Kinds Of Volatile Organic Compounds Research Articles

Hydrothermal synthesis of Ce-doped hierarchical flower-like In2O3 microspheres and their excellent gas-sensing properties

Pure and 1–5mol% Ce-doped hierarchical flower-like In2O3 microspheres with uniform sizes were synthesized via environment friendly one-step hydrothermal method. Their phase structures, morphologies properties and element composition were investigated by different kinds of techniques, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectric spectroscopy (XPS). Their gas-sensing properties were tests for several kinds of Volatile Organic Compounds (VOCs). The results indicated that Ce doping could greatly improve sensing performances of In2O3 gas sensors. Among all the samples (0, 1, 3 and 5mol% Ce-doped In2O3), 3mol% Ce-doped In2O3 exhibited the highest response toward 200ppm acetone at 250°C, having a response of 41.8, which was about 4 times higher than pure In2O3. Furthermore, good repeatability and long term stability were achieved, showing its prospect for excellent acetone gas sensor with high performance.

Abstract 5307: Analysis of volatile organic compounds for the diagnosis of lung cancer

Abstract Background: Lung cancer is the leading cause of cancer-related deaths in the world. The prognosis of lung cancer depends on disease detection at an early stage. Recently, effectiveness of lung cancer screening by using low dose computed tomography scanning have been showing. However, it still has problems such as cost of screening and radiation exposure. Thus, less invasive and cost beneficial lung cancer screening procedure would be needed. In this context, several study to understand the efficacy of molecules from expiration of patients as a lung cancer screening were showing, but it was still controversial. In this study, we investigated to determine whether volatile organic compounds (VOC) from patients could be used for the detection for lung cancer by using novel small and unique absorbent material named MonoTrap . Method: The subjects’ gas was collected from skin and exhaled breath in a MonoTrap (GL sciences), and the VOCs were analyzed by gas chromatography/ mass spectrometry (GC/MS). First of all, we preliminary analyzed for both sample from skin and exhaled breath for 12 patients and 11 healthy volunteers to clarify which samples were more sensitive to diagnose lung cancer. Subsequently, each VOC was determined in detail for 7 healthy individuals and 4 lung cancer patients and these values were statistically analyzed. Results: By preliminary study, characteristics of VOC derived from skin were significantly correlated with cancer condition as compared with healthy volunteer by using comprehensive multivariate analysis. Therefore, we performed further quantitative analysis by targeting unique individual molecules derived from skin. In VOCs from skin, Mann-Whitney U test showed that 4-hydroxy-4-methyl-2-pentanone, hexadecane, and acetamide were significantly higher in lung cancer patients (p=0.036, p=0.006, p=0.036, respectively). Conclusion: In this study, we found that 3 kinds of VOCs could be a potential diagnostic biomarkers of lung cancer. Further prospective study is now planning to validate these data using large number samples. Citation Format: Takuya Inoue, Hironori Takagi, Yuki Owada, Yuzuru Watanabe, Mitsuro Fukuhara, Takumi Yamaura, Satoshi Muto, Naoyuki Okabe, Yuki Matsumura, Takeo Hasegawa, Takeda Manami, Atsushi Sato, Hiroyuki Suzuki. Analysis of volatile organic compounds for the diagnosis of lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5307. doi:10.1158/1538-7445.AM2017-5307

Rapid and sensitive on-line monitoring 6 different kinds of volatile organic compounds in aqueous samples by spray inlet proton transfer reaction mass spectrometry (SI-PTR-MS)

