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PubMed2005

[Passive remote sensing of VOC in atmosphere by FTIR spectrometry].

The paper expatiates the passive remote sensing experiment of VOC in atmosphere by FTIR spectrometry, a mode of simulated spectra for pollution gas in a complicated environment is proposed, and the detecting limit of passive FTIR remote sensing is discussed. Using this measurement technique and the data analysis method, the authors can obtain column density and effective radiation temperature of target-gas that does not require a previously measured background spectrum.

Air Pollutants↗
PubMedDate not supplied

[Indoor pollution and biological monitoring of volatile organic compounds (VOC)].

Indoor air is a complex mixture of chemicals and airborne particles. Volatile Organic Compounds (VOC), a broad class of chemicals including diverse compounds such as Aldehydes, Terpenes, Aromatic and Aliphatic Hydrocarbons and Halogenated Volatile Organics, are an important category of indoor air pollutants. The evaluation of exposure to low doses of Chloroform and Benzene through the measurement of Chloroform and Benzene in urine was performed. Results show that biological monitoring may be helpful in indoor environmental studies in non occupational situations.

Air Pollution, Indoor↗
PubMed2006

Cognitive impairment and olfactory panic from occupational exposure to VOCs.

BACKGROUND: A Canadian government clerical worker in her early thirties developed frontal lobe dysfunction from inhalation of volatile organic compounds off-gassed during an office renovation. METHODS: Pulmonary function, bronchial provocation, allergy testing, and a brain (SPECT) scan were performed. RESULTS: SPECT scanning showed frontotemporal hypoperfusion and neuropsychologic testing revealed deficits in verbal learning and poor organizational memory. CONCLUSIONS: A significant component of this worker's impairment was the development of "olfactory panic," a debilitating aversion to odor accompanied by symptoms of panic. The Ontario Workplace Safety and Insurance Appeals Tribunal granted entitlement for her cognitive difficulties and olfactory panic as a result of her toxic exposure.

Adult↗
PubMed2005

On-line multi-bed sorption trap for VOC analysis of large-volume vapor samples: injection plug width, effects of water vapor and sample decomposition.

A multibed on-line sorption trap is used to preconcentrate organic vapors from air samples and inject the analytes into a GC separation column. Injection plug widths depend on the boiling point for the lipophilic compounds and on the polarity and boiling point for the polar compounds. Injection plug widths are sufficiently small (0.7-0.8 s) as to allow the direct injection of the most volatile compounds into the GC column without the need for a second focusing device. The presence of water in the samples has an effect on the retention of polar compounds by the trap. However, this effect is reproducible for a fixed water content and so can be overcome by using calibration standards under the same conditions of humidity as the samples. The thermal decomposition of many volatile organic compounds in an on-line sorption trap during the GC analysis of air samples is examined. The results show that degradation of unstable compounds is governed by the amount of heat transferred to the compounds during desorption (i.e., applied temperature and pulse duration). The use of an on-line trap results in the immediate transfer of desorbed compounds to the analytical column, which can reduce the formation of artifacts.

Journal Article↗
PubMed1996

Fungal colonization of fiberglass insulation in the air distribution system of a multi-story office building: VOC production and possible relationship to a sick building syndrome.

Complaints characteristic of those for sick building syndrome prompted mycological investigations of a modern multi-story office building on the Gulf coast in the Southeastern United States (Houston-Galveston area). The air handling units and fiberglass duct liner of the heating, ventilating and air conditioning system of the building, without a history of catastrophic or chronic water damage, demonstrated extensive colonization with Penicillium spp and Cladosporium herbarum. Although dense fungal growth was observed on surfaces within the heating-cooling system, most air samples yielded fewer than 200 CFU m-3. Several volatile compounds found in the building air were released also from colonized fiberglass. Removal of colonized insulation from the floor receiving the majority of complaints of mouldy air and continuous operation of the units supplying this floor resulted in a reduction in the number of complaints.

Air Conditioning↗
PubMed2003

Use of a gas-sensor array for detecting volatile organic compounds (VOC) in chemically induced cells.

