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PubMed2004

Multiple functions of inducible plant volatiles.

A considerable amount of the carbon fixed by plants is emitted back into the atmosphere as volatile organic compounds (VOCs). Novel inducible VOCs released from plants after biotic or abiotic stresses temporarily increase total emissions of carbon substantially. As well as having a role in attracting the natural enemies of herbivores, inducible VOCs are also involved in plant-to-plant signalling, pathogen defence and ozone quenching, as well as tropospheric ozone and fine-particle aerosol formation. To relate these diverse observations to active plant defence, a conceptual framework of four functional levels (plant cellular interspace, leaf boundary layer, ecosystem and atmosphere) of inducible VOCs is proposed to aid understanding of the evolutionary role of inducible plant volatiles.

Atmosphere↗

PubMed2006

Characterization of a mini membrane inlet mass spectrometer for on-site detection of contaminants in both aqueous and liquid organic samples.

A mini membrane inlet mass spectrometer (mini-MIMS) of a total weight of 12 kg was constructed using a miniature Multipole mass spectrometer, a small vacuum system and a flexible flat sheet membrane inlet, where the exposed membrane area can be changed by a factor of 80. The variable membrane area together with the possibility of operating the Multipole at pressures up to 1 x 10(-3) Torr made it possible to test the system with three microporous membranes (cellulose, polyether sulfone and polypropylene) normally not compatible with standard electron ionization MIMS systems and a standard non-porous polydimethylsiloxane membrane. We found that the hydrophilic cellulose and polyether sulfone membranes had selectivity characteristics opposite to those of the standard silicone membrane. They demonstrated preferential detection of hydrophilic compounds in hydrophobic organic solvents, whereas the silicone membrane preferentially detects hydrophobic organic compounds in aqueous solution. Using the cellulose membrane, organic contaminants and water could be detected in organic solvents at 10-100 ppm levels by weight, the relative high detection limits primarily caused by interference from a high chemical background from the solvent. When being used with the standard silicone membrane the mini-MIMS behaved just like most standard MIMS systems with detection limits of volatile organic compounds in water at concentrations just below 1 ppm. The hydrophobic microporous polypropylene membrane was not found to be useful with the mini-MIMS.

Journal Article↗

PubMed2000

Application of a purge and trap TDS-GC/MS procedure for the determination of emissions from flame retarded polymers.

Emissions of volatile organic compounds (VOCs) from different thermoplastic polymers used in electrotechnical applications were investigated using a purge and trap procedure that involved adsorption on Tenax GR. Results were compared to those for an operating TV set monitored in a test chamber. The analyses were in both cases carried out using thermodesorption gas chromatography with mass spectrometric detection (TDS-GC/MS). Substances identified were monomers, volatile additives, or related compounds. Special attention was given to the detection of halogenated compounds. Their origin was studied using reference samples and synthetic standards.

Air Pollutants↗

PubMed2004

Air concentrations of VOCs in portable and traditional classrooms: results of a pilot study in Los Angeles County.

Recent state and federal public school class-size reduction initiatives, increased elementary and pre-K enrollment driven by population growth and immigration, and limited resources for capital projects, modernization, and maintenance at aging schools have increased the prevalence of prefabricated, portable classrooms (portables). At present, approximately one of three California students are taught in portables, whose use is especially prevalent in more populated counties such as Los Angeles, home to the nation's second largest school district. Limited data existed on chemical compound air concentrations, and thus exposures, inside American public schools. Measurements have been limited, usually performed in complaint schools, and varied in sampling protocols and analysis methods. To address a school environment and children's health issue of present concern, an assessment of public school portables was conducted in Los Angeles County. Seven schools in two school districts were recruited, from which 20 classrooms--13 portables, seven in main buildings--were randomly selected. We report indoor air concentrations of 21 target toxic and odorous volatile organic compounds (VOCs), including formaldehyde and acetaldehyde, measured with passive samplers (DNSH PAKS and 3M OVM 3500) in the cooling and heating seasons between June 2000 and June 2001. None of the measured indoor air formaldehyde concentrations exceeded the existing California Air Resources Board guideline (50 ppb, or 60 microg/m(3)). The main sources of aldehydes in classrooms, especially portables, were likely interior finish materials and furnishings made of particleboard without lamination. Indoor air VOC concentrations were generally low in this pilot study. The four most prevalent VOCs measured were toluene, m-/p-xylene, alpha-pinene, and delta-limonene; likely indoor sources were personal, teaching, and cleaning products. Future schools research should attempt larger samples over larger geographical areas.