Rapid and sensitive monitoring of volatile organic compounds (VOCs) in aqueous samples is very important to human health and environmental protection. In this study, an on-line spray inlet proton transfer reaction mass spectrometry (SI-PTR-MS) method was developed for the rapid and sensitive monitoring of 6 different kinds of VOCs, namely acetonitrile, acetaldehyde, ethanol, acetone, aether, and methylbenzene, in aqueous samples. The response time, limit of detection (LOD), and repeatability of the SI-PTR-MS system were evaluated. The response of the SI-PTR-MS was quite rapid with response times of 31–88 s. The LODs for all these VOCs were below 10 μg/L. The LOD of methylbenzene was 0.9 μg/L, much lower than the maximum contaminant level (MCL) in drinking water. The repeatability of this method was evaluated with 5 replicate determinations. The relative standard deviations (RSDs) were in the range of 0.8–3.1%, indicating good repeatability. To evaluate the matrix effects, the SI-PTR-MS system was employed for on-line monitoring of these 6 VOCs in different aqueous matrices, including lake water, tap water, and waste water. The relative recoveries were in the range of 94.6–106.0% for the lake water, 96.3–105.6% for the tap water, and 95.6–102.9% for the waste water. The results indicate that the SI-PTR-MS method has important application values in the rapid and sensitive monitoring of VOCs in these aqueous samples. In addition, the effect of salt concentration on the extracting efficiency was evaluated. The results showed that the LOD of the SI-PTR-MS could be further decreased by changing the salt concentration.

A better UV light and TiO 2 -PET sheet arrangement for enhancing photocatalytic decomposition of volatile organic compounds

Abstract Although the relative arrangement of a UV light source and immobilized TiO 2 is estimated to strongly affect the photocatalytic decomposition of volatile organic compounds (VOCs), no studies have been published regarding this matter. In the present study, reactor performances were compared between parallel arrangements, where UV lamps are placed in parallel to flat TiO 2 -PET sheets, and circular arrangements, where each glass tube has a UV lamp and a cylindrical TiO 2 -PET sheet closely attached to the inside surface of the tube. In the decomposition of isopropanol, acetone was released into air and decomposed after being readsorbed onto TiO 2 . In the decomposition of toluene, benzaldehyde remained on the surface and inhibited the decomposition. Parallel arrangement generated an area of low UV intensity on TiO 2 -PET sheets, leaving unconverted intermediates on the sheets. Circular arrangement made it possible to irradiate the whole surface of a TiO 2 -PET sheet with high intensity UV light and provided higher rates of VOC decomposition such that intermediates could be decomposed efficiently. To completely decompose VOCs including the intermediates, TiO 2 must be irradiated with strong UV light above a certain threshold that depends on the kind of VOC. The use of the circular arrangement is recommended for the VOC decomposition.

Toluene, Methanol and Benzaldehyde Removal from Gas Streams by Adsorption onto Natural Clay and Faujasite-Y type Zeolite.

A great number of pollution problems come as a result of the emission of Volatile Organic Compounds (VOCs) into the environment and their control becomes a serious challenge for the global chemical industry. Adsorption is a widely used technique for the removal of VOCs due to its high efficiency, low cost, and convenient operation. In this study, the feasibility to use a locally available clay, as adsorbent material to control VOCs emissions is evaluated. Natural clay is characterised by different physical-chemical methods and adsorptive interaction features between VOCs and natural clay are identified. Toluene (T), methanol (M) and benzaldehyde (B) are used here as representatives of three different kinds of VOCs. Adsorption isotherms onto natural clay and faujasite-Y type zeolite (Fau Y) are obtained at room temperature. According to Langmuir model data, maximum adsorption capacities (qm) of Fez natural clay and zeolite toward methanol (M), toluene (T) and benzaldehyde (B) at 300 K are 8, 0.89 and 3.1 mmol g-1, and 15, 1.91 and 13.9 mmol g-1 respectively. In addition, the effect of temperature on the adsorption of toluene onto natural clay is evaluated in the range from 300 to 323K. An increase on temperature reduces the adsorption capacity of natural clay toward toluene, indicating that an exothermic physical adsorption process takes place. The enthalpy of adsorption of toluene onto Fez natural clay was found to be -54 kJ mol-1. A preliminary cost analysis shows that natural clay could be used as an alternative low cost adsorbent in the control of VOCs from contaminated gas streams with a cost of US$ 0.02 kg-1 compared to Fau Y zeolite with US$ 10 kg-1.

