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PubMed2005

Preliminary investigation of using volatile organic compounds from human expired air, blood and urine for locating entrapped people in earthquakes.

A preliminary investigation on the possibility of using volatile organic compounds (VOCs) determination of expired air, blood and urine, for the early location of entrapped people in earthquakes, has been carried out. A group of 15 healthy subjects has been sampled. The identification of a common "core" of substances might provide indications of human presence that can be used for the development of a real time field analytical method for the on site detection of entrapped people. Expired air samples have been analyzed by thermal desorption GC/MS and VOCs from blood and urine by headspace SPME-GC/MS. Acetone was the only compound found common in all three matrices. Isoprene was found in both expired air and blood samples. Acetone and isoprene along with a number of saturated hydrocarbons were among the major constituents identified in expired air analysis. Various ketones (2-pentanone, 4-heptanone, 2-butanone) were also determined over urine specimens. Using the techniques and methods of field analytical chemistry and technology appears to be the proper approach for applying the results of the present study in real situations.

Acetone↗

PubMed2001

Disinfection by-products and volatile organic compounds in the water supply system in Athens, Greece.

On a monthly basis, on a one year period, disinfection by-products (DBPs) and volatile organic compounds (VOCs) were measured in raw water and in treated water of four water treatment plants (WTP) as well as from eight representative points of the distribution network of Athens. Liquid-liquid extraction (LLE) method followed by gas chromatography (GC) with electron capture detection (ECD) and mass spectrometry (MS) was used for the determination of the DBPs, while the purge-and-trap (PAT) technique followed by GC-MS was used for the determination of the VOCs. The DBPs that have been studied included trihalomethanes (THMs), haloacetonitriles (HANs), haloketones (HKs), chlorate hydrate (CH) and chloropicrin (CP), while forty-one VOCs were also studied including THMs. Chloroform (CM), dichlorobromomethane (DCBM), chlorodibromomethane (CDBM) were the major organic compounds found in all treated water samples. HANs, HKs, CH and CP were detected in treated samples but at lower concentrations.

Disinfectants↗

PubMed2006

The fate of chlorinated volatile organic compounds in aeration basins using recirculated aeration: a pilot-plant evaluation.

The fate of chloroform, which was chosen to represent chlorinated volatile organic compounds sometimes found in publicly owned wastewater treatment works, has been followed in a pilot aeration basin utilizing aeration recirculation. Tests were conducted using real wastewaters spiked with two different concentration levels of chloroform and operated at conditions similar to those of a large-scale aeration basin of the Mill Creek Wastewater Treatment Plant in Cincinnati, Ohio. Aeration recirculation levels of 0, 25, 50, and 75% were used to evaluate the concept that aeration recirculation can be an effective method of reducing the release of these toxic compounds to the atmosphere. Data obtained demonstrated that the concentration of chloroform in the off-gas increased as the recirculation ratio increased, but that the total mass emission rate to the atmosphere decreased due to the decreased off-gas volumetric flow rate. Biodegradation in the pilot plant increased by 183% for the 75% recirculation level compared to 0% recirculation. Mass balance analysis results indicated that 60% of chloroform emissions could be reduced with 75% recirculation ratio with little or no effect of dissolved oxygen concentration.

Air↗

PubMed1991

Gas chromatographic-mass spectrometric analysis of urban-related aquatic and airborne volatile organic compounds. Study of the extracts obtained by water closed-loop stripping and air adsorption with charcoal and polyurethane foam.