Acetaldehyde↗

PubMed2003

Accumulation of airborne hexachlorocyclohexanes and DDT in pine needles.

The accumulation of alpha- and gamma-hexachlorocyclohexanes (HCHs) and p,p'-DDT in Scots pine needles was measured simultaneously with the concentrations in the surrounding air. All three compounds accumulate during the entire life span of the needles. For p,p'-DDT the general accumulation is overlaid by a concentration peak during winter, probably related to particle deposition. For the HCHs the accumulation is overlaid by a seasonal pattern with rapid accumulation during spring and summer months and constant concentrations during winter months. The concentrations of alpha-HCH in the air were more or less constant during the whole sampling period, whereas gamma-HCH shows an air concentration peak in spring and early summer. Air concentrations of p,p'-DDT were for the most part below the detection limit. There is little evidence of revolatilization from the needles, with the exception of a small decline of gamma-HCH concentration in summer after the peak air concentrations. The high accumulation rate of the HCHs during the warm season correlates with high levels of volatile organic compounds (VOCs) in the needles. We suggest that the variation of VOC content in the needles cause seasonal variation of the air-plant partitioning coefficient. An additional complicating factor is that the dry weight of the needles has to be corrected for the yearly variation of starch content. The results presented here question models of uptake of airborne contaminants by plants that assume rapid equilibria between the air and plants.

Air↗

PubMed2006

Volatiles of bacterial antagonists inhibit mycelial growth of the plant pathogen Rhizoctonia solani.

Bacterial antagonists are bacteria that negatively affect the growth of other organisms. Many antagonists inhibit the growth of fungi by various mechanisms, e.g., secretion of lytic enzymes, siderophores and antibiotics. Such inhibition of fungal growth may indirectly support plant growth. Here, we demonstrate that small organic volatile compounds (VOCs) emitted from bacterial antagonists negatively influence the mycelial growth of the soil-borne phytopathogenic fungus Rhizoctonia solani Kühn. Strong inhibitions (99-80%) under the test conditions were observed with Stenotrophomonas maltophilia R3089, Serratia plymuthica HRO-C48, Stenotrophomonas rhizophila P69, Serratia odorifera 4Rx13, Pseudomonas trivialis 3Re2-7, S. plymuthica 3Re4-18 and Bacillus subtilis B2g. Pseudomonas fluorescens L13-6-12 and Burkholderia cepacia 1S18 achieved 30% growth reduction. The VOC profiles of these antagonists, obtained through headspace collection and analysis on GC-MS, show different compositions and complexities ranging from 1 to almost 30 compounds. Most volatiles are species-specific, but overlapping volatile patterns were found for Serratia spp. and Pseudomonas spp. Many of the bacterial VOCs could not be identified for lack of match with mass-spectra of volatiles in the databases.

Anti-Bacterial Agents↗

PubMed2005

Increase of the purification efficiency of biofilters by the use of a complementary ionisation step.

The biofilter and the ionisation system are two oxidative treatment techniques for purification of waste gas streams with low concentrations of volatile organic compounds. In this paper, the authors present the investigations of an ionisation technique aimed at increasing the efficiency of the reduction of the odorant concentration in waste gas streams from biological waste treatment plants. The objective is to enable advanced odour emission reduction and to adjust the existing biofilters to stricter requirements. In a first step, the odorous substances which are major contributors to the overall odorant concentration are identified on basis of various emission data sets with the help of a method of life cycle impact assessment. Thereby limonene, alpha-pinene, ethyl butyrate and dimethyl disulphide were identified as crucial indicators. In a second step, experimental investigations using limonene as a model compound were conducted to gain an understanding of the ionisation process itself and at last for the evaluation of the system.

Air Ionization↗

PubMed2004

Simultaneous quantitative determination of benzene, toluene, and xylenes in water using mid-infrared evanescent field spectroscopy.

