Range Of Volatile Organic Compounds Research Articles

Measurements of Activity Coefficients at Infinite Dilution for Organic Solutes in the Ionic Liquids N-Ethyl- and N-Octyl-N-methylmorpholinium Bis(trifluoromethanesulfonyl)imide. A Useful Tool for Solvent Selection.

In recent years, many papers describing ionic liquids (IL) as promising solvents in separation techniques have been published. The conscious choice of appropriate ionic liquid as absorption media in effective extraction of selected types of analytes requires deeper understanding of the analyte−IL interactions. Therefore, intensive research is conducted to determine the values of activity coefficient at infinite dilution, which allows us to characterize the nature of these interactions. Based on the inverse gas chromatography retention data, activity coefficients at infinite dilution of 48 different organic compounds in the ionic liquids N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide [C2C1Mor][TFSI] and N-octyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide [C8C1Mor][TFSI] were determined. The measurements covered a broad range of volatile organic compounds, including n-alkanes, n-alkenes, n-alkynes, alcohols, aldehydes, ketones, aromatic compounds and common polar solvents, representing different types of interactions. Activity coefficients at infinite dilution were measured in the temperature range from 313.15 to 363.15 K. The excess partial molar enthalpies and entropies at infinite dilution were determined. Selectivity at infinite dilution was also calculated for exemplary separation processes in the hexane/benzene system. The obtained results were analyzed and compared with literature data for ionic liquids containing the same anion [TFSI]¯ and different cations. The study results indicate that some potential applications of the investigated ionic liquids in separation problems exist.

Volatile Organic Compounds Profile Obtained from Processing Steps of Pacific Oysters (Crassostrea gigas) as Perspective for Food Industry

ABSTRACTIn the heat treatment of oysters, many aroma compounds are lost in the cooking steam and water. In this study, aroma compound profiles from oyster processing were identified by gas chromatography- mass spectrometry (GC-MS). The compounds were extracted by headspace-solid phase microextraction (HS-SPME), while the best process conditions such as temperature, extraction time, and desorption time were studied. The aroma compounds were obtained from raw oysters, from oysters after thermal treatment, from water released from raw oysters, from cooking steam, and from oyster boiling juice. All compounds were identified and semi-quantified by GC-MS. The major oyster aroma compounds were 1-octen-3-ol, hexanal, and benzaldehyde. Most of the components from oysters were lost both to the cooking steam and to the oyster boiling juice. The concentration range of volatile organic compounds transferred for oyster boiling juice between 14 and 90 mg L−1 shows that the residues from oyster processing have great technological potential, and they can be recovered for application as aromas by the food industry.

Evaluating air quality with and without air fresheners

Air fresheners emit a range of volatile organic compounds, which can include hazardous air pollutants. Exposure to air fresheners has been associated with health problems such as migraine headaches, respiratory difficulties, and asthma attacks. To reduce pollutant exposures and potential adverse effects, air fresheners can be discontinued from use within indoor environments. However, little is known about how much air quality can be improved and over what time. This study evaluates the effects of air fresheners on air quality with a focus on d-limonene, a prevalent and dominant compound in air fresheners and one that can generate hazardous air pollutants. Using workplace environments, the study analyses and compares d-limonene concentrations in restrooms that use air fresheners, that discontinue the use of air fresheners, and that do not use air fresheners. In restrooms that use air fresheners, d-limonene concentrations averaged 6.78 μg/m3 compared with 0.84 μg/m3 in restrooms that do not use air fresheners. Further, after discontinuing the use of air fresheners, d-limonene concentrations decreased up to 96% within 2 weeks with an average reduction of 81% and an average concentration down to 1.17 μg/m3. These findings suggest that a straightforward strategy, such as ceasing the use of air fresheners, can produce measurable benefits for indoor air quality.

