Compounds In Vapor Phase Research Articles

A source study of atmospheric polycyclic aromatic hydrocarbons in Shenzhen, South China

Air pollution has become a serious problem in the Pearl River Delta, South China, particularly in winter due to the local micrometeorology. In this study, atmospheric polycyclic aromatic hydrocarbons (PAHs) were monitored weekly in Shenzhen during the winter of 2006. Results indicated that the detected PAHs were mainly of vapor phase compounds with phenanthrene dominant. The average vapor phase and particle phase PAHs concentration in Shenzhen was 101.3 and 26.7 ng m( - 3), respectively. Meteorological conditions showed great effect on PAH concentrations. The higher PAHs concentrations observed during haze episode might result from the accumulation of pollutants under decreased boundary layer, slower wind speed, and long-term dryness conditions. The sources of PAHs in the air were estimated by principal component analysis in combination with diagnostic ratios. Vehicle exhaust was the major PAHs source in Shenzhen, accounting for 50.0% of the total PAHs emissions, whereas coal combustion and solid waste incineration contributed to 29.4% and 20.6% of the total PAHs concentration, respectively. The results clearly indicated that the increasing solid waste incinerators have become a new important PAHs source in this region.

The effect of carbon pore structure on the adsorption of cigarette smoke vapour phase compounds

The pore size, distribution and volume of activated carbon are extremely important for maximizing adsorption of vapours formed during cigarette smoking. Increasing micropore volume leads to an increase in the removal efficiency. Because of the relatively high flow rates encountered during the smoking process, mesopores appear to be beneficial as transport pores especially in cases where the micropore volume is relatively low and thus the most accessible micropore sites may be rapidly saturated. Film diffusion limitations seem to be present at the very high space velocities encountered in a filter under the conditions of cigarette smoking. The removal efficiency from smoke is approximately inversely proportional to the vapour pressure of the constituents.

Fabrication of Yb-doped silica glass through the modification of MCVD process

A method to deliver Yb and Al compounds in vapor phase to the reaction/deposition zone has been devised for modified chemical vapor deposition (MCVD) process. By using this MCVD setup, we succeeded to prepare silica glass preforms presenting uniform dopants concentrations in the radial and longitudinal directions with good reproducibility. Preforms with a core diameter larger than 5 mm were easily prepared by depositing around 40 layers. By changing some parameters in the deposition step, such as carrier gases flow and temperatures of Yb(DPM) 3 and AlCl 3 furnaces, different concentrations of Yb and Al were incorporated into the core region of the silica glass preforms. By adjusting the Yb and Al concentrations, we succeeded to prepare preforms for large mode area (LMA) fiber with a change less than 10% of nominal refractive index.

The effect of the pore size and volume of activated carbon on adsorption efficiency of vapor phase compounds in cigarette smoke

Adsorption of volatile organic compounds (VOCs) in cigarette smoke by activated carbons was measured to investigate the correlation between the adsorption efficiencies of the VOCs and pore size and volume of the activated carbons. The adsorption efficiency E is defined by E = ( C i,in – C i,out )/ C i,in where C i,in and C i,out are the concentration of the ith VOC component in cigarette smoke before and after adsorption, respectively. E relates to a weight of activated carbons w which is described by a logarithmic penetration equation, ln(1 − E) = − Kw ( K: constant). The value of K for one smoke constituent increased linearly with the adsorption capacity determined by DR plot, W 0. K was well predicted by the value of the slope, D, of DR plot as K = ( a 1 D 2 + a 2 D + a 3) W 0, ( a 1, a 2, a 3: constants), and this equation can be applicable to various smoke constituents by substituting the affinity coefficient ( β) of a given adsorbate included in D. Thus, the adsorption efficiency of various smoke constituents for a particular activated carbon is predicted by analyzing W 0 and D for an adsorbate in cigarette smoke.

