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PubMed2006

Volatile organic compounds released by the entomopathogenic fungus Beauveria bassiana.

The composition of volatile organic compounds (VOC) released by the entomopathogenic fungus Beauveria bassiana (Hyphomycete: Deuteromycotina) utilizing two different carbon sources was investigated. Analyses were performed by solid-phase microextraction (SPME) coupled to capillary gas chromatography (CGC) and CGC-mass spectrometry (MS). Major components in glucose-grown cultures were diisopropyl naphthalenes, ethanol, and sesquiterpenes. Alkane-grown fungal VOC switched to a fingerprint with prevalence of n-decane. This is the first report on the volatiles released by entomopathogenic fungi.

Alkanes↗
PubMed2005

Wound-induced green leaf volatiles cause the release of acetylated derivatives and a terpenoid in maize.

Green leaf volatiles (GLVs), generally occurring C6 alcohols, aldehydes and acetates from plants, play an important role in plant-plant communication. These compounds induce intact plants to produce jasmonic acid, and induce defense-related gene expression and the release of volatile compounds. Here, we address wound-induced GLVs cause the release of acetylated derivatives and a terpenoid, (E)-4,8-dimethylnona-1,3,7-triene (DMNT) in intact maize, which may be a type of plant-plant interaction mediated by airborne GLVs. Upon exposure of intact maize seedlings to wound-induced GLVs, (Z)-3-hexenyl acetate was consistently the most abundant compound released. Exogenous application of individual alcohols and aldehydes mostly resulted in the release of corresponding acetate esters. C6-alcohols with a double bond between the second and third, or the third and fourth carbon atoms, C5- or C6-aldehydes, and (Z)-3-hexenyl acetate triggered the release of DMNT. When (Z)-3-hexenyl acetate and hexyl acetate were used to treat maize seedlings, they were recovered from the plants. These data demonstrated that: (1) apart from direct adsorption and re-release of acetate esters, absorption and conversion of exogenous alcohols and aldehydes into acetate esters occurred, and (2) DMNT was induced by a range of aldehydes and unsaturated alcohols.

Acetates↗
PubMed2004

Estimating the biogenic emissions of non-methane volatile organic compounds from the North Western Mediterranean vegetation of Catalonia, Spain.

An estimation of the magnitude of non-methane volatile organic compounds (NMVOCs) emitted by vegetation in Catalonia (NE of the Iberian Peninsula, Spain), in addition to their superficial and temporal distribution, is presented for policy and scientific (photochemical modelling) purposes. It was developed for the year 2000, for different time resolutions (hourly, daily, monthly and annual) and using a high-resolution land-use map (1-km2 squared cells). Several meteorological surface stations provided air temperature and solar radiation data. An adjusted mathematical emission model taking account of Catalonia's conditions was built into a geographic information system (GIS) software. This estimation uses the latest information, mainly relating to: (1) emission factors; (2) better knowledge of the composition of Catalonia's forest cover; and (3) better knowledge of the particular emission behaviour of some Mediterranean vegetal species. Results depict an annual cycle with increasing values in the March-April period with the highest emissions in July-August, followed by a decrease in October-November. Annual biogenic NMVOCs emissions reach 46.9 kt, with monoterpenes the most abundant species (24.7 kt), followed by other biogenic volatile organic compounds (e.g. alcohols, aldehydes and acetone) (16.3 kt), and isoprene (5.9 kt). These compounds signify 52%, 35% and 13%, respectively, of total emission estimates. Peak hourly total emission for a winter day could be less than 10% of the corresponding value for a summer day.

Environmental Monitoring↗
PubMed2006

The biogenic volatile organic compounds emission inventory in France: application to plant ecosystems in the Berre-Marseilles area (France).