The distribution of volatile organic compounds (VOC) in urban-influenced air and river waters was investigated. The aquatic VOC were extracted with the closed-loop stripping technique (CLST) and the airborne compounds were studied using two methods, charcoal and polyurethane foam adsorption. In both types of samples, C1-C5 alkylbenzenes and n-alkanes constitute the two major VOC groups, and the presence of these groups indicates a predominance of petroleum products in these two environmental compartments. Chlorinated compounds such as polychlorobenzenes, polychloronaphthalenes and hexachlorobutadiene are abundant in water samples, whereas tetrachloroethene is the predominant chlorinated airborne VOC. The compounds collected with each sampling system can be described in terms of ranges of volatility. These ranges (expressed as mmHg vapour pressure at 25 degrees C) can be defined approximately as 140 (methylcyclopentane)-0.65 (n-undecane) for charcoal, 5.1 (n-nonane)-0.000061 (n-docosane) for polyurethane foam and 29 (toluene)-0.000029 (n-eicosane) for the CLST. Parallel air sampling with charcoal and polyurethane foam is therefore needed to cover a VOC range similar to that afforded by the CLST in water.

Adsorption↗

PubMed2004

A new method for the rapid determination of volatile organic compound breakthrough times for a sorbent at concentrations relevant to indoor air quality.

The use of sorbents has been proposed to remove volatile organic compounds (VOCs) present in ambient air at concentrations in the parts-per-billion (ppb) range, which is typical of indoor air quality applications. Sorbent materials, such as granular activated carbon and molecular sieves, are used to remove VOCs from gas streams in industrial applications, where VOC concentrations are typically in the parts-per-million range. A method for evaluating the VOC removal performance of sorbent materials using toluene concentrations in the ppb range is described. Breakthrough times for toluene at concentrations from 2 to 7500 ppb are presented for a hydrophobic molecular sieve at 25%) relative humidity. By increasing the ratio of challenge gas flow rate to the mass of the sorbent bed and decreasing both the mass of sorbent in the bed and the sorbent particle size, this method reduces the required experimental times by a factor of up to several hundred compared with the proposed American Society of Heating, Refrigerating, and Air-Conditioning Engineers method, ASHRAE 145P, making sorbent performance evaluation for ppb-range VOC removal more convenient. The method can be applied to screen sorbent materials for application in the removal of VOCs from indoor air.

Adsorption↗

PubMed2005

[Application of mathematical models for determination of volatile organic compounds emission from flooring adhesives].

An environmental chamber with controlled temperature, relative humidity, and air exchange was used to evaluate emissions of volatile organic compounds (VOC) from three flooring solvent-based adhesives. Gas chromatograph equipped with flame ionization detector was employed to measure VOC emission. The temporal change in concentration of VOC emitted from each adhesive was observed and double-exponential model was compared with a first-order emission decay model in their ability to describe measured emission factors of adhesives. It was demonstrated that the double exponential model better describes emission characteristic for experimental data than first-order model does.

Adhesives↗

PubMed2003

[Measurement of emission rate of formaldehyde and volatile organic compounds(VOCs) from building materials by the small chamber method].

A small chamber for measuring the emission rate of formaldehyde gas and volatile organic compounds(VOCs) from building materials was developed, and formaldehyde and VOCs (toluene and xylene) concentrations emitted from particle boards(PB), medium density fiber-boards(MDF) and wall papers were measured. The emission rates measured by the chamber method were compared with the values by the desiccator method, several modified desiccator methods and the perforator method. The emission rate of formaldehyde increased with time and it became constant after about 20 hours. On the other hand, the emission rate of VOCs decreased with time. A good correlation was obtained on the emission rate of formaldehyde between the chamber method and the conventional desiccator method. The correlation coefficient between the perforator method and the chamber method was also high, but the correlation was low for surface treated materials.

Air Pollution, Indoor↗

PubMed2003

A two-column method for long-term monitoring of non-methane hydrocarbons (NMHCs) and oxygenated volatile organic compounds (o-VOCs).

A method has been developed for concurrent analysis of C2-C7 hydrocarbons and C2-C5 oxygenated volatile organic compounds (o-VOCs) including alcohols, aldehydes, ketones and ethers. A multi-bed, Peltier-cooled adsorbent trap, consisting of Carboxen 1000 and Carbopack B, was used to acquire one sample per hour. Upon injection the sample was split in an approximately 50:50 ratio between a 50 m aluminium oxide (Al2O3) porous layer open tubular (PLOT) column and a 10 m LOWOX column. Eluents from each column were then analysed using flame ionisation detection (FID). Regular calibration of the system was performed using a standard cylinder mixture at the parts per billion by volume (ppbV) level for non-methane hydrocarbons (NMHCs) and a permeation tube method for the oxygenated species. The system is fully automated with NMHC detection limits between 1 and 10 parts per trillion by volume (pptV) and o-VOC detection limits between 10 and 40 pptV.