Liquid–liquid phase separation and viscosity within secondary organic aerosol generated from diesel fuel vapors

Abstract. Information on liquid–liquid phase separation (LLPS) and viscosity (or diffusion) within secondary organic aerosol (SOA) is needed to improve predictions of particle size, mass, reactivity, and cloud nucleating properties in the atmosphere. Here we report on LLPS and viscosities within SOA generated by the photooxidation of diesel fuel vapors. Diesel fuel contains a wide range of volatile organic compounds, and SOA generated by the photooxidation of diesel fuel vapors may be a good proxy for SOA from anthropogenic emissions. In our experiments, LLPS occurred over the relative humidity (RH) range of ∼70 % to ∼100 %, resulting in an organic-rich outer phase and a water-rich inner phase. These results may have implications for predicting the cloud nucleating properties of anthropogenic SOA since the presence of an organic-rich outer phase at high-RH values can lower the supersaturation with respect to water required for cloud droplet formation. At ≤10 % RH, the viscosity was ≥1×108 Pa s, which corresponds to roughly the viscosity of tar pitch. At 38 %–50 % RH, the viscosity was in the range of 1×108 to 3×105 Pa s. These measured viscosities are consistent with predictions based on oxygen to carbon elemental ratio (O:C) and molar mass as well as predictions based on the number of carbon, hydrogen, and oxygen atoms. Based on the measured viscosities and the Stokes–Einstein relation, at ≤10 % RH diffusion coefficients of organics within diesel fuel SOA is ≤5.4×10-17 cm2 s−1 and the mixing time of organics within 200 nm diesel fuel SOA particles (τmixing) is 50 h. These small diffusion coefficients and large mixing times may be important in laboratory experiments, where SOA is often generated and studied using low-RH conditions and on timescales of minutes to hours. At 38 %–50 % RH, the calculated organic diffusion coefficients are in the range of 5.4×10-17 to 1.8×10-13 cm2 s−1 and calculated τmixing values are in the range of ∼0.01 h to ∼50 h. These values provide important constraints for the physicochemical properties of anthropogenic SOA.

Development of a method based on thermal desorption-gas chromatography/mass spectrometry for the determination of 103 volatile organic compounds in mattresses

ABSTRACT A sensitive and reliable method based on environment test chamber coupled with thermal desorption and gas chromatography-mass spectrometry (ETC-TD-GC/MS) was developed and validated for the determination of 103 volatile organic compounds (VOCs) emitted from mattresses. In the study, two commercial sorbent tubes were compared in terms of adsorption efficiency towards the target analytes. The result illustrated that the multisorbent tubes containing Carbopack C, Carbopack B and Carboxen 1000 had better performance than Tenax TA tubes owing to their large surface area, low capacity for water and high temperature stability, which allowed a wide range of VOCs to be absorbed, especially for VOCs with low boiling points and small molecules. To achieve the optimum conditions for the analysis, several thermal desportion parameters were accurately investigated. Under the optimal conditions, the method showed good linearities, with correlation coefficients ranging from 0.9982 to 0.9999 and the method detection limits and method quantification limitsfor target compounds in the range of 0.006 ~ 0.561 µg/m3 and 0.020 ~ 1.870 µg/m3, respectively. In order to evaluate the performance of the developed method on real samples, various mattresses from different manufacturers were analysed. All mattress samples were found to emit VOCs and the values of area-specific emission rate (SERs) for total target compounds were in the range of 90.25 ~ 288.63 µg/m2·h. Moreover, the SERs of VOCs were influenced by the type of sponge materials and mattress fabric layers. The study demonstrated that the method is sensitive, accurate and well-suited for the determination of VOCs emitted from mattresses.