Synthesis and improved ethanol sensing performance of CuO/SnO2 based hollow microspheres

A carbon microspheres-templated route was developed to synthesize CuO/SnO2 composites. TEM images exhibit a kind of rough and hollow microspherical morphology with average diameters about 130 nm. All the hollow microspheres are composed of SnO2 and CuO nanoparticles with average diameters about no more than 10 nm. EDX, XPS spectrums indicate the elementary composition of CuO/SnO2 composites and the chemical states of primary elements. The N2 isotherms of 1 mol % CuO/SnO2 show a type-IV isotherm with a H3 type hysteresis loop. The pore size distribution covers a range of 1~10 nm and the BET surface area reaches 18.879 m2/g. Temperature characteristic, transient response, response/recovery speed, selectivity and long term stability for the detection of five kinds of VOCs (volatile organic compounds) were investigated. The sensing mechanism based on surficial reaction and p-n heterojunction depletion region were discussed in detail.

VOC-Sensing Properties of Adsorption/Combustion-Type Micro Gas Sensors Using Mesoporous Alumina Co-Loaded with Pt and Metal Oxide

Volatile organic compounds (VOCs), which are generated from adhesives, resins and paints of new building materials and furniture, cause sick house syndrome such as headache, dizziness and nausea, and thus portable VOC-detecting devices with high sensitivity and selectivity were required as an alternative to large and expensive VOC-analyzing systems. Among various types of VOC sensors, adsorption/combustion-type micro gas sensors, which were developed by our group, are quite promising to detect a low concentration of VOCs, because the VOCs, which are firstly adsorbed on the sensing materials at lower temperatures and then the adsorbed ones, are catalytically oxidized at pulsed heating to elevated temperatures leading to a large response to the VOCs. For example, the sensors using Pd-loaded mesoporous (mp-) alumina (Al2O3) exhibited excellent performance in detecting VOCs1), and co-loading of Au with Pd onto mp-Al2O3 by impregnation improved the sensing property to ethanol2). In addition, the ethanol-sensing property was further enhanced by highly dispersing Au(core)/Pd(shell) nanoparticles, which were prepared by ultrasonic-assisted reduction of Au and Pd chlorides with polyethylene glycol monostearate, on the mp-Al2O3 3). Recently, we have demonstrated that the loading of Pt nanoparticles on the mp-Al2O3 by utilizing the ultrasonic-assisted reduction is also effective in improving several VOCs such as ethanol, acetone, and ethyl acetate4). Therefore, VOC-sensing properties of adsorption/combustion-type micro gas sensors using mp-Al2O3 co-loaded with 1 wt% Pt and 10 wt% metal oxide (1Pt/10MO/mp-Al2O3 sensor, MO: metal oxide (Bi2O3, CeO2, Fe2O3, NiO, RuO2 or ZrO2)) have been investigated in this study. The mp-Al2O3 powder (specific surface area: ca. 250 m2 g-1) was prepared by microwave-assisted solvothermal treatment of Al(sec-OC4H9)3 in 1-propanol solution4). The 10 wt% MO-loaded mp-Al2O3 (10MO/mp-Al2O3) powders were prepared by impregnation with the constituent metal salt to