An application of gas sensors for rapid bioanalysis is presented. An array of temperature-modulated semiconductor sensors was used to characterize the headspace above a cell culture. Recombinant Saccharomyces cerevisiae yeast cells, able to respond to 17 beta-estradiol by producing a reporter protein, were used as a model system. Yeast cells had the DNA sequence of the human estrogen receptor stably integrated into the genome, and contained expression plasmids carrying estrogen-responsive sequences and the reporter gene lac-Z, encoding the enzyme beta-galactosidase. The sensor-response profiles showed small but noticeable discrimination between cell samples induced with 17 beta-estradiol and non-induced cell samples. The sensor array was capable of detecting changes in the volatile organic compound composition of the headspace above the cultured cells, which can be associated with metabolic changes induced by a chemical compound. This finding suggests the possibility of using cross-selective gas-sensor arrays for analysis of drugs or bioactive molecules through their interaction with cell systems, with the advantage of providing information on their bioavailability.

Biosensing Techniques↗
PubMed1999

Characterization of alpha-pinene-degrading microorganisms and application to a bench-scale biofiltration system for VOC degradation

A study was conducted to isolate and characterize monoterpene-degrading microorganisms and apply them to a biofiltration unit for use in degrading high levels of alpha-pinene. Soil from a monoterpene-contaminated site was used with enrichment culture techniques to recover a consortium of bacteria able to utilize alpha-pinene as the sole source of carbon and energy. The Biolog system was utilized to identify the bacteria as Pseudomonas fluorescens and Alcaligenes xylosoxidans. Aerobic growth and biodegradation studies confirmed that rapid growth and biodegradation were being achieved with alpha-pinene. Complete degradation of alpha-pinene was achieved in 36 h with a maximum rate of degradation of 3.9 mg/L/h. The microorganisms were placed in a biofiltration column and demonstrated good removal of alpha-pinene from an air stream at concentrations averaging 295 ppmv. A nitrogen test was performed and confirmed that the removal of alpha-pinene was due to biological activity. Given the ability of these microorganisms to utilize high levels of alpha-pinene, they will be used in a coupled treatment system using a physical/chemical adsorption/desorption unit coupled to a biofiltration column. Often, biofiltration studies are performed using much lower levels of analyte in the influent air stream. However, the ability of these microorganisms to utilize higher levels of compounds expands the capabilities for future coupled biofiltration systems. During future studies, high flow rates with low levels of analyte will be concentrated so that a higher analyte concentration and lower flow rate can be utilized with the biofilter.http://link.springer-ny. com/link/service/journals/00244/bibs/37n2p151.html

Journal Article↗
PubMed2004

Rapid identification of microbial VOCs from tobacco molds using closed-loop stripping and gas chromatography/time-of-flight mass spectrometry.

Several microbial volatile organic compounds (MVOCs) that can serve as potential chemical markers for microbial contamination in tobacco have been identified. Four different fungal species, Aspergillus niger (AN), A. ornatus (AO), Pencillium chrysogenum (PC) and Rhizopus stolonifer (RS), commonly reported in moldy tobacco were cultured and screened for MVOCs. Because the MVOCs emitted by a microbial species are substrate specific, the fungal strains were separately grown on potato dextrose agar (PDA) and tobacco products. MVOCs from the mold cultures grown on PDA and tobacco products were extracted using closed-loop stripping analysis (CLSA) and identified by gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS). Some of the prominent tobacco mold markers identified by this method include: 1-octen-3-ol; 2-octen-1-ol; 2-methyl-1-butanol; 3-methyl-1-butanol; 1-octene and 2-pentanone. In particular, 1-octen-3-ol was detected in all the mold cultures and moldy tobacco samples analyzed. Olfactory evaluation of 1-octen-3-ol indicated a characteristic musty odor and the odor threshold was determined to be approximately 200 ng/ml. The limits of detection for 1-octen-3-ol using GC/TOF-MS and GC/mass selective detector (MSD) in the full-scan mode and selected ion monitoring (SIM) mode were investigated. The CLSA-GC/TOF-MS demonstrates a fast, sensitive and semi-quantitative analytical technique for screening tobacco materials for the presence of mold via chemical markers of microbial contamination.