POLYCYCLIC AROMATIC HYDROCARBONS OF DIESEL AND GASOLINE EXHAUST AND DNA ADDUCT DETECTION IN CALF THYMUS DNA AND LYMPHOCYTE DNA OF WORKERS EXPOSED TO DIESEL EXHAUST

Particles present in urban air pollution are mainly derived from diesel- and gasoline-fueled vehicles. Exhaust emission is able to cause several health effects in humans including mutagenicity and carcinogenicity. Polycyclic aromatic hydrocarbons (PAHs) were measured in diesel and gasoline particulate extracts and DNA binding to CT DNA (±S9 and ±XO) was investigated. A large difference in content of 14 PAHs in diesel and gasoline extracts was observed, showing higher concentration of 14 PAHs, 6 carcinogenic PAHs, benzo[a]pyrene (B[a]P) in diesel than in gasoline extracts. Selected PAH standards of B[a]P, benzo[c]fluoranthene (B[c]F), and 3-nitrobenzanthrone (NBA) were used in 32P-postlabeling/polyacrylamide gel electrophoresis (PAGE) technique to identify CT DNA adducts formed by diesel particulate extracts. CT DNA adduct formation was higher for diesel extracts in comparison with gasoline extracts; however, no clear origin of DNA adducts derived from B[c]F-, 3-NBA-, B[a]P was detected. 32P-postlabeling/PAGE was a useful assay for analyzing and identifying PAH-DNA adducts. Occupational exposure to particulate and volatile PAH concentrations were evaluated using personal air samples and lymphocyte DNA adducts as markers of exposure. Overall air PAH concentrations were low in all eight workplaces, consisting of 97% of vapor phase compounds. DNA adducts analyzed by 32P-postlabeling assay were compared between the butanol and nuclease P1 enrichment procedures. Only in winter samples of exposed workers, butanol extraction revealed significantly higher adduct levels in comparison with those of control persons. No differences in adduct levels between exposed and control persons in summer were detected by using either butanol extraction or nuclease P1 treatment. Total concentrations of particulate and volatile PAHs measured in eight workplaces in winter showed a significant correlation with total DNA adducts analyzed in workers' lymphocytes (r = 0.852N = 8, p = .007).

Analysis of particle and vapour phase PAHs from the personal air samples of bus garage workers exposed to diesel exhaust.

The levels of particle and vapour phase polycyclic aromatic hydrocarbons (PAHs) derived from the diesel exhaust compounds in bus garage work were measured in winter and in summer. Five personal air samples were collected from the breathing zones of 22 garage workers every other day of consecutive weeks. Control samples (n = 22) were collected from office workers in Helsinki. Fifteen PAHs in the air samples were analysed by HPLC using a fluorescence detector. Statistically significant differences were observed between total PAH levels of the exposed workers (2241 and 1245 ng/m(3)) and the control group (254 and 275 ng/m(3)) in both winter (P < 0.001) and summer (P < 0.001). Phenanthrene, pyrene, benzo[ghi]perylene and fluoranthene were the major compounds in the particle phase, and naphthalene, phenanthrene and fluorene in the vapour phase. About 98% of PAHs measured were related to the vapour phase compounds, whereas the high molecular weight PAH compounds were detected only in the particle phase. The PAH levels in the garages were twice as high (P < 0.001) in winter as in summer. Even though the exposure levels were low in the bus garages, the low level does not allow conclusions to be drawn about the possible adverse health effects due to exposure to diesel exhaust.

Thermodynamic study of the behavior of uranium and plutonium during thermal treatment under reducing and oxidizing modes

This study investigated the equilibrium compositions of uranium and plutonium under various thermal treatment conditions using an incineration equilibrium calculation program. The treatment conditions examined included temperature, oxygen level (either reducing or oxidizing), and the existence of chlorine. In a simulation, a selected waste containing either uranium or plutonium was input to the program along with the desired treatment conditions. The program then performed the free energy calculations and searched for the optimum composition which minimizes the total system free energy. The simulation results have indicated that, under a reducing mode, uranium tends to stay in a solid phase as UO 2(s) up to 1500°C; however, under an oxidizing mode, it will exist as U 3O 8(s) up to 1100°C. As the temperature increases, the solid-phase compounds either vaporize or decompose into various vapor-phase compounds. Under a reducing mode, all the preferred compounds will be in vapor phase when the system temperature is above 1900°C; under an oxidizing mode, this temperature is 1450°C. For plutonium, the thermodynamically preferred solid-phase compound is PuO 2(s) up to about 1500°C under either a reducing or an oxidizing mode. As the temperature increases, the compound will vaporize mainly into its vapor phase, i.e. PuO 2(g), up to about 2000°C. Above this temperature, the system contains only vapor-phase compounds. In addition to equilibrium composition, the effective vapor pressure and the fraction in vapor phase for the two metals have also been evaluated. The existence of chlorine has not been found to affect the simulation results significantly. The simulation results have been compared with those generated from the HSC program and the results have indicated that the HSC program contains inappropriate thermodynamic data for uranium and plutonium simulations.