Peroxy radical measurements by ethane – nitric oxide chemical amplification and laser-induced fluorescence during the IRRONIC field campaign in a forest in Indiana

Abstract. Peroxy radicals were measured in a mixed deciduous forest atmosphere in Bloomington, Indiana, USA, during the Indiana Radical, Reactivity and Ozone Production Intercomparison (IRRONIC) during the summer of 2015. Total peroxy radicals ([XO2]≡[HO2]+Σ[RO2]) were measured by a newly developed technique involving chemical amplification using nitric oxide (NO) and ethane (C2H6) followed by NO2 detection by cavity-attenuated phase-shift spectroscopy (hereinafter referred to as ECHAMP – Ethane CHemical AMPlifier). The sum of hydroperoxy radicals (HO2) and a portion of organic peroxy radicals ([HO2*]=[HO2]+Σαi[RiO2], 0<α<1) was measured by the Indiana University (IU) laser-induced fluorescence–fluorescence assay by gas expansion instrument (LIF-FAGE). Additional collocated measurements include concentrations of NO, NO2, O3, and a wide range of volatile organic compounds (VOCs) and meteorological parameters. XO2 concentrations measured by ECHAMP peaked between 13:00 and 16:00 local time (LT), with campaign average concentrations of 41±15 ppt (1σ) at 14:00 LT. Daytime concentrations of isoprene averaged 3.6±1.9 ppb (1σ), whereas average concentrations of NOx ([NO] + [NO2]) and toluene were 1.2 and 0.1 ppb, respectively, indicating a low impact from anthropogenic emissions at this site. We compared ambient measurements from both instruments and conducted a calibration source comparison. For the calibration comparison, the ECHAMP instrument, which is primarily calibrated with an acetone photolysis method, sampled the output of the LIF-FAGE calibration source which is based on the water vapor photolysis method and, for these comparisons, generated a 50 %–50 % mixture of HO2 and either butane or isoprene-derived RO2. A bivariate fit of the data yields the relation [XO2]ECHAMP=(0.88±0.02;[HO2]+[RO2])IU_cal+(6.6±4.5) ppt. This level of agreement is within the combined analytical uncertainties for the two instruments' calibration methods. A linear fit of the daytime (09:00–22:00 LT) 30 min averaged [XO2] ambient data with the 1 min averaged [HO2*] data (one point per 30 min) yields the relation [XO2]=(1.08±0.05)[HO2*]-(1.4±0.3). Day-to-day variability in the [XO2]/[HO2*] ratio was observed. The lowest [XO2]/[HO2*] ratios between 13:00 and 16:00 LT were 0.8 on 13 and 18 July, whereas the highest ratios of 1.1 to 1.3 were observed on 24 and 25 July – the same 2 d on which the highest concentrations of isoprene and ozone were observed. Although the exact composition of the peroxy radicals during IRRONIC is not known, zero-dimensional photochemical modeling of the IRRONIC dataset using two versions of the Regional Atmospheric Chemistry Mechanism (RACM2 and RACM2-LIM1) and the Master Chemical Mechanism (MCM 3.2 and MCM 3.3.1) all predict afternoon [XO2]/[HO2*] ratios of between 1.2 and 1.5. Differences between the observed ambient [XO2]/[HO2*] ratio and that predicted with the 0-D modeling can be attributed to deficiencies in the model, errors in one of the two measurement techniques, or both. Time periods in which the ambient ratio was less than 1 are definitely caused by measurement errors (including calibration differences), as such ratios are not physically meaningful. Although these comparison results are encouraging and demonstrate the viability in using the new ECHAMP technique for field measurements of peroxy radicals, further research investigating the overall accuracy of the measurements and possible interferences from both methods is warranted.

Segmented flow coil equilibrator coupled to a proton-transfer-reaction mass spectrometer for measurements of a broad range of volatile organic compounds in seawater

Abstract. We present a technique that utilises a segmented flow coil equilibrator coupled to a proton-transfer-reaction mass spectrometer to measure a broad range of dissolved volatile organic compounds. Thanks to its relatively large surface area for gas exchange, small internal volume, and smooth headspace–water separation, the equilibrator is highly efficient for gas exchange and has a fast response time (under 1 min). The system allows for both continuous and discrete measurements of volatile organic compounds in seawater due to its low sample water flow (100 cm3 min−1) and the ease of changing sample intake. The equilibrator setup is both relatively inexpensive and compact. Hence, it can be easily reproduced and installed on a variety of oceanic platforms, particularly where space is limited. The internal area of the equilibrator is smooth and unreactive. Thus, the segmented flow coil equilibrator is expected to be less sensitive to biofouling and easier to clean than membrane-based equilibration systems. The equilibrator described here fully equilibrates for gases that are similarly soluble or more soluble than toluene and can easily be modified to fully equilibrate for even less soluble gases. The method has been successfully deployed in the Canadian Arctic. Some example data from underway surface water and Niskin bottle measurements in the sea ice zone are presented to illustrate the efficacy of this measurement system.