Aspergillus↗
PubMed2006

Detection of aromatic catabolic gene expression in heterogeneous organic matter used for reduction of volatile organic compounds (VOC) by biofiltration.

A qualitative procedure of purified DNA/RNA co-extraction from complex organic matter, used as biofilter support for removing volatile organic compounds, was set up and applied to detect xylene monooxygenase gene expression by RT-PCR. A DNA/RNA extraction protocol based on a combination of sample lyophilization pre-treatment and CTAB--phenol/chloroform extraction procedure was optimized for the recovery of purified nucleic acids [100-500 ng DNA (10 kb) and 0.5-2 microg of rRNA 16S from 100 mg matrix]. PCR and RT-PCR protocols were established to detect xylene monooxygenase gene expression starting from differentially induced organic matrices obtained by biofiltration technology. This work allowed the microbial degradation activities in heterogeneous organic solid media to be studied and suggests a rapid method to follow specific biological activities during solid and/or semisolid organic substrates biotransformation.

Air Microbiology↗
PubMed2004

Characterising sources and sinks of rural VOC in eastern France.

Fifty non-methane hydrocarbons (NMHC) and seventeen carbonyl compounds were measured at a French rural site from 1997 to 2001, as part of the EMEP programme. Data handling was based on an original source-receptor approach. First, the examination of the levels and trends was completed by the comparison of the seasonal distribution of rural and urban VOC/acetylene ambient ratios. This analysis has shown that most of the compounds derived from mixing and photochemical transformation of mid-range transported urban pollutants from the downwind urban area. Then, identified sources and sinks were temporally apportioned. Urban air masses mixing explains, at least, 80% of the wintertime levels of anthropogenic NMHC and isoprene. In summer, photochemistry dominates the day-to-day distribution of anthropogenic NMHC whilst summertime isoprene is also controlled by in-situ biogenic emissions. Then, the results of C(1)-C(3) carbonyls were discussed with respect to their direct biogenic and anthropogenic emissions and photochemical production through the [carbonyl/auto-exhaust tracers] emission ratio. Diluted vehicle exhaust emissions mainly contribute to the total content of lower aldehydes in winter while other processes control lower ketones. Secondary production is predominant in summer with at least a 50% high intensity. Its dependence upon temperature and radiation is also demonstrated. Finally, the importance of the primary and secondary biogenic production of acetone and formaldehyde is assessed. In particular, biogenic contribution would explain 37 +/- 25% of acetone levels in summer.

Air Pollutants↗
PubMed2004

Enhanced photocatalytic degradation of VOCs using Ln3+-TiO2 catalysts for indoor air purification.

Two types of lanthanide ion-doped titanium dioxide (Ln3+-TiO2) catalysts including La3+-TiO2 and Nd3+-TiO2 were prepared by a sol-gel method. The effects of the lanthanide ion doping on the crystal structure, surface area, adsorption properties, pore size distribution, and surface chemical state of the catalysts were investigated by means of XRD, BET, and XPS. As results, the crystal size decreased significantly, while the specific surface area, t-plot total surface area, micropore volume, and the total pore volume increased owing to the lanthanide ion doping. The nitrogen adsorption-desorption isotherms of the catalysts showed that the N2 adsorption ability of the Ln3+-TiO2 catalysts was better than the TiO2 catalyst. Among them, the 0.7% Ln3+-TiO2 catalysts demonstrated the highest adsorption ability. The photocatalytic activity of the catalysts was investigated in the experiments of the photocatalytic degradation of benzene, toluene, ethylbenzene and o-xylene (BTEX) in a gaseous phase. The photocatalytic efficiency of the TiO2 catalysts with the lanthanide ion doping was remarkably enhanced by BTEX removal. The 1.2% Ln3+-TiO2 catalysts achieved the highest photocatalytic activity. The enhanced photodegradation of BTEX is possibly due to the improved adsorption ability and the enhanced electron-hole pairs separation due to the presence of Ti3+ on the surface of Ln3+-TiO2 catalysts and the electron transfer between the conduction band/defect level and lanthanide crystal field state.

Adsorption↗
PubMed2006

Effect of void structure of photocatalyst paper on VOC decomposition.

