Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Volatilization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56Linked to original sources
PubMed2002

Volatile organic pollutants in new and established buildings in Melbourne, Australia.

Volatile organic compounds (VOCs) within new and established buildings have been determined and factors significant to their presence have been identified. In established dwellings, total volatile organic compound (TVOC) concentrations were low, but were approximately four times higher than in outdoor air, showing a dominant effect of indoor sources. The presence of attached garages, site contamination and 'faulty' wool carpet were associated with higher indoor pollution. In three dwellings, unidentified sources of benzene were indicated. Much higher VOC concentrations were observed in new or renovated buildings, persisting above "baseline" levels for several weeks, concentration decay rate correlating with VOC molecular volume, indicating emissions were limited by material diffusion processes. VOC and formaldehyde emission decays in a new dwelling occurred by a double-exponential source model. This shows that persistent low levels of volatile organic pollutants in established dwellings can occur due to long-term emissions from building materials.

Air Pollution, Indoor↗
PubMed2003

A screening assessment of emissions of volatile organic compounds and particles from heated indoor dust samples.

This paper characterizes and compares emissions during heating of different dust samples relevant to the indoor environment. Characterization includes emission of volatile organic compounds when dust samples were heated to 150 and 250 degrees C (gas chromatograph-mass spectrometer), weight loss during heating to 450 degrees C (thermogravimetric analysis), and the number of particles emitted during heating towards 200 degrees C (condensation nucleus counting). Element analyses were performed for non-heated dust (inductively coupled plasma discharge instrument). Emissions of volatile organic compounds from heated dust from different sources were surprisingly similar. However, the temperature at which the emission of volatiles started varied with the dust source. For most of the samples studied, the emissions were considerable already at 150 degrees C, and increased in number of peaks and peak area at 250 degrees C. Particle emissions started around 70 degrees C regardless of the dust source. Particle emissions seemed to be affected by the content of organic material.

Air Pollutants↗
PubMed2004

Engineered endophytic bacteria improve phytoremediation of water-soluble, volatile, organic pollutants.

Phytoremediation of highly water soluble and volatile organic xenobiotics is often inefficient because plants do not completely degrade these compounds through their rhizospheres. This results in phytotoxicity and/or volatilization of chemicals through the leaves, which can cause additional environmental problems. We demonstrate that endophytic bacteria equipped with the appropriate degradation pathway improve the in planta degradation of toluene. We introduced the pTOM toluene-degradation plasmid of Burkholderia cepacia G4 into B. cepacia L.S.2.4, a natural endophyte of yellow lupine. After surface-sterilized lupine seeds were successfully inoculated with the recombinant strain, the engineered endophytic bacteria strongly degraded toluene, resulting in a marked decrease in its phytotoxicity, and a 50-70% reduction of its evapotranspiration through the leaves. This strategy promises to improve the efficiency of phytoremediating volatile organic contaminants.

Biodegradation, Environmental↗
PubMed2001

Volatile hydrocarbon biodegradation by a mixed-bacterial culture during growth on crude oil.

Volatile hydrocarbon biodegradation by a mixed-bacterial culture during growth on Bow River crude oil was investigated using solid phase microextraction (SPME). Inoculum treatments were examined in relation to C(5)-C(11) hydrocarbon degradation. Up to 1600 mg/l biomass (dry weight) was tested without achieving significant volatile hydrocarbon partitioning and affecting analysis. Inoculum age rather than concentration had the most profound impact on biodegradation. When late log phase crude oil-grown inocula were used, C(5)-C(11) biodegradation reached 55-60%; methylcyclohexane and other branched compounds eluting before n-C(8) were recalcitrant. Increasing the late log inoculum concentration from 0.63 to 63 mg/l resulted in a twofold increase in degradation rate without improving the substrate range. Methylcyclohexane recalcitrance was correlated with reduced levels of hydrocarbon-degrading bacteria and volatile hydrocarbon evaporation from the inoculum flasks. A decreased lag phase prior to degradation was observed when using early stationary phase cultures as inocula and most compounds up to C(11), including methylcyclohexane, were biodegraded.

Bacteria↗
PubMed2002

Patterns and levels of halogenated volatile compounds in Portuguese surface waters.

The present study focused on monitoring the concentration of 14 halogenated volatile organic compounds in surface waters, including sea, estuarine, river water and industrial effluents in order to determine the most ubiquitous compounds and their concentration levels, which were used to establish their geographical and temporal distribution. EPA Method 502, based on purge and trap techniques, was used. In this method volatile organic pollutants are extracted (purged) from the water sample by bubbling inert gas through the aqueous sample. Purged sample components are trapped in a cartridge containing the polymeric sorbent Tenax and, thereafter, the cartridge is heated and backflushed with helium to desorb the trapped sample components directly into a gas chromatograph with electron capture detector (GC-ECD). The linearity range of the method varied from 0.1 to 4 microg L(-1) with a limit of detection at the low microg L(-1) level. The present study consisted of a monthly monitoring of 46 points throughout Portugal, during 14 months. Chloroform was found in 50% of the samples analyzed, its presence being correlated to both agricultural and industrial activities. Other compounds detected were tetrachloroethylene, trichloroethylene, carbon tetrachloride and 1,2,4 trichlorobenzene, which were present in 10-20% of the samples at concentrations up to 18 microg L(-1). 1,1,2,2-Tetrachloroethane and its degradation product 1,1,2-trichloroethane were found in 5% of the samples, the levels of the latter being higher than those of the parent compound in most samples. Sporadic high concentrations of some volatile halogenated organic compounds were attributed to local uses as solvents.

