Volatile Organic Compounds In Air Research Articles

Detection of Volatile Organic Compounds in Upland peat by Means of Proton-transfer-reaction Mass Spectrometry

This research represents the results of the detection of volatile organic compounds (VOCs) in the sphagnum moss and peat from two upland bogs located in Germany. Proton-transfer-reaction mass spectrometry (PTR-MS), used for the research, is a high-sensitive method, which permit to detect low concentrations of VOCs in ambient air. Along with natural VOCs of peat plants (generally sphagnum moss), the results of the study showed the presence of anthropogenic VOCs emissions like butanol, toluene, and benzene. This fact testifies about the capability of peat moss to accumulate these compounds. Possible sources of these VOCs in the peat samples can be agricultural machines and the traffic of the nearest roads.

Relationship between sources and patterns of VOCs in indoor air

People spend most of their daytime in indoor environments. Their activities influence the composition of the indoor air by emitting volatile organic compounds (VOCs). The increasing number of different VOCs became the focus of attention in recent years as the question arises from the relationship between exposure to air pollutants and diseases. The present study of flats in Leipzig (Germany) is based on measurements of 60 different VOCs and is unique in the field of indoor air quality due to its enormous size of samples (n=2 242) and questionnaire data. The main purpose of our analysis was to identify the sources and patterns that characterize airborne VOCs in occupied flats. We combined two methods, principal components analysis (PCA) and non–negative matrix factorization (NMF), to assign compounds to their origin and to understand the coinstantaneous existence of several VOCs. PCA clustering provided a source apportionment and yielded 10 principal components (PCs) with an explained variance of 72%. However, real indoor air quality is often affected by combined sources. NMF reveals characteristic compositions of VOCs in indoor environments and emphasizes that constantly recurring structures are not single sources, but rather fusions of them, so called patterns. Interpreting these sources, we realized that homes were strongly influenced by ventilation, human activities, furnishings, natural processes (such as solar radiation) or their combinations. The very large set of samples and the combination with questionnaires applied on this comprehensive assessment of VOCs allows generalizing the results to homes in middle–scale cities with minor industrial pollution. As a conclusion, single VOC–dose–response relationships are inopportune for situations when indoor sources occur in combination. Further studies are necessary to assess associated health risks.

Ambient air and #8217;s volatile organic compounds and potential ozone formation in urban area, Bangkok, Thailand

Aims: The study were evaluated for the presence of the ambient air volatile organic compounds (VOCs) (benzene, toluene, ethylbenzene and xylene [BTEX] and carbonyl compounds [CCs]) at the university, roadside and residential areas in order to assess the applicability for prediction of ozone formation in ambient air of these in urban area, Bangkok, Thailand. Methods: The ambient air VOCs levels were evaluated by the gas chromatography/flame ionization detector for BTEX analysis and the high-performance liquid chromatography/UV-visible detector for CCs analysis. Results: The comparison of VOCs levels in those areas showed that the roadside area had the highest VOCs levels (of toluene and benzene levels), while the residential area had the lowest of benzene level. However, the benzene levels of all studied-areas were higher than ambient air quality standard. The contributions of hydrocarbons to local ozone formation potential were evaluated in terms of maximum incremental reactivity. Our results showed that the largest contributors to ozone production in Bangkok were toluene and formaldehyde (possibly from the emission of biofuel motor vehicle exhaustion). The roadside area also had the highest ozone formation potential. The aromatic hydrocarbon was the major contribution to anthropogenic emissions of VOCs. However, anthropogenic emissions and photochemistry are mainly transported VOCs to ozone formation. Conclusion: There was the highest VOCs level at roadside area and also was the largest amount of ozone level from chemical reactions. Therefore, it is a need for more research and the environmental protection policy because it may have serious health risk from these pollutants in these areas.

Volatile organic compounds analyzed by gas chromatography-deep ultraviolet spectroscopy

Exhaled breath contains thousands of volatile organic compounds (VOCs) of which the composition varies depending on status of the individual and the environment. Different metabolic processes within the body produce volatile substances that are released into the blood. When the blood reaches the lungs the products are released into lung tissue and airways.Also, chronic inflammation and/or oxidative stress can result in the excretion of volatile compounds that generate unique VOC patterns. Therefore, measuring the presence of VOCs in exhaled air (breathomics), for clinical diagnosis and monitoring purposes has gained increased interest over the last years.This paper describes one methodology based on gas chromatography (GC) and deep ultraviolet (DUV) spectroscopy. Spectra of compounds found in exhaled breath are presented.