Attenuated total reflection mid-infrared spectroscopy is applied for simultaneous detection and quantification of the environmentally relevant analytes benzene, toluene, and the three xylene isomers. The analytes are enriched into a thin polymer membrane coated onto the surface of an internal reflection waveguide, which is exposed to the aqueous sample. Direct detection of analytes permeating into the polymer coating is performed by utilizing evanescent field spectroscopy in the fingerprint range (>10 microm) of the mid-infrared (MIR) spectrum (3-20 microm) without additional sample preparation. All investigated compounds are characterized by well-separated absorption features in the evaluated wavelength regime. Hence, data evaluation was performed by integration of the respective absorption peaks. Limits of detection lower than 20 ppb (v/v) for all xylene isomers, 45 ppb (v/v) for benzene, and 80 ppb (v/v) for toluene have been achieved. The straightforward experimental setup and the achieved detection limits for these environmentally relevant volatile organic compounds in the low-ppb concentration range reveal a substantial potential of MIR evanescent field sensing devices for on-line in situ environmental analysis.

Benzene↗

PubMedDate not supplied

A simple, reliable method for the determination of chlorinated volatile organics in human breath and air using glass sampling tubes.

A method for determining chloroform, 1,1,1-trichloroethane, carbon tetrachloride, and trichloroethene in breath samples was developed. It consisted of collecting samples in 40-ml. glass-silanized tubes that were 16-in. long and had a 0.64-in. diameter. The ends tapered, resulting in a tube with a 1/4-in. diameter that was 1 3/4-in. long; each end had a shutoff valve attached. One end had a strip of rubber tube attached to the shutoff valve for collecting the breath sample, and the other end contained a 1/4-in. Swagelok nut with a rubber septum for withdrawing the sample. Samples were withdrawn using a pressure-lock, gastight syringe, and they were injected onto a gas chromatograph fitted with an electron-capture detector. The analytes were stable for at least 22 days in these tubes. The method detection limit was determined to be 0.03, 0.08, 0.04, and 0.04 pg/ml. for chloroform, 1,1,1-trichloroethane, carbon tetrachloride, and trichloroethene, respectively. Precision, based on 13 injections, was determined to be 13% for 0.09 pg chloroform, 13% for 0.21 pg 1,1,1-trichloroethane, 8% for 0.16 pg carbon tetrachloride, and 14% for 0.1 pg trichloroethene. In all, the proposed method is a sensitive and reliable one for determining volatile organic compounds in breath and a method that can also be applied to air sampling.

Air Pollutants↗

PubMed2002

Volatile metabolites produced by three strains of Stachybotrys chartarum cultivated on rice and gypsum board.

Stachybotrys chartarum (atra) is a toxigenic fungus frequently found in water-damaged buildings. Although microbial volatile organic compounds (MVOCs) produced by Aspergillus, Penicillium, and other fungi have been investigated extensively, little information exists on what MVOCs can be produced by S. chartarum. In this study, three strains of S. chartarum isolated from water-damaged residential homes in Cleveland, Ohio, were cultivated on rice and gypsum board. Air samples were collected after one, two, three, four, and six weeks of cultivation using Tenax TA tubes. Unique MVOCs were determined and other alcohols, ketones, and terpenes were also investigated using gas chromatography/mass spectrometry after thermal desorption from the sampling tube. Four unique MVOCs, 1-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, and thujopsene, were detected on rice cultures, and only one of them (1-butanol) was detected on gypsum board cultures. For a given strain, volatiles were considerably different with different cultivation media. Concentration profiles of the volatile compounds varied among compounds; however, each compound exhibited corresponding concentration trends between the strains. In comparison with our previous studies of five Aspergillus species on gypsum board under the same experimental conditions, fewer unique MVOCs were produced by S. chartarum, and they were quite different. It thus may be possible to use marker-unique MVOCs as a fingerprint to distinguish fungi in indoor environments once enough information becomes available. Our findings also indicate that volatiles produced by S. chartarum may represent a relatively small fraction of the total volatiles present in problem buildings where Aspergillus spp., Penicillium spp., and other fungi usually coexist.

Biomarkers↗

PubMed2004

Outdoor, indoor, and personal exposure to VOCs in children.