Agriculture↗
PubMed2002

Volatile metabolites from microorganisms grown on humid building materials and synthetic media.

Growth of different microorganisms is often related to dampness in buildings. Both fungi and bacteria produce complicated mixtures of volatile organic compounds that include hydrocarbons, alcohols, ketones, sulfur- and nitrogen-containing compounds etc. Microbially produced substances are one possible explanation of odour problems and negative health effects in buildings affected by microbial growth. A mixture of five fungi, Aspergillus versicolor, Fusarium culmorum, Penicillium chrysogenum, Ulocladium botrytis and Wallemia sebi were grown on three different humid building materials (pinewood, particle board and gypsum board) and on one synthetic medium. Six different sampling methods were used, to be able to collect both non-reactive volatile organic compounds and reactive compounds such as volatile amines, aldehydes and carboxylic acids. Analysis was performed using gas chromatography, high-performance liquid chromatography and ion chromatography, mass spectrometry was used for identification of compounds. The main microbially produced metabolites found on pinewood were ketones (e.g. 2-heptanone) and alcohols (e.g. 2-methyl-1-propanol). Some of these compounds were also found on particle board, gypsum board and the synthetic medium, but there were more differences than similarities between the materials. For example, dimethoxymethane and 1,3,5-trioxepane and some nitrogen containing compounds were found only on particle board. The metabolite production on gypsum board was very low, although some terpenes (e.g. 3-carene) could be identified as fungal metabolites. On all materials, except gypsum board, the emission of aldehydes decreased during microbial growth. No low molecular weight carboxylic acids were identified.

Air Pollution, Indoor↗
PubMed2002

Headspace solid-phase microextraction--comprehensive two-dimensional gas chromatography of wound induced plant volatile organic compound emissions.

Plant emissions of volatile organic compounds from mechanically wounded Agrostis stolonifera, Pennisetum clandestinum, Eucalyptus leucoxylon and Trifolium repens have been sampled by headspace-solid phase microextraction (HS-SPME) and analysed by using comprehensive two-dimensional gas chromatography (GCxGC) for measurement of the plant emissions. GCxGC produces a fingerprint of the volatile organic compounds in a 2D separation space that may be approximately interpreted as a boiling point-polarity space, and may then be presented as a two-dimensional contour plot. This allows identification of sample-dependent variations in component distributions in the 2D plot, which will contain information about plant differences and should therefore facilitate recognition of different plant materials and displays the gross differences in volatiles between each plant species.

Agrostis↗
PubMed2004

Background concentrations of individual and total volatile organic compounds in residential indoor air of Schleswig-Holstein, Germany.

During a monitoring campaign concentrations of volatile organic compounds (VOCs) were measured in indoor air of 79 dwellings where occupants had not complained about health problems or unpleasant odour. Parameters monitored were the individual concentration of 68 VOCs and the total concentration of all VOCs inside the room. VOCs adsorbed by Tenax TA were then analysed by means of thermal desorption, gas chromatography and mass spectrometry. The analytical procedure and quantification was done according to the recommendation of the ECA-IAQ Working Group 13 which gave a definition of the total volatile organic compound (TVOC) concentration. Using this recommendation TVOC-concentrations ranged between 33 and 1600 microg m(-3) with a median of 289 microg m(-3). Compounds found in every sample and with the highest concentrations were 2-propanol, alpha-pinene and toluene. Save for a few samples, all concentrations measured have been a factor 2 to 10 lower, compared to data from similar studies. Only a few terpenes and aldehydes were found exceeding published reference data or odour threshold concentrations. However, it has been found that sampling and analysing methods do have a considerable impact on the results, making direct comparisons of studies somewhat questionable. 47% of all samples revealed concentrations exceeding the threshold value of 300 microg TVOC m(-3) set by the German Federal Environmental Agency as a target for indoor air quality. Using the TVOC concentration as defined in the ECA-IAQ methodology is instrumental in assessing exposure to VOCs and identifying sources of VOCs. The background concentrations determined in this study can be used to discuss and interpret target values for individual and total volatile organic compounds in indoor air.

Air Pollution, Indoor↗
PubMed2005

Membrane-introduced infrared spectroscopic chemical sensing method for the detection of volatile organic compounds in aqueous solutions.