Absorption↗

PubMed2005

Volatile organic compounds in natural biofilm in polyethylene pipes supplied with lake water and treated water from the distribution network.

The objective of this work was investigation of volatile organic compounds (VOC) in natural biofilm inside polyethylene (HDPE) pipelines at continuously flowing water. VOC in biofilm may contribute to off-flavour episodes in drinking water. The pipelines were supplied with raw lake water and treated water from the distribution network. Biofilm was established at test sites located at two different drinking water distribution networks and their raw water sources. A whole range of volatile compounds were identified in the biofilm, including compounds frequently associated with cyanobacteria and algae, such as ectocarpene, dictyopterene A and C', geosmin, beta-ionone and 6-methyl-5-hepten-2-one. In addition, volatile amines, dimethyldisulphide and 2-nonanone, presumably originating from microorganisms growing in the biofilm, were identified. C8-compounds such as 1-octen-3-one and 3-octanone were believed to be products from microfungi in the biofilm. Degradation products from antioxidants such as Irgafos 168, Irganox 1010 and Irganox 1076 used in HDPE pipes, corresponding to 2,4-di-tert-butylphenol and 2,6-di-tert-butylbenzoquinone, were present in the biofilm.

Biofilms↗

PubMed1999

Spatial distribution of respiratory activity in Pseudomonas putida 54G biofilms degrading volatile organic compounds (VOC).

All over the world, Microbial systems are used to clean soils, waters and air streams that have been contaminated with volatile organic compounds (VOC). Information about the structure and function of the microbes that metabolize these contaminants can be gained by studying these microbial systems. Here we describe the spatial patterns of respiratory activity in Pseudomonas putida 54G aerobic biofilms degrading two VOC, toluene and ethanol. Oxygen concentration profiles within the biofilm were measured using microsensors. These profiles are thought to be most accurate reflection of the structure and function of aerobic microbial biofilms. The degrading process certainly imposed a structural and functional patterns on the microbial biofilm community growing at the expense of the VOC substrate. Cryosectioning coupled with the staining of biofilm samples confirmed a high respiratory activity near the substratum, that decreased towards the biofilm/fluid interface. The accumulation of inactive cells in the outer biofilm layer protects the inner biofilm from high concentrations of toxic compounds and also limits the degradation rate. This stratification phenomenon appeared to be a general pattern for P. putida 54G biofilms degrading VOC.

Biofilms↗

PubMed1998

Sample timing and mathematical considerations for modeling breath elimination of volatile organic compounds.

Real-world exposure measurements are a necessary ingredient for subsequent detailed study of the risks from an environmental pollutant. For volatile organic compounds, researchers are applying exhaled breath analysis and the time dependence of concentrations as a noninvasive indicator of exposure, dose, and blood levels. To optimize the acquisition of such data, samples must be collected in a time frame suited to the needs of the mathematical model, within physical limitations of the equipment and subjects, and within logistical constraints. Additionally, one must consider the impact of measurement error on the eventual extraction of biologically and physiologically relevant parameters. Given a particular mathematical model for the elimination kinetics (in this case a very simple pharmacokinetic model based upon a multiterm exponential decay function that has been shown to fit real-world data extremely well), we investigated the effects on synthetic data caused by sample timing, random measurement error, and number of terms included in the model. This information generated a series of conditions for collecting samples and performing analyses dependent upon the eventual informational needs, and it provided an estimate of error associated with various choices and compromises. Though the work was geared specifically toward breath sampling, it is equally applicable to direct blood measurements in optimizing sampling strategy and improving the exposure assessment process.

Air Pollutants↗

PubMed1990

An analytical method to determine Henry's law constant for selected volatile organic compounds at concentrations and temperatures corresponding to tap water use.