the mp-Al2O3 powder, followed by firing at 700ºC for 1 h in air. Thereafter, the mp-Al2O3 and 10MO/mp-Al2O3 powders were loaded with 1.0 wt% Pt nanoparticles, which were synthesized by utilizing the ultrasonic-assisted reduction of H2PtCl6 (10 mM) in deionized water containing an appropriate amount of polyethylene glycol monostearate (MW: 4000). The obtained Pt-loaded powders (1 wt% Pt-loaded mp-Al2O3 (1Pt/mp-Al2O3) or 1 wt% Pt-loaded 10MO/mp-Al2O3 (1Pt/10MO/mp-Al2O3)) and mp-Al2O3 powder were set on the sensing and reference regions of a MEMS platform, respectively, and VOC-sensing properties of the adsorption/combustion-type micro gas sensors were measured with a mode of pulse-driven heating (high temperature (450°C) for 0.4 s after low temperature (150°C) for 9.6 s within a cycle of 10 s). In this operation mode, the target VOCs and/or the partially-decomposed products are adsorbed on the sensing materials at 150°C, and subsequently all the adsorbates abruptly burn upon the pulse heating up to 450°C. Thus, a sensor-signal profile typically consists of one large dynamic response and subsequent static response, which originate from the flash catalytic combustion of these adsorbates and general catalytic combustion, respectively, during the pulse heating at 450°C. The 1Pt/10CeO2-mp-Al2O3 sensor showed the largest static response to all target VOCs (ethanol, ethyl acetate, acetone, benzene, and toluene) among all the sensors tested, probably because Pt/10CeO2-mp-Al2O3 showed the largest specific surface area (ca. 187 m2 g-1). In addition, the magnitude of the static response was little dependent on the kinds of VOCs. On the other hand, all 1Pt/10MO/mp-Al2O3 sensors showed larger dynamic response to ethanol than other VOCs (ethyl acetate, acetone, benzene, and toluene). These sensors also showed relatively large dynamic responses to acetone and ethyl acetate, and the magnitude of dynamic responses to benzene and toluene was much smaller than that to acetone and ethyl acetate. Among them, the 1Pt/10CeO2-mp-Al2O3 sensor showed the largest dynamic response to most of target VOCs, while 1Pt/10Bi2O3-mp-Al2O3 showed the largest dynamic response to only toluene, even though the specific surface area of 1Pt/10Bi2O3-mp-Al2O3 (ca. 142 m2 g-1) is smaller than that of 1Pt/10CeO2-mp-Al2O3. Moreover, the dynamic response speed of the 1Pt/10Bi2O3-mp-Al2O3 sensor to toluene was faster than that of the 1Pt/10CeO2-mp-Al2O3 sensor. These toluene-sensing properties probably result from higher catalytic combustion behavior of toluene over 1Pt/10Bi2O3-mp-Al2O3 than 1Pt/10CeO2-mp-Al2O3. In addition, the adsorption property of toluene on 1Pt/10Bi2O3-mp-Al2O3 may also influence the dynamic response. 1. T. Sasahara, A. Kido, T. Sunayama, S. Uematsu, and M. Egashira, Sens. Actuators, 99, 532-538 (2004). 2. Y. Yuzuriha, T. Hyodo, T. Sasahara, Y. Shimizu, and M. Egashira, Sens. Lett, 9, 409-413 (2011) 3. T. Hyodo, Y. Yuzuriha, O. Nakagoe, T. Sasahara, S. Tanabe, and Y. Shimizu, Sens. Actuators, 202, 748-757 (2014). 4. T. Hyodo, T. Hashimoto, T. Ueda, O. Nakagoe, K. Kamada, T. Sasahara, S. Tanabe, and Y. Shimizy, Sens. Actuators, 220, 1091-1104 (2005).

