSvi)–oligo polymer were studied. The PDMSvi–oligo polymer was prepared from a hexane solution consisting of PDMSvi as the polymer, oligosilylstyrene as the crosslinker, and a platinum–divinyltetramethyldisiloxane complex as the Karstedt catalyst. The sorption uptake of each VOC by the polymer was measured gravimetrically at different VOC partial pressures at a constant temperature and at different temperatures between 24 and 50°C. The rate of VOC sorption was monitored until equilibrium was established. The solubility coefficient increased when the VOC activity increased, and the results revealed that the PDMSvi–oligo polymer was a good sorbent for the three VOCs examined. Relatively high solubilities of these VOCs were obtained in this polymer in comparison with those reported for conventional silicone rubbers. The Flory–Huggins model fit the observed equilibrium sorption isotherms of the benzene and chloroform systems very well, whereas the Koningsveld–Kleinjtens variation law had to be combined with the Flory–Huggins model to describe the sorption isotherm of acetone in the polymer film. The rates of sorption of the three VOCs in the polymer samples were generally rapid and controlled by Fickian diffusion. The diffusivities of benzene, chloroform, and acetone at 24°C, determined with the diffusion equation, were approximately 10−6 cm/s. The sorption and diffusion data revealed that the newly developed PDMSvi–oligo polymer was an excellent sorbent for the three VOCs examined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 920–927, 2004

SPME applied to the study of volatile organic compounds emitted by three species of Eucalyptus in situ. Solid-phase micro extraction.

Headspace solid-phase microextraction coupled to gas chromatography/ion trap mass spectrometry-65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) was used to identify and monitor the emission patterns of biogenic volatile organic compounds from leaves of Eucalyptus dunnii, Eucalyptus saligna, and Eucalyptus citriodora in situ. Short extractions (1 min) were performed every 30 min for periods of 8-10 h during 24 days taking advantage of the high capacity of this porous polymer coating. Forty-two compounds were detected and 20 identified in the headspace of E. saligna leaves, and 19 of 27 compounds were identified in the headspace of E. dunnii leaves. The emission pattern of (E)-beta-ocimene and rose oxide suggests that they may play a bioactive role in Eucalyptus.

Actual commuter exposure to methyl-tertiary butyl ether, benzene and toluene while traveling in Korean urban areas

This study evaluated in-car and in-bus exposures to methyl-tertiary butyl ether (MTBE), benzene, and toluene on actual commuting routes, not hypothetical routes as used in many previous in-vehicle exposure studies of volatile organic compounds (VOCs). It focuses on four potentially influencing factors (transportation mode, passenger-car type, time of day, and season). A total of 40 passenger car commuters and 20 public bus commuters were recruited. The same commuters participated in both the summer and winter studies. The transportation mode, passenger-car type and commute season were all found to affect the in-vehicle levels of the target VOCs. Conversely, the commute time of day had little effect on the in-car and in-bus levels of the target compounds. The present study also confirmed that under Korean commuting conditions, passenger car and public bus interiors are important microenvironments for exposure to MTBE, benzene and toluene. This is supported by a previous finding that both in-car and in-bus air levels of the target VOCs tend to be much higher than ambient air levels of the compounds. Meanwhile, some spurious gasoline sold during the experimental periods appears to have elevated the in-car and in-bus exposures to toluene compared with those reported by some previous studies conducted in the same study area.

Use of a Dynamic Headspace GC-MS Method for the Study of Volatile Organic Compounds in Polyethylene Packaging. An Undergraduate Experiment in Polymer Analysis

A novel experiment is described for introducing senior undergraduate physical chemistry and food science students to a technique commonly used to identify volatile organic compounds (VOCs) that are emitted from polymers at ambient temperatures. The VOCs in food-grade low-density polyethylene (LDPE) pellets are purged with nitrogen and trapped at ambient temperature on a Tenax-GC (2,6-diphenyl-p-phenylene oxide polymer) sorbent. The VOCs are liberated using dynamic headspace desorption and are separated and identified using the technique of gas chromatography-mass spectrometry (GC-MS). The relationship between the chromatographic peak area of a given VOC and the temperature of desorption, as well as the relationship between the total chromatographic area and the temperature of desorption, are quantitatively modeled using a modified form of the van't Hoff isochore.

室内及び屋外の揮発性有機化合物の北九州市における分布の実態（Ｉ）

発がん関連物質を含む15種のVOCs (ハロゲン化炭化水素9種, 芳香族炭化水素5種, その他1種) の濃度の経時変化を北九州市内の5戸の住宅で調査した。試料空気はグラファイトカーボン吸着剤 (Carbopack B) とカーボンモレキュラーシープ吸着剤 (Carbosieve S II) を充てんした捕集管をオートサンプラーに装着して, 室内と屋外の空気を同時に採取した。採取した試料を加熱脱着し, GC/MS-SIMで各濃度を測定した。その結果, 室内空気で比較的時間変動が大きかった化合物はクロロホルム, 1, 1, 1-トリクロロエタンであったが, p-ジクロロベンゼンとα-ピネンは小さな変動を示した。室内空気で最も高いリスクを与えたのはp-ジクロロベンゼン (1.7×10-5) であった。また, 10物質の経気道暴露による損失寿命を計算すると室内空気で170分となった。