Biological effect of VOCs produced during Pseudomonas syringae pv. actinidiae infection of kiwifruit plant

A wide range of volatile organic compounds (VOCs) is released during plant-pathogen interactions both by the pathogens and the hosts. Some of these VOCs may have an effect on plant signal transduction pathways, thus contributing to pathogenicity or plant defense responses. Strains of the virulent biovar 3 of Pseudomonas syringae pv. actinidiae emit ethylene, both from axenic cultures in a growth medium obtained from Actinidia deliciosa leaf extract, and from infected plants. Accordingly, the infection stimulates the ethylene signal cascade in the host. Other compounds, either emitted by the bacterium (such as 1-undecene, linear ketones and benzyl alcohol), or strongly induced in plants after infection, such as decane, may present a biological activity. Healthy plants react to VOCs from infected neighbors, by activating the phenylpropanoid pathway and several PR genes. However, after the infection, P. syringae pv. actinidiae is able to selectively depress the induced plant defenses, possibly by stimulating the oxylipin pathway. Ethylene and oxylipin derivatives, such as jasmonates, may counteract salicylic acid-mediated defenses, thus allowing bacterial growth in the host plant. Our research demonstrates that VOCs from infected plants may promote both plant defenses and disease development. The further characterization of the signaling pathways involved in such mechanisms may result useful to design plant protection strategies.

A wide range sensor of a 3D mesoporous silica coated QCM electrodes for the detection of volatile organic compounds

A quartz crystal microbalance (QCM) electrode coated with high surface area mesoporous silica KIT-6 films was designed as a sensor for the detection of a wide range of volatile organic compounds (VOCs) such as aliphatic alcohols, aliphatic amines, benzene and toluene at room temperature. A thin film of KIT-6 coating on Au-electrode of QCM was prepared by a simple drop-coating approach. The mesoporous silica KIT-6 was characterized with transmission electron microscope (TEM), low-angle X-ray difraction (XRD), Fourier transform infrared spectrocsopy (FT-IR) and N2 sorption isotherm. The frequency shifts (Δf) of the QCM coated with mesoporous silica KIT-6 films were measured as a function of time after injection of different VOCs vapors. Δfs were found to be increased linearly with the injected chemical vapor concentration. The results definitely showed an enhanced detection sensitivity and a fast response of the QCM sensor. The sensor showed an unusual high sensitivity and selectivity for amine compounds and the equilibrium was achieved within few seconds. The adsorption kinetics and relaxation time of methanol and ethanol vapors were carefully studied.