VOCs transport with VOCs-adsorbing particles under VOCs emission from carpet

Many kinds of Volatile organic compounds (VOCs) emitted from building materials can deteriorate indoor air quality. Thus, it is essential to investigate how VOCs transport and how the airside VOCs concentration can be reduced. In order to remove airside VOCs, activated carbon particles can be used. This paper investigates the effect of activated carbon particles on the airside concentration of VOCs emitted from a new carpet in a room. A new numerical method for predicting airside VOCs concentration under the presence of activated carbon particles is developed, which includes spatially repeated iteration to get the transient airside VOCs concentration in association with the activated carbon particles’ adsorption of VOCs. The current numerical model is validated over an existing experimental result. Commercial software FLUENT 12.0 is adopted to solve the continuity, momentum, turbulence and concentration equations in two main cases under the situations with and without considering particle deposition. Numerical results show that the transient concentrations of VOCs in the air reach peaks, decay rapidly, drop slowly and remain in the room for a long time. When the particle concentration is at a higher level, the decrease in airside VOCs concentration is more notable. The concept proposed in this study can be utilized, with the use of activated carbon particles, to enhance the emission rate of VOCs in raw building materials before they are furnished in newly built indoor spaces.

Volatile organic compounds in polyethylene bags⿿A forensic perspective

Polyethylene bags, though not recommended, are sometimes used in some countries as improvised packaging for items sent to be analysed for the presence of volatile organic compounds, namely ignitable liquids residues. Sometimes items made of polyethylene constitute the samples themselves. It is well known what kind of volatile organic compounds are produced as a result of polyethylene thermal decomposition, but there is a lack of information relating to if some volatile compounds are present in unheated/unburned items made of polyethylene in detectable amounts and, if so, what those compounds are. The aim of this presented research was to answer these questions. 28 different bags made of polyethylene, representing 9 brands, were purchased in local shops and analysed according to the procedure routinely used for fire debris. The results proved that in almost all bags a distinctive mixture of compounds is present, comprising of n-alkanes and n-alkenes with an even number of carbon atoms in their molecules. Some other compounds (e.g., limonene, 2,2,4,6,6-pentamethylheptane) are also often present, but the presence of even n-alkanes and n-alkenes constitutes the most characteristic feature.

Synthesis of Co-doped SnO2 nanofibers and their enhanced gas-sensing properties

In this work, pure and 1–5mol% Co-doped SnO2 nanofibers were synthesized via an electrospinning method. The morphological and microstructural properties of these nanofibers were obviously changed and the grain size of the SnO2 nanocrystal were greatly decreased by Co doping. Sensors based on these nanofibers were fabricated after a hot pressing process on the ceramic plates. The gas-sensing properties of pure and Co-doped SnO2 nanofibers were tested to several kinds of Volatile Organic Compounds (VOCs). The results indicated that among all the samples (0, 1, 3 and 5mol% Co-doped SnO2 nanofibers), 3mol% Co-doped SnO2 nanofibers showed the highest response toward 100ppm ethanol, having a response of 40.1, which was over 4 times higher than pure SnO2 nanofibers. At the same time, the sensors based on 3mol% Co-doped SnO2 nanofibers also exhibited good repeatability and long term stability, which were promising for designing ethanol gas sensor with high performance.

Effects of immunological and hematological parameter in mice exposed to mixture of volatile organic compounds

Exposure to some kinds of volatile organic compounds (VOCs) leads to immune system disorders, liver and kidney damage, hematological change. However, there is little information about the effect of VOCs mixture on immune system and hematological parameter. In this study, 50 Kunming male mice were exposed in five similar chambers, 0 (control) and four different doses of VOCs mixture (G1–4) for consecutively 10 days at 2 h/day. The concentrations of VOCs mixture were as follows: formaldehyde, benzene, toluene and xylene 1.0 + 1.1 + 2.0 + 2.0, 3.0 + 3.3 + 6.0 + 6.0, 5.0 + 5.5 + 10.0 + 10.0 and 10.0 + 11.0 + 20.0 + 20.0 mg/m3, respectively, which corresponded to 10, 30, 50 and 100 times of indoor air quality standard in china. One day following VOCs exposure, spleen T lymphocyte subpopulation, serum biochemical markers and peripheral blood cells in mice were analyzed, respectively. VOCs exposure decreased significantly erythrocyte count (RBC), platelet (PLT) in peripheral blood in mice. While aspartate aminotransaminase (AST), alanine aminotransaminase (ALT), alkaline phosphatase (ALP) and creatinine (CREA) in serum increased significantly in G4 mice versus controls. Flow cytometry analysis showed that the number of splenic lymphocyte subpopulation cells decreased significantly in G2, 3 and 4 mice in comparison with normal Kunming mice. These results indicate inhalation of VOCs mixture affects CD4/8 subpopulations, liver, kidney function and some hematological parameters in mice.