We measured volatile organic compound (VOC) exposures in multiple locations for a diverse population of children who attended two inner-city schools in Minneapolis, Minnesota. Fifteen common VOCs were measured at four locations: outdoors (O), indoors at school (S), indoors at home (H), and in personal samples (P). Concentrations of most VOCs followed the general pattern O approximately equal to S < P less than or equal to H across the measured microenvironments. The S and O environments had the smallest and H the largest influence on personal exposure to most compounds. A time-weighted model of P exposure using all measured microenvironments and time-activity data provided little additional explanatory power beyond that provided by using the H measurement alone. Although H and P concentrations of most VOCs measured in this study were similar to or lower than levels measured in recent personal monitoring studies of adults and children in the United States, p-dichlorobenzene was the notable exception to this pattern, with upper-bound exposures more than 100 times greater than those found in other studies of children. Median and upper-bound H and P exposures were well above health benchmarks for several compounds, so outdoor measurements likely underestimate long-term health risks from children's exposure to these compounds.

Air Pollutants↗

PubMed2003

Headspace solid-phase microextraction-gas chromatography-mass spectrometry applied to quality control in multilayer-packaging manufacture.

A method based on headspace solid-phase microextraction-gas chromatography-mass spectrometry is proposed for the quality control of multilayer packaging and its manufacturing process. Volatile organic compounds (VOCs) are produced in the manufacturing process of the packaging. They can cause organoleptic problems or modify the properties of the packaging depending on the nature and the amount of the VOCs formed. The quantification using packaging samples with a known VOC concentration for the calibration is proposed in order to reduce the analysis time, and the method is validated using a statistical test. Finally, the method is applied to the determination of odour-responsible compounds in multilayer packaging samples obtained under different extrusion-coating conditions, i.e. type of extruder, type of polymer and extrusion speed.

Calibration↗

PubMed2004

Biofilm in water pipelines; a potential source for off-flavours in the drinking water.

Volatile organic compounds (VOC) are identified in natural biofilm established in plastic pipes used at the drinking water supply. Odour potent VOCs such as ectocarpene, dictyopterene A and C', geosmin, beta-ionone, 6-methyl-5-hepten-2-one, menthol and menthone were prominent compounds in biofilm in the distribution network and at raw water test sites, and are associated with algae and cyanobacteria present in the raw water source.

Biofilms↗

PubMed2002

Investigation of the volatile organic substances that cause the characteristic odor of pentachlorophenol treated wood utility poles.

The nature of the volatile organic compounds that could be at the origin of the characteristic odor of treated wood utility poles was investigated by the study of compositional changes in the chromatographic profiles of fresh-pentachlorophenol (PCP) solvent samples and weathered samples collected from an in-service red pine pole. Over 99 peaks were identified in the chromatogram of the fresh solvent from which a large portion of the C3-, C4-, C5-, C6-alkylbenzene isomers and early eluting n-alkanes was missing from the analysis of weathered samples. Three domains in the chromatographic profile (volatile, semivolatile, and nonvolatile components) were confirmed by assessing the headspace of fresh-PCP solvent samples using direct syringe sampling and solid-phase microextraction. A first level of field validation was achieved using an emission cell for measuring substances emanating from sapwood specimens at different temperatures. The average latent heat of vaporization (deltaHvap) of the PCP-solvent components was estimated at 99.9 kJ/mol from these results. Finally, the analysis of airborne substances at a treating plant and a utility pole storage site confirmed that the C4-, C5-, and C6-alkylbenzene isomers could contribute to the characteristic odor perceived by humans.

Air Pollutants↗

PubMed2006

Short-term distributions of reduced sulfur compounds in the ambient air surrounding a large landfill facility.

In order to explore the environmental behavior of reduced sulfur compounds (RSC) as malodorous components emitted from diverse source processes, the distribution characteristics of four sulfur (S) compounds - hydrogen sulfide (H2S), methyl mercaptan (CH3SH), dimethyl sulfide (DMS: (CH3)2S), and dimethyl disulfide (DMDS: (CH3)2S2) - were investigated in a municipal landfill area. In the course of this study, their ambient concentration levels were measured during two time periods from 13 individual spots selected as a function of distance from the center of the landfill site. The results generally indicated the absolute dominance of H2S over the other S compounds investigated (up to 5 km radius) such that their mean values were found as 1415 (H2S), 148 (DMS), 20.6 (CH3SH), and 14.4 ppt (DMDS). When our data were compared in terms of either varying distance from the source or relationship with meteorological conditions, the H2S data sets were most evident to reflect the potential effects of strong source processes in the landfill environment, relative to other S gases (or to volatile organic compounds measured concurrently). The results of this study further indicated the relatively good correspondence between the measured H2S concentration level and humans' intuitive sensory of odor and nuisance.