Henry's law constants (H) are needed to model human exposure to Volatile Organic Compounds (VOCs) in indoor air resulting from the use of tap water. This paper presents an experimental method to determine Hs for several common tap water pollutants at concentrations and temperatures used in household water. For 5 VOCs Henry's law constants were obtained simultaneously over the 25 degrees C to 45 degrees C temperature range, providing data on H beyond the currently available data (up to 35 degrees C). Henry's law constants were obtained as the ratio of equilibrium concentrations of VOCs in air and water, using simultaneous sampling from sealed bottles kept at constant temperatures. Air and water samples were concentrated by a purge-and-trap method, thermally desorbed from a Tenax trap, and analyzed with a gas chromatograph with an electron capture detector (GC-ECD). Experimental results agreed well with available literature data.

Chemical Phenomena↗

PubMedDate not supplied

Development and testing of a whole-air sampler for measurement of personal exposure to volatile organic compounds.

A small and relatively lightweight (3.35 kg) whole-air (canister) sampler that can be worn to monitor personal exposures to volatile organic compounds was developed and evaluated. The prototype personal whole-air sampler (PWAS) consists of a 1-l canister, a mass flow controller, two 1.3 amp hour batteries, a DC/DC converter, and an electronics module with a digital display for the sampling set point, actual flow rate, and battery voltage. The sampler (25.5 x 22.5 x 7.5 cm) fits into a laptop computer carrying case and is able to collect a 900 ml sample at a linear flow rate over 12-16 hours. Laboratory tests demonstrated that the sample flow rate was not affected by temperature or the activity of the person wearing the sampler. Recoveries of methylene chloride, chloroform, 1,1,1-trichloroethane, benzene, n-octane, o-xylene, n-decane, and p-dichlorobenzene averaged 89% or better for three final prototype samplers. Recoveries were slightly lower for vinyl chloride (74%) and n-dodecane (82%). The precision for the three prototypes was excellent during laboratory tests with the coefficient of variation (CV) < 10% for all the test compounds. Although the unit was designed for use as a personal whole-air sampling system, it can also be used as an extremely compact microenvironmental whole-air sampler.

Environmental Exposure↗

PubMed2004

Non-linear and non-constant variance calibration curves in analysis of volatile organic compounds for testing of water by the purge-and-trap method coupled with gas chromatography/mass spectrometry.

Currently used operating conditions for analysing volatile organic compounds (VOCs) by purge-and-trap gas chromatography/mass spectrometry (GC/MS) produced non-linear calibration curves with non-uniform variance. Second-order polynomial models therefore had to be used in weighted regression analysis of measurements of replicates spiked at various concentrations. A transparent procedure based on a reported method of very low computational complexity allowed calculation of the parameters of second-order models, confidence bands of regression lines, prediction bands, and confidence intervals of discriminated analyte concentrations. Tolerance intervals were introduced for this last purpose. Critical, detection and quantification levels drawn from the calibration curves were compared with those calculated by the EPA method.

Calibration↗

PubMed2004

Transient release of oxygenated volatile organic compounds during light-dark transitions in Grey poplar leaves.

In this study, we investigated the prompt release of acetaldehyde and other oxygenated volatile organic compounds (VOCs) from leaves of Grey poplar [Populus x canescens (Aiton) Smith] following light-dark transitions. Mass scans utilizing the extremely fast and sensitive proton transfer reaction-mass spectrometry technique revealed the following temporal pattern after light-dark transitions: hexenal was emitted first, followed by acetaldehyde and other C(6)-VOCs. Under anoxic conditions, acetaldehyde was the only compound released after switching off the light. This clearly indicated that hexenal and other C(6)-VOCs were released from the lipoxygenase reaction taking place during light-dark transitions under aerobic conditions. Experiments with enzyme inhibitors that artificially increased cytosolic pyruvate demonstrated that the acetaldehyde burst after light-dark transition could not be explained by the recently suggested pyruvate overflow mechanism. The simulation of light fleck situations in the canopy by exposing leaves to alternating light-dark and dark-light transitions or fast changes from high to low photosynthetic photon flux density showed that this process is of minor importance for acetaldehyde emission into the Earth's atmosphere.