Volatile organic compound emissions from an engine fueled with an ethanol-biodiesel-diesel blend

With the advent of energy crisis, vehicle engines need alternative energy sources eagerly to supply power. Ethanol-biodiesel-diesel blends are considered to be effective solutions. One way is diesel engines burning blended fuels. Diesel engines exhaust many kinds of volatile organic compounds (VOCs) when mixed fuels burn in them. Extremely poisonous as these VOCs are, they can cause severe damage to the natural environment as well as human health. To explore the characteristics of the unregulated emissions produced by diesel engines and then to limit them, research and studies should be conducted. The research in this paper used a single-cylinder diesel engine and a chromatograph mass spectrometer to investigate 9 kinds of VOCs (benzene, toluene, n-butyl acetate, ethylbenzene, p-xylene, m-xylene, styrene, o-xylene, n-undecane) emissions of ethanol-biodiesel-diesel (EBD) and diesel (D). The solid phase adsorption-thermal desorption-gas chromatography mass spectrometry (GC/MS) had an advantage in measuring and analyzing VOC emissions, so it was used for investigating the total emissions of 9 kinds of VOCs. Based on the standard curves of VOCs, the GC/MS computed the peak area of each VOC and realized the quantitative analysis of target compounds. By the calculating equation of VOC specific emissions and other test parameters (exhaust flow, engine power, dilution ratio, test time), the test got VOC specific emissions of two different fuels under different operating conditions. The test selected five typical conditions to collect exhaust when burning EBD and D. EBD contained 10 vol. % ethanol, 30 vol. % biodiesel, 55 vol. % diesel, 2.5 vol. % n-butyl alcohol and 2.5 vol. % iso-octyl alcohol, which had strong stabilities and good economy. From the analysis of the test results of VOC emissions, it was found that EBD increased total emissions by 84.2% at rated power but decreased by 14.85% at 10% load and by 20.39% at 50% load compared with diesel. But under other test conditions, VOC emissions with EBD were lower than diesel. VOC emissions of the two fuels were mainly benzene and toluene at medium and high load, which increased up to 47.4%. Emissions of other components increased at low load. In general, it was possible to decrease VOC emissions at medium or low loads when the diesel engine was fueled with EBD. The ozone specific reactivities (SR) of the engine exhaust for the two test fuels were approximately the same for the selected operating conditions. The SRs of EBD were a bit lower than D at medium and low loads. EBD had an advantage relative to VOC emissions which was found mainly at medium and low loads. This study is valuable for contributing to the building of a VOC emissions standard and for demonstrating the potential benefit of substitute fuels in reducing VOCs.

Decomposition of Toluene Using Nanosecond- Pulsed-Discharge Plasma Assisted With Catalysts

Volatile organic compounds (VOCs) are common air pollutants existing in various atmospheric environments; as they present both acute and chronic effects on the health of a number of different human systems and organs, methods for their efficient removal are essential. To this end, catalysis is being researched to prevent environmental pollution. While catalytic and photocatalytic oxidation, which can eliminate low concentrations of various kinds of VOCs as well as O3, offer potential to improve indoor air quality, neither is effective in areas with high VOC concentration. To overcome this limitation, many researchers have concentrated on synergetic effects of plasma catalysis, combining the advantages of high-selectivity catalysis and fast ignition and response of a nonthermal plasma. The authors’ research group has demonstrated that our nanosecond (ns)-pulsed-discharge plasma decomposes NO x as well as produces O3 with an energy efficiency higher than that of the reported nonthermal discharges. However, the performance of the ns-pulsed-discharge plasma in VOC decomposition in comparison with or without catalyst has not yet been investigated systematically. Thus, this paper experimentally clarified the combined effects of MnO x catalyst supported by Ni foam on toluene decomposition. The input energy density to our plasma catalysis reactor using a ns-pulsed discharge was 11% of a cited dielectric barrier discharge plasma catalysis when toluene removal ratio reached 100%.