Air Pollutants↗

PubMed2005

Perturbation of voltage-sensitive Ca2+ channel function by volatile organic solvents.

The mechanisms underlying the acute neurophysiological and behavioral effects of volatile organic compounds (VOCs) remain to be elucidated. However, the function of neuronal ion channels is perturbed by VOCs. The present study examined effects of toluene (TOL), trichloroethylene (TCE), and perchloroethylene (PERC) on whole-cell calcium current (ICa) in nerve growth factor-differentiated pheochromocytoma (PC12) cells. All three VOCs affected ICa in a reversible, concentration-dependent manner. At +10-mV test potentials, VOCs inhibited ICa, whereas at test potentials of -20 and -10 mV, they potentiated it. The order of potency for inhibition (IC50) was PERC (270 microM) > TOL (720 microM) > TCE (1525 microM). VOCs also changed ICa inactivation kinetics from a single- to double-exponential function. Voltage-ramp experiments suggested that VOCs shifted ICa activation in a hyperpolarizing direction; this was confirmed by calculating the half-maximal voltage of activation (V1/2, act) in the absence and presence of VOCs using the Boltzman equation. V(1/2, act) was shifted from approximately -2 mV in control to -11, -12, and -16 mV by TOL, TCE, and PERC, respectively. Similarly, VOCs shifted the half-maximal voltage of steady-state inactivation (V1/2, inact) from approximately -16 mV in control to -32, -35, and -20 mV in the presence of TOL, TCE, and PERC, respectively. Inhibition of ICa by TOL was confirmed in primary cultures of cortical neurons, where 827 microM TOL inhibited current by 61%. These data demonstrate that VOCs perturb voltage-sensitive Ca2+ channel function in neurons, an effect that could contribute to the acute neurotoxicity of these compounds.

Action Potentials↗

PubMed1999

A healthy home environment?

Over the past seven years, the U.S. Environmental Protection Agency has consistently ranked indoor air pollution among the top five risks to public health. One of the most dangerous indoor air pollutants is carbon monoxide (CO). CO can be lethal, but perhaps more important, many people suffer ill health from chronic, often undetected exposure to low levels of this gas, resulting in fatigue, headache, dizziness, nausea, and vomiting. Another dangerous pollutant is volatile organic compounds (VOCs), which come from sources including building products, cleaning agents, and paints. One VOC, formaldehyde, can act as an irritant to the conjunctiva and upper and lower respiratory tract. Formaldehyde is also known to cause nasal cancer in test animals.

Air Pollution, Indoor↗

PubMed2003

Search criteria and rules for comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry analysis of airborne particulate matter.

Direct thermal desorption-gas chromatography-time-of-flight mass spectrometry (DTD-GC-TOFMS) and comprehensive two-dimensional (2D) gas chromatography-time-of-flight mass spectrometry (GC x GC-TOFMS) was applied for characterisation of semi-volatile organic compounds (SVOC) in fine particulate matter (PM), with a diameter of up to 2.5 microm (PM2.5), from ambient air in Augsburg, Germany. DTD-GC-TOFMS measurements on the SVOC in PM2.5 are done on a daily basis (time series over several years). The data will be used in an epidemiological study questioning the influence of SVOC in PM2.5 on ambient aerosol related health effects. The outcome of the first measurements periods is that the organic inventory in the ambient aerosol can undergo drastic fluctuations, e.g. due to meteorological influences or specific emission sources. This includes also the large fraction of chromatographically not resolved peaks (unresolved carbonaceous matter (UCM)). The UCM fraction contains about 70% of the SVOC mass in PM2.5. GC x GC-TOFMS is a suited technique to study the nature of the yet unidentified compounds forming the UCM. The considerably increased chromatographic resolution in GC x GC allows separation of many UCM compounds while the TOFMS supplies mass spectral data of all separated compounds. However, the data sets are getting enormously complex. In a typical PM2.5 sample from Augsburg more than 15,000 peaks can be detected. Thus, it is important to classify the observed GC x GC peaks by rational means. A classification procedure based on GC x GC retention times and the fragmentation patterns is suggested. With a preliminary classification procedure it is already possible to group compounds with some certainty into substance classes. After some further development, this approach can be used for classifying GC x GC data, e.g. for environmental and epidemiological studies.

Aerosols↗