CFD Simulation and Modeling of Membrane‐Assisted Separation of Organic Compounds from Wastewater

AbstractThe extraction of volatile organic compounds (VOC) from water in porous hollow fibers was simulated with toluene, a hazardous material. The system to be simulated included a VOC stream and air as stripping gas, which were contacted using a porous hollow‐fiber membrane contactor. To model the process, the contactor was considered as three compartments, including shell side, porous membrane, and tube side. The model equations were derived and solved using computational fluid dynamics of momentum and mass transfer in all zones of the contactor. The profiles of concentration and pressure were obtained for the VOC in the hollow fibers.

Rapid monitoring of volatile organic compounds: a comparison between gas chromatography/mass spectrometry and selected ion flow tube mass spectrometry

The gold standard for monitoring volatile organic compounds (VOCs) is gas chromatography/mass spectrometry (GC/MS). However, in many situations, when VOC concentrations are at the ppmv level, there are complicating factors for GC/MS. Selected ion flow tube mass spectrometry (SIFT-MS) is an emerging technique for monitoring VOCs in air. It is simpler to use and provides results in real time. Three different experiments were used for the comparison. First SIFT-MS was applied to monitor the concentrations of 25 VOCs in a mixture at concentrations up to 1 ppmv using only a generic database for known kinetic data of three reagent ions (H3O(+), NO(+) and O2(+)) with each VOC. In experiment 2, a side-by-side comparison was made of 17 VOCs at concentrations between 1 ppmv and 5 ppbv after small corrections had been made to the SIFT-MS kinetic data. In a third experiment, a side-by-side comparison examined two groups of samples received for commercial analysis. In experiment 1, 85% of the VOC concentrations were within 35% of their stated values without any calibration of the SIFT-MS instrument. In experiment 2, the two techniques yielded good correspondence between the measured VOC concentrations. In experiment 3, good correlation was found for VOCs from three of the samples. However, interferences from some product ions gave over-reported values in one sample from the SIFT-MS instrument. These three experiments showed that GC/MS was better suited to monitoring samples containing large numbers of VOCs at high concentrations. In all other applications, SIFT-MS proved simpler to use, was linear with concentration over a much wider concentration range than GC/MS and provided faster results.

Source apportionment and ozone formation potential of volatile organic compounds in Lagos (Nigeria)

Concentrations of volatile organic compounds (VOCs) of the city air in Oba Akran road, Lagos were investigated. The chlorinated VOCs and xylene in Oba Akran were high. The average benzene/toluene ratio in Oba Akran was 1.7 suggesting that vehicular emission was a possible VOC source in most areas of Oba Akran. The toluene/(m+p-xylene) ratio also suggests a common source of toluene and xylene at these sites, presumably organic solvent used by industries located at Oba Akran. Our results showed that 7.10 tons of CO 2 equivalents of VOCs are being emitted per year from Oba Akran. Xylenes were found to be the largest contributor to the ozone formation followed by trichloroethylene. A multivariate statistical analysis (Factor analysis extracted with Principal Component Analysis) has been applied to a set of data, and it was found that the main principal components, extracted from the air VOC pollution data, were related to gasoline and oil combustion/industrial activities.

Elimination of Toluene Vapours using Natural Zeolite Treated by Copper Oxide

Background: Volatile organic compounds (VOCs) are the most frequent air contaminants which are produced due to industrial processes such as production of chemicals, petrochemical industries and their related industries. These compounds are harmful (even in low concentrations) not only for the environment but also for the human health. One method to control these contaminants is using catalytic beds. In this study we used modified natural Zeolite (Clinoptilolite) to eliminate toluene vapours. Methods: In this study, at first natural Zeolite were modified with cooper ions and calsined thermally. Then, the effect of variables such as toluene concentration, reactor temperature, and flow rate on toluene vapours elimination were surveyed by using a tubular stainless steel reactor and modified. Results: It was found that cooper oxide, as a catalyst, led to the considerable decrease in combustion temperature of toluene vapours. Of course, increasing the space velocity (or flow rate) and toluene concentration led to decreasing Zeolite bed efficiency. Conclusion: Regarding the presence of many natural storage of Clinoptilolite in Iran, it seems that its modification with cooper oxide could be a good catalyst for eliminating of VOCs in air.