Vehicle interior air quality conditions when travelling by taxi

Vehicle interior air quality (VIAQ) was investigated inside 14 diesel/non-diesel taxi pairs operating simultaneously and under normal working conditions over six weekday hours (10.00–16.00) in the city of Barcelona, Spain. Parameters measured included PM10 mass and inorganic chemistry, ultrafine particle number (N) and size, lung surface deposited area (LDSA), black carbon (BC), CO2, CO, and a range of volatile organic compounds (VOCs). Most taxi drivers elected to drive with windows open, thus keeping levels of CO2 and internally-generated VOCs low but exposing them to high levels of traffic-related air pollutants entering from outside and confirming that air exchange rates are the dominant influence on VIAQ. Median values of N and LDSA (both sensitive markers of VIAQ fluctuations and likely health effects) were reduced to around 104 #/cm3 and < 20 µm2/cm3 respectively under closed conditions, but more than doubled with windows open and sometimes approached 105 #/cm3 and 240 µm2/cm3. In exceptional traffic conditions, transient pollution peaks caused by outside infiltration exceeded N = 106 #/cm3 and LDSA= 1000 µm2/cm3. Indications of self-pollution were implicated by higher BC and CO levels, and larger UFP sizes, measured inside diesel taxis as compared to their non-diesel pair, and the highest concentrations of CO (>2 ppm) were commonly associated with older, high-km diesel taxis. Median PM10 concentrations (67 µg/m3) were treble those of urban background, mainly due to increased levels of organic and elemental carbon, with source apportionment calculations identifying the main pollutants as vehicle exhaust and non-exhaust particles. Enhancements in PM10 concentrations of Cr, Cu, Sn, Sb, and a “High Field Strength Element” zircon-related group characterised by Zr, Hf, Nb, Y and U, are attributed mainly to the presence of brake-derived PM. Volatile organic compounds display a mixture which reflects the complexity of traffic-related organic carbon emissions infiltrating the taxi interior, with 2-methylbutane and n-pentane being the most abundant VOCs, followed by toluene, m-xylene, o-xylene, 1,2,4-trimethylbenzene, ethylbenzene, p-xylene, benzene, and 1,3,5-trimethylbenzene. Internally sourced VOCs included high monoterpene concentrations from an air freshener, and interior off-gassing may explain why the youngest taxi registered the highest content of alkanes and aromatic compounds. Carbon dioxide concentrations quickly climbed to undesirable levels (>2500 ppm) under closed ventilation conditions and could stay high for much of the working day. Taxi drivers face daily occupational exposure to traffic-related air pollutants and would benefit from a greater awareness of VIAQ issues, notably the use of ventilation, to encourage them to minimise possible health effects caused by their working environment.

Elucidation of headspace volatilome in Polianthes tuberosa flower for identifying non-invasive biomarkers

To date, no volatilome study has used the dynamic headspace method, based on adsorption–desorption principle, to investigate the chemical divergence of floral fragrance in Polianthes tuberosa L. (cv. Calcutta Single). This study proposes a suitable adsorbent/solvent combination to analyze emitted volatiles from this flower, allowing for a qualitative, and tentatively quantitative, floral volatilome using a holistic approach. Here, 13 different adsorbent/solvent combinations were used to determine the total emitted volatilome, from in situ and plucked flowers, using headspace and gas chromatography–mass spectrometry. Several adsorbent/solvent combinations were explored to optimize trapping the most diverse range of volatile organic compounds in a single attempt. A mixture of porous polymers (Porapak or Tenax) with graphite or charcoal were best when combined with dichloromethane as the eluting solvent. Among the two solvents, dichloromethane showed better desorption efficiency than hexane. For better elucidation of any specific chemical group, suitable adsorbent and solvent should be chosen properly or the quantity or quality of the volatilome captured would be compromised. Three distinct classes of volatile organic compounds were categorized: aromatics, terpenes, and fatty acid derivatives. Maximum diversity, along with quantity, was found with the aromatic group. Total chemical divergence of volatilome from in situ and freshly plucked flowers was similar. Benzyl salicylate, methyl 2-amino benzoate, germacrene D, farnesal, farnesyl acetate, and delta decalactone may be considered biomarkers for the origin of P. tuberosa floral scent.

Purification of model biogas from toluene using deep eutectic solvents

Biogas from landfills and wastewater treatment facilities typically contain a wide range of volatile organic compounds (VOCs), that can cause severe operational problems when biogas is used as fuel. Among the contaminants commonly occur aromatic compounds, i.e. benzene, ethylbenzene, toluene and xylenes (BTEX). In order to remove BTEX from biogas, different processes can be used. A promising process for VOCs removal is their absorption in deep eutectic solvents (DES). In this work, three DES: ([ChCl] U TEG [choline chloride]:urea:tetraethylene glycol (1:2:2), [ChCl] U [choline chloride]:urea (1:2), [ChCl] DEG [choline chloride]:diethylene glycol (1:2)) and water were tested to toluene absorption in concentration of 2000 ppm v/v in nitrogen stream. The results demonstrated the high absorption capacity of toluene using DES based on glycols.