An inventory describing the fluxes of volatile organic compounds (VOCs), isoprene and monoterpenes, and other VOCs (OVOCs) from the biosphere to the atmosphere, has been constructed within the framework of the ESCOMPTE project (fiEld experimentS to COnstrain Models of atmospheric Pollution and Transport of Emissions). The area concerned, located around Berre-Marseilles, is a Mediterranean region frequently subject to high ozone concentrations. The inventory has been developed using a fine scale land use database for the year 1999, forest composition statistics, emission potentials from individual plant species, biomass distribution, temperature and light intensity. The seasonal variations in emission potentials and biomass were also taken into account. Hourly meteorological data for 1999 were calculated from ALADIN data and these were used to predict the hourly isoprene, monoterpene and OVOC fluxes for the area on a 1 kmx1 km spatial grid. Estimates of annual biogenic isoprene, monoterpene and OVOC fluxes for the reference year 1999 were 20.6, 38.9 and 13.3 kt, respectively, Quercus pubescens, Quercus ilex, Pinus halepensis and garrigue vegetation are the dominant emitting species of the area. VOC emissions from vegetation in this region contribute approximately 94% to the NMVOC (non-methane volatile organic compounds) of natural origin and are of the same order of magnitude as NMVOC emissions from anthropogenic sources. These results complete the global ESCOMPTE database needed to make an efficient strategy for tropospheric ozone reduction policy.

Ecosystem↗
PubMed2006

Volatiles from the venom of five species of paper wasps (Polistes dominulus, P. gallicus, P. nimphus, P. sulcifer and P. olivaceus).

The venom volatiles of five paper wasp species, four European belonging to the subgenus Polistes sensu stricto (P. dominulus, P. gallicus, P. nimphus, P. sulcifer) and one belonging to the Asian subgenus Gyrostoma (P. olivaceus), have been sampled by headspace solid phase micro-extraction and analysed by gas chromatography-mass spectrometry. The venom volatile components of Polistes wasps have never been fully investigated before, although the presence of some spiroacetals has been previously reported in literature. The composition of the venom was qualitatively and quantitatively different among the analysed species with the major substances tentatively identified, on the basis of their mass spectra, as: spiroacetals, mainly 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane, two amides, N-(3-methylbutyl)acetamide and N-(3-methylbutyl)propanamide and acetates of saturated, mono- and di-unsaturated 2-alcohols with an odd number of carbon atoms in the chain. The acetate of a di-unsaturated 2-alcohol, present in two isomeric forms, identified as (E)- and (Z)-5-tangerinol has never been reported in literature for insects. Propanoates of the same 2-alcohols were only found in the venom of P. gallicus. Both the amides and the above-mentioned spiroacetal have been already shown to be alarm pheromones in other social wasps, while the acetates and propanoates have ever been reported in this taxon.

Animals↗
PubMed2004

Multiple functions of inducible plant volatiles.

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

Atmosphere↗
PubMed2005

Repartition of PCDD and PCDF in the emissions of municipal solid waste incinerators between the particulate and volatile phases.

The present paper refers to the results of a research project on the polychlorinated dibenzyil-p-dioxin (PCDD) and polychlorinated dibenzofurans repartition in particulate and volatile phase in emissions from municipal solid waste incinerators. The distribution of such micropollutants between the different phases is analyzed in terms of absolute weights and in terms of 2, 3, 7, 8 TCDD Equivalents. This paper shows that more than half of the total content of PCDD/Fs emitted are adsorbed in the fly ash, with the remaining part in the volatile phase. Such repartition is inverted if the PCDD/Fs are expressed in terms of 2, 3, 7, 8 TCDD Equivalent.

Adsorption↗
PubMed1997

Airway symptoms among house painters in relation to exposure to volatile organic compounds (VOCS)--a longitudinal study.