Effects of arc rotation speed on BTX decomposition by atmospheric pressure plasma

This study was conducted to investigate the decomposition of volatile organic compounds in air by the rotating arc plasma system. The rotating arc plasma decomposed benzene, toluene, and m-xylene (BTX) gases diluted in air. The effects of the gas flow rate and arc rotation speed on conversion rate and energy efficiency were evaluated by high speed images and Fourier transform infrared spectroscopy. Perfect conversions of toluene and m-xylene into environmentally benign species were achieved at the lowest waste gas flow rate of 20L/min, while the conversion rate of benzene was 79% under the same operating conditions due to the highest chemical bond strength of benzene among BTX. Although the conversion rate decreased with increasing the gas flow rate, the energy efficiency had an optimal gas flow rate, which influenced arc rotation speed. In addition, the oxidation rates of BTX were examined based on analysis of carbon oxides generated under different operating conditions.

Estimation of experimental results for monitoring data on VOCs (Volatile Organic Compounds) in indoor air of daycare centers in Seoul

Estimation of experimental results for monitoring data on VOCs (Volatile Organic Compounds) in indoor air of daycare centers in Seoul

Evaluation of impact of shale gas operations in the Barnett Shale region on volatile organic compounds in air and potential human health risks

Shale gas exploration and production (E&P) has experienced substantial growth across the U.S. over the last decade. The Barnett Shale, in north-central Texas, contains one of the largest, most active onshore gas fields in North America, stretching across 5000square miles and having an estimated 15,870 producing wells as of 2011. Given that these operations may occur in relatively close proximity to populated/urban areas, concerns have been expressed about potential impacts on human health. In response to these concerns, the Texas Commission on Environmental Quality established an extensive air monitoring network in the region. This network provides a unique data set for evaluating the potential impact of shale gas E&P activities on human health. As such, the objective of this study was to evaluate community-wide exposures to volatile organic compounds (VOCs) in the Barnett Shale region. In this current study, more than 4.6million data points (representing data from seven monitors at six locations, up to 105 VOCs/monitor, and periods of record dating back to 2000) were evaluated. Measured air concentrations were compared to federal and state health-based air comparison values (HBACVs) to assess potential acute and chronic health effects. None of the measured VOC concentrations exceeded applicable acute HBACVs. Only one chemical (1,2-dibromoethane) exceeded its applicable chronic HBACV, but it is not known to be associated with shale gas production activities. Annual average concentrations were also evaluated in deterministic and probabilistic risk assessments and all risks/hazards were below levels of concern. The analyses demonstrate that, for the extensive number of VOCs measured, shale gas production activities have not resulted in community-wide exposures to those VOCs at levels that would pose a health concern. With the high density of active wells in this region, these findings may be useful for understanding potential health risks in other shale play regions.

Detection of an extended human volatome with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry.

BackgroundComprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC-TOF MS) has been proposed as a powerful new tool for multidimensional analysis of complex chemical mixtures. We investigated GCxGC-TOF MS as a new method for identifying volatile organic compounds (VOCs) in normal human breath.MethodsSamples of alveolar breath VOCs and ambient room air VOC were collected with a breath collection apparatus (BCA) onto separate sorbent traps from 34 normal healthy volunteers (mean age = 40 yr, SD = 17 yr, male/female = 19/15). VOCs were separated on two serial capillary columns separated by a cryogenic modulator, and detected with TOF MS. The first and second dimension columns were non-polar and polar respectively.ResultsBCA collection combined with GC×GC-TOF MS analysis identified approximately 2000 different VOCs in samples of human breath, many of which have not been previously reported. The 50 VOCs with the highest alveolar gradients (abundance in breath minus abundance in ambient room air) mostly comprised benzene derivatives, acetone, methylated derivatives of alkanes, and isoprene.ConclusionsCollection and analysis of breath VOCs with the BCA-GC×GC-TOF MS system extended the size of the detectable human volatile metabolome, the volatome, by an order of magnitude compared to previous reports employing one-dimensional GC-MS. The size of the human volatome has been under-estimated in the past due to coelution of VOCs in one-dimensional GC analytical systems.