Emissions from dryer vents during use of fragranced and fragrance-free laundry products

Fragranced laundry products emit a range of volatile organic compounds, including hazardous air pollutants. Exposure to fragranced emissions from laundry products has been associated with adverse health effects such as asthma attacks and migraine headaches. Little is known about volatile emissions from clothes dryer vents and the effectiveness of strategies to reduce concentrations and risks. This study investigates volatile emissions from six residential dryer vents, with a focus on d-limonene. It analyses and compares concentrations of d-limonene during use of fragranced and fragrance-free laundry products, as well as changes in switching from fragranced to fragrance-free products. In households using fragranced laundry detergent, the highest concentration of d-limonene from a dryer vent was 118 μg/m3 (mean 33.34 μg/m3). By contrast, in households using only fragrance-free detergent, the highest concentration of d-limonene from a dryer vent was 0.26 μg/m3 (mean 0.25 μg/m3). After households using fragranced detergent switched to using fragrance-free detergent, the concentrations of d-limonene in dryer vent emissions were reduced by up to 99.7% (mean 79.1%). This simple strategy of switching to fragrance-free products significantly and almost completely eliminated d-limonene emissions. Results from this study demonstrate that changing from fragranced to fragrance-free products can be a straightforward and effective approach to reduce ambient air pollution and potential health risks.

A Hybrid Reactor System Comprised of Non-Thermal Plasma and Mn/Natural Zeolite for the Removal of Acetaldehyde from Food Waste

The degradation of low concentrations of acetaldehyde while using a non-thermal plasma (NTP)/catalyst hybrid reactor system was investigated while using humidified air at ambient temperature. A series of highly active manganese-impregnated natural zeolite (Mn/NZ) catalysts were synthesized by the incipient wetness method using sonication. The Mn/NZ catalysts were analyzed by Brunauer-Emmett-Teller surface area measurements and X-ray photoelectron spectroscopy. The Mn/NZ catalyst located at the downstream of a dc corona was used for the decomposition of ozone and acetaldehyde. The decomposition efficiency of ozone and acetaldehyde was increased significantly using the Mn/NZ catalyst with NTP. Among the various types of Mn/NZ catalysts with different Mn contents, the 10 wt.% Mn/NZ catalyst under the NTP resulted the highest ozone and acetaldehyde removal efficiency, almost 100% within 5 min. Moreover, this high efficiency was maintained for 15 h. The main reason for the high catalytic activity and stability was attributed to the high dispersion of Mn on the NZ made by the appropriate impregnation method using sonication. This system is expected to be efficient to decompose a wide range of volatile organic compounds with low concentrations.

A Chemical Alphabet for Macromolecular Communications.

Molecular communications in macroscale environments is an emerging field of study driven by the intriguing prospect of sending coded information over olfactory networks. For the first time, this article reports two signal modulation techniques (on-off keying-OOK, and concentration shift keying-CSK) which have been used to encode and transmit digital information using odors over distances of 1-4 m. Molecular transmission of digital data was experimentally investigated for the letter "r" with a binary value of 01110010 (ASCII) for a gas stream network channel (up to 4 m) using mass spectrometry (MS) as the main detection-decoding system. The generation and modulation of the chemical signals was achieved using an automated odor emitter (OE) which is based on the controlled evaporation of a chemical analyte and its diffusion into a carrier gas stream. The chemical signals produced propagate within a confined channel to reach the demodulator-MS. Experiments were undertaken for a range of volatile organic compounds (VOCs) with different diffusion coefficient values in air at ambient conditions. Representative compounds investigated include acetone, cyclopentane, and n-hexane. For the first time, the binary code ASCII (American Standard Code for Information Interchange) is combined with chemical signaling to generate a molecular representation of the English alphabet. Transmission experiments of fixed-width molecular signals corresponding to letters of the alphabet over varying distances are shown. A binary message corresponding to the word "ion" was synthesized using chemical signals and transmitted within a physical channel over a distance of 2 m.