The increased use of water-based paint (WBP) for indoor application during the last decade has drastically changed the exposure conditions for Swedish house painters. WBP has a lower emission of volatile organic compounds (VOCs) than solvent-based paint (SBP), but contains more reactive compounds, such as biocides, glycol ethers, and other high molecular solvents. The aim of this study was to compare the incidence of airway symptoms and self-reported asthma in house painters with a different degree of use of WBP and SBP. The incidence of seven general airway symptoms, and three work-related symptoms, was analysed by means of a self-administered questionnaire, in a cohort of 207 house painters followed from 1989 to 1992. Different airway symptoms were compared with clinical information obtained by a methacholine challenge test and dynamic spirometry in a selected subgroup of 44 painters. Information on the degree of use of SBP and WBP was used to estimate the total exposure to volatile organic compounds (TVOC) for each individual. In total, 175 men in the cohort worked as painters during the study period. No increase of asthma or respiratory symptoms was observed among those 50 painters with a pure exposure to WBP (estimated TVOC 1-3 mg m-3). Most painters (N = 125) had a mixed exposure to SBP and WBP, the main source of the TVOC being the limited use of SBP. WBP was perceived as less irritative than SBP, but complaints on airway irritation from WBP increased during the study period. The most pronounced increase of airway irritation in relation to both SBP and WBP, was observed among those 35 painters with the highest solvent exposure (estimated TVOC 100-380 mg m-3). An increase of respiratory symptom index and shortness of breath, in relation to estimated TVOC exposure was also observed. Selection effects were detected. Painters leaving their job during the study period had more non-specific hyper-reactivity symptoms, and more airway irritation from WBP, as compared to painters remaining at their occupation. Our study indicates that VOC emissions from SBPs may contribute to the development of respiratory symptoms and airway irritation. We found no increase of respiratory symptoms among painters exposed only to WBPs. There were, however, indications that VOC exposure from WBPs may cause airway irritation in some subjects. Because of selection effects, cross-sectional studies on respiratory symptoms in relation to occupational exposure to paint emissions may be inconclusive.

Adult↗
PubMed2000

Evidence for selectivity of absorption of volatile organic compounds by a polydimethylsiloxane solid-phase microextraction fibre.

Solid-phase microextraction using a 30 microns polydimethylsiloxane fibre has been used to sample the volatile organic compounds from standard mixtures and from mixtures produced by the decomposition of organic compounds. This method of sampling has been compared with the direct injection of an aliquot of headspace gas and shows an enrichment factor of approximately 100 over a 1 ml gas injection for organosulphur gases such as dimethyldisulphide. The performance of the fibre has been evaluated with respect to accuracy and precision at several concentrations in representing the composition of multicomponent mixtures. It was found that the presence of a second component in a gas sample reduced the capacity of the fibre to absorb the primary component. The selectivity of the fibre for various volatile compounds with differing functionality was also studied. It was found that the non-polar polydimethylsiloxane fibre preferentially absorbed the non-polar components of a mixture, e.g. nonane and, correspondingly, under reported the more polar components, e.g. ethanol. Hence, the fibre discriminates in favour of non-polar and against polar components in a mixture in comparison with direct analysis of a headspace sample. Thus, quantitation of a component in a multi-component mixture is liable to error from competitive interference from other components. A major advantage of the technique, however, is that it does not absorb, and therefore introduce, water into the analytical system.

Absorption↗
PubMed2000

Cryogen free automated gas chromatography for the measurement of ambient volatile organic compounds.

An automated gas chromatographic system was constructed for measuring ambient volatile organic compounds (VOCs). Preconcentration of the VOCs was performed by using two separated sorbent traps of different combinations with each designated for either low or high boiling VOCs. Both traps and their associated valve systems were integrated as a complete system sharing a common sample inlet. Precise temperature controls for desorption relied on the use of a process controller with proportional-integral-derivative algorithm to throttle the current supply. No additional cryo-focusing stage prior to the column was needed owing to the flash heating capability for desorption. Other than the cryogen free preconcentration and focusing, the separation of VOCs of large volatility difference was also performed without cryogen. The system employed an Al2O3/KCl porous-layer open tubular column for separating C3-C7 compounds; and a DB-1 column for C6-C12. This automated GC system has been deployed in a Taiwan Environmental Protection Agency urban air quality monitoring station of Taiwan for continuous measuring C3-C7 ozone precursors. Excellent correlation between the car exhaust type of compounds measured by our GC system and carbon monoxide measured by a non-dispersive infrared spectrometer was observed, suggesting the automated GC system was robust and reliable.