TiO2 powder-containing paper composites, called TiO2 paper, were prepared by a papermaking technique, and their photocatalytic efficiency was investigated. The TiO2 paper has a porous structure originating from the layered pulp fiber network, with TiO2 powders scattered on the fiber matrix. Under UV irradiation, the TiO2 paper decomposed gaseous acetaldehyde more effectively than powdery TiO2 and a pulp/TiO2 mixture not in paper form. Scanning electron microscopy and mercury intrusion analysis revealed that the TiO2 paper had characteristic unique voids ca. 10 microm in diameter, which might have contributed to the improved photocatalytic performance. TiO2 paper composites having different void structures were prepared by using beaten pulp fibers with different degrees of freeness and/or ceramic fibers. The photodecomposition efficiency was affected by the void structure of the photocatalyst paper, and the initial degradation rate of acetaldehyde increased with an increase in the total pore volume of TiO2 paper. The paper voids presumably provided suitable conditions for TiO2 catalysis, resulting in higher photocatalytic performance by TiO2 paper than by TiO2 powder and a pulp/TiO2 mixture not in paper form.

Acetaldehyde↗
PubMed2004

Fungal biocatalysts in the biofiltration of VOC-polluted air.

Gas-phase biofilters used for the treatment of waste gases were originally packed with compost or other natural filter beds containing indigenous microorganisms. Over the past decade much effort has been made to develop new carrier materials, more performant biocatalysts and new types of bioreactors. Elimination capacities reached nowadays are 5 to 10 times higher than those originally reported with conventional compost biofilters. With the recently developed inert filter beds, inoculation is a prerequisite for successful start-up and operation. Either non-defined mixed cultures or pure bacterial cultures have originally been used. The search for efficient fungal biocatalysts started only a few years ago, mainly for the biofiltration of waste gases containing hydrophobic compounds, such as styrene, alpha-pinene, benzene, or alkylbenzenes. In this review, recently isolated new fungal strains able to degrade alkylbenzenes and other related volatile organic pollutants are described, as well as their major characteristics and their use as biocatalysts in gas-phase biofilters for air pollution control. In biofiltration, the most extensively studied organism belongs to the genus Exophiala, although strains of Scedosporium, Paecilomyces, Cladosporium, Cladophialophora, and white-rot fungi are all potential candidates for use in biofilters. Encouraging results were obtained in most of the cases in which some of those organisms were present in gas-phase biofilters. They allow reaching high elimination capacities and are resistant to low pH values and to reduce moisture content.

Air Pollution↗
PubMed2004

Plant VOC emissions: making use of the unavoidable.

All plants emit substantial amounts of phytogenic volatile organic compounds (PVOCs), which include alkanes, alkenes, alcohols, aldehydes, eters, esters and carboxylic acids. Defence, communication and/or protection against extreme conditions have been proposed as reasons for these emissions. However, Rosenstiel and colleagues have recently proposed that emission of PVOCs represents a metabolic 'safety valve' by preventing the unnecessary sequestration of phosphates. Additionally, Niinemets and colleagues suggest that the emission rates of some PVOCs are determined by the principal physicochemical characteristics of the emitted compounds, such as their solubility, volatility and diffusivity, rather than by physiological mechanisms, such as their synthesis rates. These two new studies lead to the hypothesis that there is not necessarily a specific role for every PVOC emitted, given that their emission is unavoidable as result of their volatility. However, in some cases, natural selection has worked to take advantage of this volatility.

Journal Article↗
PubMed1998

Measurement and analysis of nicotine and other VOCs in indoor air as an indicator of passive smoking.

In Finland the Tobacco Act was amended in 1994 to include workplaces. The developed method for estimating passive smoking, or environmental tobacco smoke utilised the widely used measurement of volatile organic compounds in indoor air quality surveys. The method is based on active sorbent sampling, thermal desorption and gas chromatography/mass selective detection (GC/MS) analysis and it has been tested in a chamber and in field conditions. The method can be used simultaneously to measure volatile organic compounds and exposure to tobacco smoke. We recommend nicotine, collected by active sampling, as an indicator for the evaluation of the exposure to environmental tobacco smoke spreading from smoking areas.

Air Pollution, Indoor↗