Integrated supercritical fluid extraction, bioassay and chemical screening methods for analyzing vapor-phase compounds of an environmental complex mixture: Diesel exhaust

The integration of bioassay and chemical analyses for vapor-phase compounds in environmental complex mixtures is a challenging process due to the volatility and the limited amounts of compounds collected and subsequently assayed. The advantage of an integrated approach is that the bioassay could aid in determining the most biologically active fractions for further chemical analyses. Previously, we reported on the use of supercritical fluid extraction (SFE) in conjunction with a Salmonella microsuspension assay to measure mutagenic activity in model vapor-phase mutagens. The procedure was effective in minimizing losses of the vapor-phase samples. In the present study, we performed the bioassay and chemical characterization of the vapor-phase mutagens using the exhaust from a medium heavy-duty diesel truck as a model complex mixture. Compounds present in undiluted diesel exhaust were trapped using a sampling train consisting of a Teflon filter, polyurethane foam (PUF) and XAD-4 (XAD), in series. Compounds in the PUF and XAD samples were extracted by SFE using supercritical carbon dioxide, and fractions were collected based on increasing pressures. For the bioassay, the Salmonella microsuspension assay was used throughout with tester strains TA98 and TAIOO, with and without the addition of metabolic enzymes (± S9). The two most mutagenic fractions from PUF were further fractionated using high performance liquid chromatography (HPLC). Chemical analyses of the HPLC fractions were by gas chromatography with a mass selective detector (GC/MS). Compounds present in these PUF SFE fractions included substituted naphthalenes, biphenyls, fluorenes, dibenzothiophenes and phenanthrenes or anthracenes. Compounds present in the XAD SFE fractions included substituted benzenes and naphthalenes, alkyl naphthalenes, and indenes. The vapor-phase mutagens present in diesel exhaust appeared to be more mutagenic in tester strain TA100 (with S9) compared to TA98, suggesting that the mutagenic compounds are different than those responsible for mutagenic activity in particulate matter where TA98 mutagenicity dominates. Specific mutagenic activities of the total vapor-phase component in TA 100 (with or without S9) were very similar to those of the total particulate component, suggesting that the vapor-phase of diesel exhaust may be an important source of mutagenic compounds in the environment.

1,3 Butadiene, a vapor phase component of environmental tobacco smoke, accelerates arteriosclerotic plaque development.

Our recent results support predictions from epidemiology studies that thousands of excess heart disease-related deaths result yearly in the United States from involuntary exposure to environmental tobacco smoke (ETS). Limited exposures of cockerels to ETS significantly accelerate arteriosclerosis. Despite little direct in vivo support, tar fraction rather than vapor phase compounds are considered largely responsible for the plaque-promoting effects of cigarette smoke. Here, we evaluate the effects of two ETS components on plaque development: the vapor phase component, 1,3 butadiene, and the tar component, the tobacco-specific N-nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). At relatively high doses, injected NNK is carcinogenic in rodents. Epidemiology studies have identified increased mortality from arteriosclerotic heart disease among black men working in the butadiene rubber industry. Neither butadiene nor NNK has been tested experimentally for a possible role in plaque development. Cockerels inhaled butadiene (20 ppm; 16 weeks) or were injected biweekly with NNK (10 mg/kg, 16 weeks). Control cockerels were exposed to filtered air or were injected with the NNK solvent dimethylsulfoxide. Plaque incidence, prevalence, location, and size were determined double-blind. NNK had no significant effect on any of these measurements. In contrast, butadiene elicited a statistically significant increase in plaque size comparable to that seen after steady-state exposure to ETS from 5 cigarettes. (1) This study represents the first time that a single cigarette smoke component has been demonstrated to accelerate arteriosclerosis, at a dose that is environmentally relevant. (2) The plaque-promoting components of ETS may reside in the vapor phase. (3) The cockerel model should be valuable in understanding the mechanism underlying the reported increases in heart disease deaths among black workers in the butadiene rubber industry.