Automation↗
PubMed2000

Retention index database for identification of general green leaf volatiles in plants by coupled capillary gas chromatography-mass spectrometry.

A series of ubiquitously occurring saturated and monounsaturated six-carbon aldehydes, alcohols and esters thereof is summarised as 'green leaf volatiles' (GLVs). The present study gives a comprehensive data collection of retention indices of 35 GLVs on commonly used non-polar DB-5, mid-polar DB-1701, and polar DB-Wax stationary phases. Seventeen commercially not available compounds were synthesised. Thus, the present study allows reliable identification of most known GLV in natural plant volatile samples. Applications revealed the presence of several seldom reported GLVs in headspace samples of mechanically damaged plant leaves of Carpinus betulus and Fagus sylvatica.

Database Management Systems↗
PubMed2000

Microwave-assisted derivatization of volatile carbonyl compounds with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine.

A method for the determination of carbonyl compounds, either directly from gaseous phase or following a volatilization from liquid or solid samples after trapping on Tenax TA is presented. Following solvent desorption, the carbonyls are derivatized using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine. The reaction is accomplished in a microwave oven using closed vessels to minimize reaction time compared to conventional methodology. The solvent for the chemical reaction was selected according to the requirements of microwave energy interaction and solubility. After gas chromatographic separation of the corresponding oximes, they are detected using electron impact mass spectrometry in single ion monitoring mode. Quantification is carried out using internal standardization with 3-fluorobenzaldehyde, resulting in limits of detection in the ppm range following the calibration graph method. The optimized conditions provide for good recoveries and fast reaction rates for the volatile carbonyls studied so far.

Calibration↗
PubMed1978

Headspace volatiles of marihuana and hashish: gas chromatographic analysis of samples of different geographic origin.

The sweet odor of marihuana is of interest for instrumental monitoring of illicit drug traffic and for applications in forensic work. Headspace volatiles of marihuana and hashish of different origin are examined by gas chromatography, and relative compositions of 24 samples are compared. No correlation between volatile make up and geography was found, but the profiling procedures are shown to be of use in the forensic problem of relating samples to a common source.

Cannabis↗
PubMed2001

Evaluation of tetraglyme for the enrichment and analysis of volatile organic compounds in air.

A recently developed method for the sampling and analysis of volatile organic compounds in air has been evaluated. The system is based on the enrichment of analytes in tetraethylene glycol dimethyl ether or tetraglyme, a water-soluble organic liquid. The subsequent analysis consists of dispersion of a sample aliquot in water followed by purge-and-trap and gas chromatographic separation. Physico-chemical data were investigated for 10 volatile organic compounds, providing information on the possibilities and limitations of the tetraglyme method. The target analytes included chlorinated alkanes and alkenes, and monocyclic aromatic hydrocarbons. Air/tetraglyme partition coefficients Kat were determined over an environmental relevant temperature range of 2-25 degrees C to evaluate sorption efficiencies and estimate breakthrough volumes at the sampling stage. At 2 degrees C breakthrough volumes (allowing 5% of breakthrough) ranged from 5.8 (1,1-dichloroethane) to 312 l (1,1,2-trichloroethane) for 20 ml of tetraglyme. With regard to the desorption stage, the effect of tetraglyme on the air/water partition of organic compounds was investigated through the measurement of air/tetraglyme-water partition coefficients Kat-w for 2-31% (v/v) tetraglyme in water. Finally a clean-up procedure for tetraglyme was evaluated. Analysis of a blank tetraglyme-water (17:83, v:v) mixture by gas chromatography-flame ionization detection/mass spectrometry showed minor background signals. None of the target compounds were detected.