Lowering TVOC is necessary to prevent sick building syndrome

Background: Sick-building syndrome (SBS) is a range of symptoms such as eye irritation, sore throat, and headaches that occur when entering a newly constructed or remodelled building. Volatile organic compounds (VOCs) are suspected to be one of the major causes of SBS. Therefore, the Ministry of Health, Labour and Welfare of Japan set the indoor air guideline values about 13 VOCs to prevent SBS. However, the number of the SBS patients has not decreased although the concentration levels of the 13 VOCs have become extremely low in recent years. Aims: The aim of this study is to examine the kind of VOCs and the concentration level of the total VOCs (TVOCs) in the current houses and buildings. Methods: Chemiless Town is a model town constructed under the concept of “Environmental Preventive Medicine” in the campus of Chiba University, Japan. In Chemiless Town, in which houses and buildings are constructed with as fewer chemicals as possible, eight Laboratory Houses (LHs) were set up for the purpose of researching the VOCs from building and interior materials. To find the causing chemicals of SBS, 81 VOCs in indoor air of the 29 rooms of the LHs were analyzed and calculated from April 2007 to December 2012.Results: The concentration levels of each VOC were extremely variable depending on the materials of the houses and the seasons. When TVOC concentration value was higher than 1,000?g/m3 or below 100?g/m3, 75% of the TVOCs was the 10 highest concentration levels of VOCs. Also, when TVOC concentration value was higher than 1,000?g/m3, 75% of the TVOCs was occupied by unregulated VOCs.Conclusion: It is important to lower the TVOCs to prevent SBS; however, it is difficult if only 13 regulated VOCs are analyzed. To lower the TVOCs, unregulated VOCs also should be analyzed and lowered.

Application and limitations of a mass transfer VOC emission model for a dry building material

Volatile organic compound (VOC) emission from building materials into air has been quantified, characterized and modeled. Internal diffusion of VOC through a material based on Fick's law of diffusion is the basis for mass transfer modeling of diffusive emission used to estimate VOC concentrations in air over time. Current mass transfer models have been shown to appropriately estimate air VOC concentrations at approximate room temperature, while other research has shown that temperature has a profound effect on the diffusion coefficient, D, of VOC in a material. Here, a mass transfer model is operated at 23 °C and 40 °C using input parameters applicable for each temperature. The model estimates are validated against environmental test chamber data for styrene emission from a vinyl ester resin thermoset composite material. The model correlates well with the 23 °C chamber data, but underestimates chamber data by as much as 10−4 at 264 h for the 40 °C modeling. This suggests that the model requires adjustment for predicting VOC air concentrations at temperatures other than 23 °C.

Conditions for the optimal analysis of volatile organic compounds in air with sorbent tube sampling and liquid standard calibration: demonstration of solvent effect

The combined use of sorbent tubes (ST) and thermal desorption (TD) has become the common practice for the trace-level analysis of gaseous volatile organic compounds (VOCs). In this research, the potential bias in VOC analysis due to the solvent introduced into the system as a liquid standard (LS) is examined in three stages by analyzing LSs of 19 VOCs in methanol solvent against a three-bed ST (Tenax TA, Carbopack B, and Carboxen 1000). In experimental stage 1, LS made at four concentration levels (between 10 and 150 ng μL(-1)) were each analyzed at four injection volumes (1, 2, 5, and 10 μL) based on a vaporization method. In experimental stage 2, calibration was also conducted by direct injection over an extended concentration range at two volumes, 1 and 10 μL. In experimental stage 3, the response factors (RF) of a single analyte mass were compared across the four injection volumes and between two injection methods. These results were analyzed to explore the complex relationship between variables such as LS volume, target/solvent chemical type, sorbent strength, and prepurge condition. There was no change in the ST/TD performance up to 2 μL of LS. However, as the injection volume increased up to 5 μL, a notable shift in RF and retention time occurred (e.g., for benzene and methyl ethyl ketone). At the maximum injection volume (10 μL), a significant reduction in sensitivity is evident for all compounds, e.g., 50 % drops relative to 1 μL injection. As such, the TD performance tends to deteriorate with increasing volume of methanol initially loaded on the ST. Although the dominant fraction of solvent was removed by two prepurge steps, residue caught in the strong sorbent fraction is still found to exert an effect on the subsequent analysis, e.g., delayed retention, sensitivity reduction, or disappearance of certain compounds.

A Study on Present Conditions and Improvement Alternatives of Vapor Recovery Unit of StageII at Gas Stations

Gas station vapour is one of the most prominent sources of the volatile organic compounds in air of urban areas. This paper studied the current management statues of vapour recovery systems of stageII at gas stations and suggested the improvement plans through analysis of case studies. Some 97.3% gas stations of target stations, which have to install the vapor recovery unit of stageII, was completed by end of 2012. But approximately 18.5% of them did not pass the regular inspection caused improper operations and equipment obsolescence. There is a need for government's technical support, regular training and management manual for gas station workers in order to be operating normaly of the vapor recovery unit of stageII. Furthermore, it is necessary to expand the mandatory installation area for the vapor recovery unit of stageII. For this, an expansion scenario analysis performed. The results showed that the expansion must be preferentially replied in 10 cities more than population of 500,000 when it was economic with a cost-benefit ratio was 1.43.