A Versatile Gas Uptake Inhalation System Used in Pharmacokinetic and Metabolic Studies of Volatile Organic Compounds

This paper describes an automated gas uptake system for pharmacokinetic research with volatile organic compounds, designed to operate within the parameters maintained during conventional whole-body inhalation exposures according to the Good Laboratory Practices (GLP) guidelines. Benefits are twofold: (1) to ensure that animals are tested under the same widely accepted guidelines, and (2) to minimize the number of animals required to perform a study, by allowing direct comparison of results from gas uptake studies with results from other inhalation toxicology studies and use of animals from gas uptake experiments for postexposure toxicological testing. Other features implemented in the chamber design improve the ease of use and productivity of the system. These include provisions to adapt the apparatus for use in different pharmacokinetic experimental protocols, automation of data acquisition and oxygen control during exposures, and automated calculation of exposure summary statistics and graphics using a spreadsheet program. The automation system reduces the labor hours required to perform a gas uptake experiment by approximately one-half.

Source-receptor study of volatile organic compounds and particulate matter in the Kanawha Valley, WV—II. Analysis of factors contributing to VOC and particle exposures

The Kanawha Valley region of West Virginia includes a deep river valley with a large population living in close proximity to many potential sources of ambient volatile organic compounds (VOCs). The valley runs approximately 100 km from Alloy to Nitro and is between 100 and 200 m deep. Nearly 250,000 people live in this section of the valley, which includes the state capital of Charleston. Many large chemical manufacturing, transportation, and storage facilities are also located within the valley's walls. The topography, population density, and locations of sources dictate the possibility of high population exposures. To investigate exposures to VOCs emitted by the local industry, simultaneous measurements of 19 VOCs, particle pH, particle elemental composition, inorganic gases, and meteorological parameters were collected over an entire year. With the use of a mobile van, sampling was performed in the valley at three sites. Samples were collected for 15 days per month for 4 months at each site. Both unvariate and multivariate analyses were performed in an effort to resolve source contributions. Results of factor analyses suggest auto-related, transported aerosol, chlorinated organic sources as well as site-specific sources and a single incident source—a forest fire. The techniques employed suggest that inclusion of VOC measurements increase the ability of such studies to identify pollutant sources.

Source-receptor study of volatile organic compounds and particulate matter in the Kanawha Valley, WV—I. Methods and descriptive statistics

The Kanawha Valley of West Virginia is a highly industrialized region stretching 100 km from Alloy in the southeast to Nitro in the north. The valley which contains the state capital, Charleston, has a population of approximately 250,000 and is noted for its chemical manufacturing industry. The valley itself is narrow and steeply-walled. The combination of topography, local meteorological conditions, and the chemical industry potentiate elevated concentrations of volatile organic compounds (VOC) emitted within the region. An integrated approach designed to assess pollutant exposure in this region was implemented between April 1987 and March 1988. Data were collected simultaneously on volatile organic compound concentrations, particle pH, inorganic gases, and meteorological parameters. Data were collected using a mobile van sampling platform at one of the three within-valley sites for 15 days each month. A discussion of sampling methodology and statistics describing pollutant concentrations are presented in this paper. Concentrations of most pollutants were found to be in agreement with those found by other researchers, except during a period when a forest fire influenced the air quality. The results suggest that multivariate relationships may be found that will be useful in source identification.

Analysis of volatile organic compounds in polymers by dynamic headspace—multi-dimensional gas chromatography —mass spectrometry

The use of dynamic headspace—multi-dimensional gas chromatography—mass spectrometry in studies of volatile organic compounds in plastics is described. The results demonstrate the utility of this technique to increase the resolution of selected compounds, to generate less overlapped mass spectra and to obtain a higher confidence of the analysis results. Some construction features of the laboratory-assembled system are discussed.

Concentrations of selected organic pollutants in indoor and outdoor air in Northern Italy

This paper reports on an observational study of volatile organic compounds (VOC) in the air of 14 homes and one small office building. The study consists of two parts: (a) 4–7 days mean values of the concentrations of 35 selected VOC have been determined together with some complementary parameters in indoor and outdoor air in order to get an indication of the relative importance of indoor air pollution by VOC in this geographical area; (b) six indoor air samples have been analysed in detail by GC-MS for a more complete qualitative characterization of indoor air pollution by VOC. Major results are: concentrations of the 35 selected VOC were nearly always higher indoors than outdoors, often by an order of magnitude. The mean concentration of total volatile organic compounds was about 3 mg/m 3 indoors compared to 0.4 mg/m 3 outdoors. Detailed GC-MS analysis leads to the identification of a much larger number of compounds (more than 100 in two cases). Most of the identified compounds are solvent constituents and many of them have also been detected in northern Europe and in the United States. This points to common use consumer products as major sources rather than to building materials, which differ between geographical areas.