Acetaldehyde↗

PubMed2002

Volatile organic compounds as breath biomarkers for active and passive smoking.

We used real-time breath measurement technology to investigate the suitability of some volatile organic compounds (VOCs) as breath biomarkers for active and passive smoking and to measure actual exposures and resulting breath concentrations for persons exposed to tobacco smoke. Experiments were conducted with five smoker/nonsmoker pairs. The target VOCs included benzene, 1,3-butadiene, and the cigarette smoke biomarker 2,5-dimethylfuran. This study includes what we believe to be the first measurements of 1,3-butadiene in smokers' and nonsmokers' breath. The 1,3-butadiene and 2,5-dimethylfuran peak levels in the smokers' breath were similar (360 and 376 microg/m(3), respectively); the average benzene peak level was 522 microg/m(3). We found higher peak values of the target chemicals and shorter residence times in the body than previously reported, probably because of the improved time resolution made possible by the continuous breath measurement method. The real-time breath analyzer also showed the presence of the chemicals after exposure in the breath of the nonsmokers, but at greatly reduced levels. Single breath samples collected in evacuated canisters and analyzed independently with gas chromatography/mass spectrometry confirmed the presence of the target compounds in the postexposure breath of the nonsmokers but indicated that there was some contamination of the breath analyzer measurements. This was likely caused by desorption of organics from condensed tar in the analyzer tubing and on the quartz fiber filter used to remove particles. We used the decay data from the smokers to estimate residence times for the target chemicals. A two-compartment exponential model generally gave a better fit to the experimental decay data from the smokers than a single-compartment model. Residence times for benzene, 1,3-butadiene, and 2,5-dimethylfuran ranged from 0.5 (1,3-butadiene) to 0.9 min (benzene) for tau1 and were essentially constant (14 min) for tau2. These findings will be useful in models of environmental tobacco smoke exposure and risk.

Adult↗

PubMed2006

Assessment of control strategies for reducing volatile organic compound emissions from the polyvinyl chloride wallpaper production industry in Taiwan.

This study attempts to assess the effectiveness of control strategies for reducing volatile organic compound (VOC) emission from the polyvinyl chloride (PVC) wallpaper production industry. In Taiwan, methyl ethyl ketone, TOL, and cyclohexanone have comprised the major content of solvents, accounting for approximately 113,000 t/yr to avoid excessive viscosity of plasticizer dioctyl phthalate (DOP) and to increase facility in working. Emissions of these VOCs from solvents have caused serious odor and worse air quality problems. In this study, 80 stacks in five factories were tested to evaluate emission characteristics at each VOC source. After examining the VOC concentrations in the flue gases and contents, the VOC emission rate before treatment and from fugitive sources was 93,000 and 800 t/yr, respectively. In this study, the semiwet electrostatic precipitator is recommended for use as cost-effective control equipment.

Air Pollutants↗

PubMed2006

Sample water removal method in volatile organic compound analysis based on diffusion through poly(vinyl fluoride) film.

The humidity caught during air sampling or sample storage causes various problems during volatile organic compound (VOC) analysis and gives unreliable results. In this study, water vapour diffusion capacities through poly(vinyl fluoride) Tedlar, fluoroethylene propylene Teflon and Flex foil film were compared. A new approach to humidity removal has been tested for moderately polluted atmospheres. This approach consists in using the water vapour diffusion property of Tedlar film to remove humidity from bag samples containing a mixture of ten VOCs at 500 ppbv each in a 70% relative humidity atmosphere. The sampling bags were placed in a chamber flushed by a dry air stream at less than 5% relative humidity. After a few hours in the chamber, the samples in the Tedlar bags were dry (relative humidity <5%) and did not show significant VOC loss. This sample water removal (SWR) method is especially interesting as a pretreatment before air sampling on water sensitive adsorbents.

Air Pollutants↗