VOC sorption and diffusion behavior of building materials

In this study 25 different building materials often used in timber constructions (wood based panels, gypsum boards, vapor barriers, adhesive tapes, insulation materials and sealants) were investigated with regard to their adsorption, desorption and diffusion behaviour towards volatile organic compounds (VOC). The materials were exposed to four, respectively five selected VOCs typically found in indoor air: hexanal, butyl acetate, p-xylene, nonane and α-pinene. Adsorption and desorption properties were investigated under static conditions, whereas the diffusion behavior was examined in a 0.225 m3 emission chamber with an air exchange rate of 1 h−1. The results of the experiments indicate that some building products have a high potential to reduce VOCs in indoor air. Apart from the vapor barriers, two insulating materials and one plasterboard, all tested materials represented an adsorption efficiency of about 50 % or higher related to the injected VOC standards. Materials with high adsorption capacity bound substances strongly and desorbed them less, whereas less adsorbing materials acted inversely. The obtained results indicate that material properties and processing play a considerable role in diffusion behavior of building materials.

Volatile organic compounds (VOCs) in air from Nisyros Island (Dodecanese Archipelago, Greece): Natural versus anthropogenic sources

This study presents the chemical composition of VOCs in air and gas discharges collected at Nisyros Island (Dodecanese Archipelago, Greece). The main goals are i) to discriminate between natural and anthropogenic VOC sources and ii) to evaluate their impact on local air quality. Up to 63 different VOCs were recognized and quantitatively determined in 6 fumaroles and 19 air samples collected in the Lakki caldera, where fumarolic emissions are located, and the outer ring of the island, including the Mandraki village and the main harbor. Air samples from the crater area show significant concentrations of alkanes, alkenes, cyclic, aromatics, and S- and O-bearing heterocycles directly deriving from the hydrothermal system, as well as secondary O-bearing compounds from oxidation of primary VOCs. At Mandraki village, C6H6/Σ(methylated aromatics) and Σ(linear)/Σ(branched) alkanes ratios <1 allow to distinguish an anthropogenic source related to emissions from outlet pipes of touristic and private boats and buses.

Investigation of qualitative and quantitative of volatile organic compounds of ambient air in the Mahshahr Petrochemical Complex in 2009.

Volatile organic compounds (VOCs) are human-made chemicals widely spread in the environment and produced by petrochemical industries and petroleum refineries. The aim of this research was to evaluate the distribution of VOCs in the ambient air of Mahshahr Petrochemical Complex, Iran. This study was a cross-sectional research performed in 2009. We used the method numbered 1501, 1500, 2000, 1003, 1005, 1010, 2555, 1300 and 1400 of the National Institute of Occupational Safety and Health (NIOSH) for the sampling and analysis of compounds in the air. A total of 204 samples were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) and a Gas Chromatography-Flame Ionization Detector (GC-FID). The mean of concentrations of the pollutants in the winter is less than in summer and a strong variation occurred among the sampling site, attributed to the change in meteorology. The results indicated high concentrations of benzene in most factories. In addition, a significant difference occurred between the concentrations of the compounds in the ambient air inside and outside the factories in both seasons (P<0.050). It seems that the atmospheric conditions of the workplace affect the spreading of the pollutants, causing the concentration of the pollutants in the summer to be higher than in the winter. In addition, the frequent prevailing wind speed in the region plays a major role in the distribution of the pollutants from Mahshahr Petrochemical factories.

A Wireless Hybrid Chemical Sensor for Detection of Environmental Volatile Organic Compounds

A hybrid sensor for monitoring volatile organic compounds (VOCs) in air is developed. The device combines two orthogonal sensing principles, selective molecular binding with a microfabricated quartz tuning fork detector and separation of analytes with a column. The tuning fork detector is functionalized with molecular imprinted polymers for selective binding to benzene, toluene, ethylbenzene, and xylenes (BTEX), and the separation column provides further discrimination of the analytes for real world complex sample analysis. The device is wireless, portable, battery-powered, and cell-phone operated, and it allows reliable detection in parts per billion (ppb) by volume-levels of BTEX in the presence of complex interferents. The hybrid device is suitable for occupational, environmental health, and epidemiological applications.