Mass transfer inside a flux hood for the sampling of gaseous emissions from liquid surfaces – Experimental assessment and emission rate rescaling

This study assesses the mass transfer of compounds inside the US EPA flux hood, one of the enclosure devices most commonly employed for the direct measurement of atmospheric emissions from liquid surfaces in wastewater treatment plants (WWTPs). Experiments comprised the evaporation of water and the volatilisation of a range of volatile organic compounds (VOCs). Special attention was given to the evaluation of the mass transfer coefficients in the microenvironment created by the flux hood and the effects of concentration build up in the hood's headspace. The VOCs emission rates and the water evaporation rates generally increased with the sweep air flow rate, as did the mass transfer coefficients for all compounds. The emission of compounds whose volatilisation is significantly influenced by the gas phase was greatly affected by concentration build up, whereas this effect was not significant for liquid phase-controlled compounds. The gas-film mass transfer coefficient (kG) estimated inside the US EPA flux hood was of the same order as the respective kG reported in the literature for wind tunnel-type devices, but the emission rates measured by the flux hood can be expected to be lower, due to the concentration build-up. Compared against an emission model for the passive surfaces in WWTPs, the mass transfer of acetic acid (representing a gas phase-dominated compound) inside the US EPA flux hood was equivalent to conditions of wind speeds at 10 m height (U10) of 0.27, 0.51 and 0.99 m s−1, respectively, for sweep air flow rates of 2, 5 and 10 L min−1. On the other hand, for higher wind speeds, the emission rates of gas phase-controlled compounds obtained with the flux hood can be considerably underestimated: for instance, at U10 = 5 m s−1, the emission rates of acetic acid inside the flux hood would be approximately 23, 12 and 6 times lower than the emission rates in the field, for sweep air flow rates of 2, 5 and 10 L min−1, respectively. A procedure is presented in order to scale the emission rates of these compounds measured with the flux hood to field conditions of higher winds.

Acquisition of Volatile Compounds by Gas Chromatography-Mass Spectrometry (GC-MS).

Plants synthesize and emit a large range of volatile organic compounds (VOCs) that play important roles in their interactions with the environment, from attracting pollinators and seed dispersers to protectants such as repellants and pathogen inhibitors. As such, the development of techniques for headspace collection of volatiles in combination with gas chromatography-mass spectrometry (GC-MS) has an important impact on our understanding of the biosynthesis of plant VOCs. Furthermore, knowledge of the plant VOCs can be valuable in relation to plant breeding for improving fruit flavor or enhancing resistance to insects or pathogens. This chapter describes a reliable method for extracting volatile compounds by headspace solid-phase microextraction (HS-SPME), and separate and detect them by GC-MS.

Secondary organic aerosol from chlorine-initiated oxidation of isoprene

Abstract. Recent studies have found concentrations of reactive chlorine species to be higher than expected, suggesting that atmospheric chlorine chemistry is more extensive than previously thought. Chlorine radicals can interact with hydroperoxy (HOx) radicals and nitrogen oxides (NOx) to alter the oxidative capacity of the atmosphere. They are known to rapidly oxidize a wide range of volatile organic compounds (VOCs) found in the atmosphere, yet little is known about secondary organic aerosol (SOA) formation from chlorine-initiated photooxidation and its atmospheric implications. Environmental chamber experiments were carried out under low-NOx conditions with isoprene and chlorine as primary VOC and oxidant sources. Upon complete isoprene consumption, observed SOA yields ranged from 7 to 36 %, decreasing with extended photooxidation and SOA aging. Formation of particulate organochloride was observed. A high-resolution time-of-flight chemical ionization mass spectrometer was used to determine the molecular composition of gas-phase species using iodide–water and hydronium–water cluster ionization. Multi-generational chemistry was observed, including ions consistent with hydroperoxides, chloroalkyl hydroperoxides, isoprene-derived epoxydiol (IEPOX), and hypochlorous acid (HOCl), evident of secondary OH production and resulting chemistry from Cl-initiated reactions. This is the first reported study of SOA formation from chlorine-initiated oxidation of isoprene. Results suggest that tropospheric chlorine chemistry could contribute significantly to organic aerosol loading.