Air↗
PubMed2001

Comparison of simultaneous distillation extraction and solid-phase microextraction for the determination of volatile flavor components.

Traditional simultaneous distillation extraction (SDE) and solid-phase microextraction (SPME) techniques were compared for their effectiveness in the extraction of volatile flavor compounds from various mustard paste samples. Each method was used to evaluate the responses of some analytes from real samples and calibration standards in order to provide sensitivity comparisons between the two techniques. Experimental results showed traditional SDE lacked the sensitivity needed to evaluate certain flavor volatiles, such as 1,2-propanediol. Dramatic improvements in the extraction ability of the SPME fibers over the traditional SDE method were noted. Different SPME fibers were investigated to determine the selectivity of the various fibers to the different flavor compounds present in the mustard paste samples. Parameters that might affect the SPME, such as the duration of absorption and desorption, temperature of extraction, and the polarity and structure of the fiber were investigated. Of the various fibers investigated, the PDMS-DVB fiber proved to be the most desirable for these analytes.

Chromatography, Liquid↗
PubMed2001

Chemical characterisation of the different types of volatile oil constituents by various solute retention ratios with the use of conventional and novel commercial gas chromatographic stationary phases.

Retention ratios of an unknown solute peak from a volatile oil can help to identify its chemical type. Relative retentions on conventional stationary phases can be used to calculate a polar/non-polar ratio which may suggest it is an aromatic solute or a sesquiterpene hydrocarbon. With dipentyl (DA) cyclodextrin phases, gamma-DA/alpha-DA ratios can indicate a bicyclic or monocyclic monoterpenoid. Temperature change on alpha-DA can pick out a non-alcoholic saturated cyclic monoterpenoid, using 150/125 degrees C. Twenty retention ratios are reviewed involving various phases, including other modified cyclodextrins, liquid crystals, "Chirasil-Val" and crown ethers. Applications to six volatile oils are made using a variety of phases.

Chromatography, Gas↗
PubMed2002

Optimization of headspace sampling using solid-phase microextraction for volatile components in tobacco.

Solid-phase microextraction (SPME) was evaluated as a tool for headspace sampling of tobacco samples. Several experimental parameters (e.g. sampling temperature, pH, moisture, and the type of SPME fibers) were optimized to improve sampling efficiency in two aspects; maximum adsorption and selective adsorption of volatile components onto SPME fibers. The effect of these parameters was often dominated by the physical and chemical nature (e.g. volatility, polarity) of target compounds, thus, SPME sampling conditions can be adjusted to favor a selected group of compounds, such as organic acids in tobacco.

Gas Chromatography-Mass Spectrometry↗
PubMed2002

Rapid determination of volatile constituents of Michelia alba flowers by gas chromatography-mass spectrometry with solid-phase microextraction.

The volatile constituents of Michelia alba flowers, including fresh flowers, frozen flowers and withered flowers, were investigated by GC-MS. The volatiles in a simulated natural environment were sampled by solid-phase microextraction (SPME), with a 100 microm polydimethylsiloxane fiber at 25+/-5 degrees C for 4 h. The fibers were desorbed in a GC injection liner at 250 degrees C for 3 min. With headspace SPME-GC-MS analysis, 61 peaks were separated. The main compounds in headspace of fresh Michelia alba flowers included alpha-myrcene, (S)-limonene, (R)-fenchone, linalool, camphor, caryophyllene, germacrene D, etc., a greater number of compounds than for frozen flowers and withered flowers. At the same time, the biomarkers of fresh flowers were compared with the frozen flowers and withered flowers. In this study, headspace SPME-GC-MS afforded a simple and more sensitive sampling method for fresh Michelia alba flowers and other fresh flowers.

Gas Chromatography-Mass Spectrometry↗