南阿賀油田におけるフィンガープリント法地化学調査

Most conventional soil-gas methods use instantaneous samples, in which the sample collected represents the soil-gas composition at the moment of collection. Short-term meteorological influences may yield noisy data. The K-V Fingerprint Technique couples time-integrated soil-gas collection with mass-spectrometric analysis and pattern recognition, and thus overcomes the problems inherent in most other gas geochemical methods.Three surveys using the K-V Fingerprint Technique have been conducted in the Minami-Aga Oil Field Case Study (Niigata Prefecture, Japan) in 1986, 1987, and 1988. The results of the three surveys show an apical geochemical anomaly over the same area of the Minami-Aga Oil Field every year. The factor spectrum derived from factor analysis of the mass spectra shows that light aromatic hydrocarbons are responsible for the geochemical anomalies.Furthermore, a few samples collected over the known producing area and samples of vapor-phase compounds present in equilibrium with some crude-oil samples were analyzed by GC-MS to verify the compositional relationship between surface soil gases and the oil in the reservoir.Based on those analyzed data, it was concluded that hydrocarbon gases from the reservoir at 2, 300 meters reach the surface in less than 20 years.

Genotoxicity and PAC analysis of particulate and vapour phases of environmental tobacco smoke

Samples of indoor air were collected from an office room (88 m 3) both before smoking and during experimental smoking of 96 cigarettes by 10 persons within 6 h. The particulates were collected on glass-fibre filters and the vapour-phase compounds on XAD-2 resin. The samples were extracted with acetone and analysed quantitatively for polycyclic aromatic compounds and qualitatively with GC-MS. The extracts of filters and XAD-2 resins were fractionated into neutral/acidic and 2 basic (strong and weak bases) fractions; all these fractions were tested with the sister-chromatid exchange (SCE) assay in Chinese hamster ovary (CHO) cells and with the Salmonella/microsome test (strain TA98). Total concentrations of PAC were 205 ng/m 3 in the background sample and 1207 ng/m 3 after contamination by cigarette smoking. The total PAC concentrations were 4–6 times higher in the vapour phase than in the particulate phase. The fractions of the particulate samples collected before smoking showed mainly marginal genotoxic activity, whereas after smoking their genotoxicity increased dramatically. The fractions of the vapour phase samples were not genotoxic before smoking, but after smoking the neutral/acidic and strong basic fractions induced responses in both assays. The SCE assay was more sensitive towards the vapour-phase mutagens of environmental tobacco smoke (ETS). The relative responses of the two bioassays were different: in the Ames test, the highest responses were obtained with the two basic fractions, whereas the fraction containing neutral and acidic compounds was the most potent in the SCE assay. In the Salmonella test, the mutagenic activity was mainly detected with metabolic activation, while the induction of SCE in CHO cells was also seen without an exogenous metabolic activation system.

Analysis of Ambient Concentrations of Organic Vapors with a Passive Sampler

Volatile organic compounds can contribute to the failure of electronic equipment in both switching offices and data centers. They can also be useful indicators of ventilation needs. Only within the past decade have ambient concentrations of volatile organics been measured routinely. In standard sampling approach, a pump is used to pull a known volume of air through an adsorbent. This study examines a sampling procedure that does not use a pump, but instead depends on molecular diffusion for eventual contact between the vapor phase compounds and the charcoal sorbent (passive sampling). The technique is both simpler and less expensive than active sampling with a pump. This method has been validated for low-level sampling over extended time intervals. This study demonstrates that collected amounts vary linearly with airborne concentrations for sampling intervals in excess of four weeks: even after eight weeks of sampling at typical ambient concentrations, the amount of material collected does not approach th...

Behavior of diffusion, permeation and sorption of flavor compounds in vapor phase with polyethylene film.

Behavior of diffusion, permeation and sorption of flavor compounds in vapor phase with polyethylene film.

Studies of organic material present in the exhaust stream of an experimental fluidized bed coal combustor

Abstract Organic components of effluents from a fluidized bed coal combustor were sampled by collecting vapor phase compounds on a Tenax polymer adsorbent trap and particulate samples with a concentric electrostatic precipitator (CESP). Samples of ash collected by the effluent cleanup devices were also analyzed. Samples were extracted to isolate the organic components. Extracts were characterized by gas chromatography to quantitate extractable hydrocarbons and by gas chromatography‐mass spectrometry to obtain molecular weights and tentative identification of components. The effluent contained higher concentrations of extractable hydrocarbons in the vapor phase than associated with particles.

Collection and Analysis of Trace Organic Vapor Pollutants in Ambient Atmospheres. the Performance of a Tenax gc Cartridge Sampler for Hazardous Vapors

Abstract The performances of several sorbents as collection media for the quantitative concentration and analysis of volatile, hazardous, vapor-phase compounds from ambient atmospheres were evaluated under a variety of conditions relevant to field sampling. Tenax GC was found to be superior to other sorbents in most cases. The effects of humidity, background air pollution, repeated re-use of sorbent, and transportation and storage of collected samples were investigated.