Molecular Communication over Gas Stream Channels using Portable Mass Spectrometry.

The synthetic generation/coding and transmission of olfactory information over a gas stream or an odor network is a new and unexplored field. Application areas vary from the entertainment or advertisement industry to security and telemedicine. However, current technological limitations frustrate the accurate reproduction of decoded and transmitted olfactory data. This study describes the development, testing, and characterization of a novel odor emitter (OE) that is used to investigate the generation-encoding of gaseous standards with odorous characteristics with a regulatable way, for scent transmission purposes. The calibration and the responses of a developed OE were examined using a portable quadrupole mass spectrometer (MS). Experiments were undertaken for a range of volatile organic compounds (VOCs) at different temperatures and flow rates. Individual compounds and mixtures were tested to investigate periodic and dynamic transmission characteristics within two different size tubular containers for distances up to 3 m. Olfactory information transmission is demonstrated using MS as the main molecular sensor for odor detection and monitoring and for the first time spatial encryption of olfactory information is shown. Graphical Abstract ᅟ.

Abstract 204: In vitro metabolomics of mesothelioma: Challenges and outcomes

Abstract Introduction Early detection of malignant pleural mesothelioma (MPM) is likely to improve outcome in affected patients. From our previous studies (MesoBreath 1 &amp; 2) we developed a screening tool in which volatile organic compounds (VOCs) in breath allowed discrimination of MPM patients from at risk controls. However it is not yet clear which VOCs arise from the neoplastic cells themselves or from the host response. Identifying the cancer cell-specific compounds should increase the specificity of our breathomic signature model. Therefore, we set up an in vitro experimental setup model for VOC analysis from the headspace of mesothelioma cell lines. Methods Standard polystyrene culture flasks (NunclonTM Delta Surface, Thermo Scientific) were mounted with an adapted cap accommodating teflon inlet and outlet tubes. The inlet tube provides environmental air while an external pump (Gilian GilAir Plus, Sensidyne) draws headspace air from the outlet tube over an adsorption column (Tenax GR, Markes International, UK). The adsorption columns were further processed on a GC-MS platform (GC: Focus GC, Thermo Finnigan, Milan, Italy; DSQII Single Quadrupole MS, Thermo Finnigan, Austin, TX, USA). VOC profiles were processed using supervised clustering algorithms and principal component analysis. Results Using this setup, we have investigated the impact of flow and total sampled volume on the concentration and range of VOCs detected. For a constant flow, VOCs were detected in higher concentrations with increasing sample volume. For a constant volume, a lower sampling flow yielded a higher concentration of detected VOCs. Most of the VOCs obtained were alkanes and ketones. We will show data illustrating the differential VOC profiles of container plastic, cell culture medium and growing mesothelioma cancer cells, as well as the differential VOC output of epithelioid vs sarcomatoid mesothelioma cell lines. Conclusions We have succesfully developed an in vitro experimental setup allowing collection and analysis of VOCs emanating from mesothelioma cancer cell line cultures. This platform will allow us to investigate how VOC profiles are impacted in different experimental conditions (e.g. hypoxia, nutrient deprivation, cytostatics, co-culture with leukocytes). The data collected will help us to pinpoint the cancer cell-derived VOCs from patient exhaled breath, and increase the robustness of our mesothelioma breathomic signature. Note: This abstract was not presented at the meeting. Citation Format: Sabrina Lagniau, Kevin Lamote, Lore Vandermeersch, Herman Van Langenhove, Jan P. van Meerbeeck, Karim Y. Vermaelen. In vitro metabolomics of mesothelioma: Challenges and outcomes [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 204. doi:10.1158/1538-7445.AM2017-204