Data Collecting and Identifying Based on Metalloporphyrin and Zinc Phthalocyanine Sensor Array

Smell-Seeing Sensor Array consists of two parts. One concerns a sensitive arrays, and the other deals with image collecting and processing technologies. In this paper, a 2×2 sensor array is made by the metalloporphyrin (CuTPP、ZnTPP、NiTPP) and zinc phthalocyanine (ZnPC). Exposed in vapor of 14 different kinds of VOCs (Volatile Organic Compounds) at room temperature, the array appears color change. ARM-Linux system and OpenCV are used to collect and process the color change. This system could detect 14 kinds of VOCs, achieving visualization of gas sensor detection, and laying a foundation of further qualitative identification of VOCs.

Using physical–chemical properties of reactants to estimate the performance of photocatalytic oxidation air cleaners

Various ultraviolet photocatalytic oxidation (UV–PCO) technologies are being used to eliminate or minimize different types of indoor air pollution, namely volatile organic compounds (VOCs). However, the removal efficiency of such air cleaning systems for different kind of VOCs could be challenging or completely unpredictable at different indoor environment conditions. This study presents a new systematic experimental method for measuring the performance of UV–PCO systems for different operational test conditions. The experiments were carried out using a continuous single pass system setup with three different types of TiO2 catalysts at high airflow rate and ambient indoor air temperature and humidity levels. The adsorption isotherm for each catalyst was determined individually to find a correlation for each test compounds. The relationship between the PCO rate constant and ionization potential (IP), as a physical and chemical property of selected alcohols compounds was investigated at the steady-state condition. The developed reaction rate correlations can be used as a design parameter to quantify the removal efficiency of other VOCs with the tested experimental system setup.

Assessment of steady state diffusion of volatile organic compounds in unsaturated building materials based on fractal diffusion model

This paper presents a preliminary work to evaluate the steady state diffusion of volatile organic compounds (VOCs) in unsaturated building materials based on a newly-proposed fractal diffusion model. This model studies the contributions of water and gas to the diffusion transportation in unsaturated building materials, involves geometry parameters of unsaturated building materials, fractal dimensions, minimal and maximal pore diameters. In this model, the derivation of some parameters is assisted by newly-established three phases fractal carpet consisting of middle and peripheral parts that represent gas and water occupied regions in the unsaturated building materials. The influences of some structural parameters (removed number, recursion number and size) of fractal carpet on diffusion performance have been discussed. Additionally, the effective diffusion coefficients of various kinds of volatile organic compounds (formaldehyde, methanol, 1,3,5-trimethylbenzene, Ethylbenzene, xylene isomers, benzene and toluene) are also compared based on this fractal model. Formaldehyde exhibits the largest value of effective diffusion coefficient among selected VOCs.

Sensor Based on Extracting Multidimensional Cataluminescence Signals for Idenpngying Toxic Gas

A sensor system for identifying toxic gas was fabricated by extracting multidimensional cataluminescence( CTL) signal based on two kinds of catalytic sensitive materials. Under the optimal conditions of wavelength of 440 nm,temperature of 247 ℃ and flow rate of 240 mL / min,eighteen kinds of volatile organic compounds respectively generated CTL signal I 1( the first order reaction signal) when each vapor passed through nano-Al2O3 or MgO,then residual gas from first reaction was regarded as a new reactant and continued to be oxidized on nano-Al2O3 or MgO,generating new CTL signal I 2( the second order reaction signal). Moreover, for each organic gas,eight CTL signals could be obtained by changing the direction of the gas flowing through Al2O3-MgO,which formed the characteristic spectrum for each toxic compound. Different gases could be scientifically and objectively identified based on the principal component analysis( PCA). In addition,linear discriminant analysis( LDA) was utilized to identify eighteen kinds of organic gas in different concentration( 100,300 and 500 mL/m3) with an accuracy of 100%. Furthermore,the sensor could achieve quantitative analysis with the detection limits below the occupational exposure limit of workplace( GBZ2. 1-2007). Several kinds of common pollutants in the air had no interference on the detection of chosen toxic gases. Therefore, the sensor system may be capable to develop a micro-sensor with less sensing elements,good stability,convenient operation,rich information and strong recognition ability in real-life application.

Sector instruments for chemical analysis and research

When the last chemical elements were successfully measured by mass spectrometry its use for the characterisation of isotopes declined, but its use for chemical analysis and research grew. This new field of activity was aided by the emergence of commercially manufactured sector mass spectrometers designed for the analysis of oil refinery gases. Although the 1940s saw the use of mass spectrometry dominated by the petroleum industry it also saw many developments in its application to chemical analysis. By the early 1950s heated inlet systems were allowing spectra of all kinds of volatile organic compounds to be obtained. The 1950s saw the development of accurate mass measurement of organic molecules as a means of determining their elemental composition. This led to a demand for higher resolution double focusing instruments. Two types of design competed for this application, each with their perceived advantages and disadvantages. It was another decade, following the application of computers to high throughput accurate mass measurement, before one of these came to dominate. Double focusing sector instruments also enhance the information afforded by “metastable” ions, allowing identification of precursor and product ions. This led to the developments of Collision Induced Decompositions, MIKES and “linked scans”. The mass range demanded of mass spectrometers jumped to new levels with the development of Fast Atom Bombardment (FAB). This led to new sector designs incorporating innovative new magnets. The success of FAB as a soft ionisation technique meant it produced little fragmentation and structural information. This led to a growth in the use of tandem MS/MS instrumentation as a tool for determining structures. This paper recounts these and many other developments which kept magnetic sectors at the centre of major new developments in mass spectrometry for chemical analysis and research for so long.

The Method Study on Emergency Detection of Aromatic Compounds and Chlorides based on Portable GC-MS

In order to quickly identify the kinds of volatile organic compounds(VOCs) and quantified their concentrations, a method based on portable GC−MS was developed, which was especially suitable for the detection of aromatic compounds and chlorides. The mixed gases were directly collected by solid phase microextraction head for 120seconds. After that, they were analyzed on the portable GC-MS, identified by retention time and MS peaks, quantified by external standard method. It only took 6.4min from sampling to get the result. The linear correlation was larger than 0.98, and the minimum detectable concentration was lower than half of their occupational exposure limits, respectively. In the simulation test, the relative error was lower than 4.4%. This method can directly collect the air sample in the field, rarely depends on external conditions, and is very convenient to carry out. It takes very short time to complete the detection, at the same time it can identify and quantify multiple kinds of gases at a time. So this method is quite suitable for the emergency detection at the gas leak site.

Effects of subchronic exposure to low‐dose volatile organic compounds on lung inflammation in mice

Inflammatory lung diseases are characterized by chronic inflammation and oxidant/antioxidant imbalance. Exposure to some kinds of volatile organic compounds (VOCs) leads to lung inflammation, oxidative stress, and immune modulation. However, it is suspected that sub-chronic exposure to low-dose VOCs mixture induces or aggravates lung inflammation. To clarify the effect of this exposure on lung inflammatory responses, 40 male Kunming mice were exposed in four similar static chambers, 0 (control) and three different doses of VOCs mixture (groups 1-3). The concentrations of VOCs mixture were as follows: formaldehyde, benzene, toluene, and xylene 0.10 + 0.11 + 0.20 + 0.20 mg/m(3) , 0.50 + 0.55 + 1.00 + 1.00 mg/m(3) , 1.00 + 1.10 + 2.00 + 2.00 mg/m(3) , respectively, which corresponded to 1, 5, and 10 times of indoor air quality standard in China. After 90 consecutive days of exposure (2 h/day), oxidative stress markers in lung, cellular infiltration and cytokines, chemokine, neurotrophin in bronchoalveolar lavage fluid (BALF), and immunoglobulin (Ig) in serum were examined. VOCs exposure could increase significantly reactive oxygen species (ROS) in lung, the levels of interleukin-8 (IL-8), IL-4, eotaxin, nerve growth factor (NGF), and various types of leukocytes in BALF, IgE concentration in serum. In contrast, GSH to GSSG ratio and interferon-gamma were significantly decreased following the VOCs exposure. These results indicate that the VOCs mixture-induced inflammatory response is at least partly caused by release of the ROS and mediators from the activated eosinophils, neutrophils, alveolar macrophages and epithelial cells.