A novel membrane-introduced infrared (IR) chemical sensing method has been developed for the detection of volatile organic compounds (VOCs) in aqueous solutions. In this method, a porous Teflon membrane was used to eliminate the problems associated with conventional IR spectroscopic sensing methods. The porous Teflon membrane was sealed below an IR spectroscopic sensing element pre-coated with a hydrophobic film and a two-channel flow cell configuration was established. In this configuration, the aqueous sample was allowed to pass through the lower channel and the VOCs that penetrated through the membrane to the upper channel were detected by the IR sensor. In this manner, the performance of the sampling at the headspace was improved while the problems caused by the presence of water were eliminated. Meanwhile, using a purging channel allowed the sensing element to be regenerated rapidly and enabled automation of the detection process. The parameters that influenced the analytical signals were studied, such as the sampling flow rate, the pH and ionic strength of the sample solutions, the effect of the volatilities of the VOCs, and the regeneration efficiency of the sensing element. The results indicated that the analytical signals were insensitive to the sampling flow rate and to the pH and ionic strength of the sample solutions. The results obtained from the detection of seven different volatile compounds indicated that this method is highly suitable for the detection of organic compounds that have vapor pressures >1 Torr and that it is potentially usable for organic compounds that have vapor pressures between 20 mTorr and 1 Torr. The regression analysis of the standard curves indicated that a regression coefficient (R(2)) > 0.99 was obtainable in the concentration range from 1 to 100 microg mL(-1). The detection limits for the tested compounds were around a few hundred ng mL(-1).

Hydrogen-Ion Concentration↗
PubMed2005

A short-term test adapted to detect the genotoxic effects of environmental volatile pollutants (benzene fumes) using the filamentous fungus Aspergillus nidulans.

With the recent focus on environmental problems, increasing awareness of the harmful effects of industrial and agricultural pollution has created a demand for progressively more sophisticated pollutant and toxicity detection methods. Using Aspergillus nidulans strains this work presents a new short term-test that, most importantly, enables the rapid and inexpensive detection of volatile pollutants that induce genotoxic/carcinogenic effects in animals. The main aim is to contribute to environmental health protection, and special attention is directed to monitoring the hazard posed by benzene (as a carcinogenic agent model) mainly because its ubiquitous presence often leads to severe noxious effects in humans among whom increased rates of human leukemia have been reported. To evaluate even the submutagenic effects of benzene fumes, two Aspergillus nidulans diploid strains, heterozygous for several auxotrophic mutations, were used. The DNA lesions produced stimulate mitotic recombination and homozygotization of auxotrophic recessive mutations. Conidial exposure to a saturated atmosphere of benzene fumes for 20 s was enough to increase the mitotic recombination frequencies significantly. Genetic analyses of treated diploids evidenced alterations related to mitotic recombination frequencies, gene expression, and allelic segregation rates. Altogether they reflect the potential of benzene to induce alterations in the fungal DNA, and albeit indirectly, they also respond for the genotoxic/carcinogenic harmful side effects widely connected to benzene. This is the first description of a sensitive, rapid and inexpensive test able to detect the submutagenic dose effects of volatile environmental compounds. In addition, despite concentrating on benzene the same test can be applied to many other pollutants, volatile or not. Additionally, the test can also be used to detect the antigenotoxic properties of foods and drugs.

Air Pollutants↗
PubMed2001

Characterization of lactic acid bacteria strains on the basis of neutral volatile compounds produced in whey.

AIMS: Seventy-eight strains of lactic acid bacteria belonging to five genera and showing six different phenotype combinations of Lac (lactose fermentation), Prt (proteolytic activity) and Cit (citrate degradation) characters were investigated for their main flavouring properties with the aim to detect variability among and within the groups. METHODS AND RESULTS: High resolution gas chromatography-mass spectrometry analysis of neutral volatile compounds produced in whey showed that, considering both neo-formation compounds and substances quantified in the whey cultures at different concentrations in comparison to the extract from sterile whey, the groups of lactococci, enterococci, thermophilic streptococci and mesophilic lactobacilli produced a higher number of volatiles than thermophilic lactobacilli and leuconostocs. Applying principal component analysis (PCA) to the results, enterococci, mesophilic lactobacilli and thermophilic streptococci showed a broad diversity, while lactococci included rather similar strains as well as strains with special flavouring properties. Applying PCA to thermophilic streptococci and enterococci, to lactococci and enterococci, to lactococci and thermophilic streptococci, or to mesophilic and thermophilic lactobacilli, the strains gathered consistently with their systematic position. CONCLUSION: The study evidenced strains producing some volatile compounds responsible for food flavouring. Flavouring properties were variable among the systematic groups and in some cases different within the same bacterial group. SIGNIFICANCE AND IMPACT OF THE STUDY: The potential of the findings is discussed with reference to the development of flavouring adjuncts for the dairy industry.

Cluster Analysis↗
PubMed2000

Microbial populations and volatile compounds in the 'bone taint' spoilage of dry cured ham.

'Bone taint' is one of the most important causes of spoilage of dry cured ham. This alteration is characterized by a foul-smelling odour. The microbial population and volatile compounds associated with incipient 'bone taint' were evaluated. Enterobacteriaceae species were found at levels of 7.94 x 10(5) cfu g(-1) in spoiled hams and were not detected in unspoiled hams. Serratia sp. and Proteus sp. are the main organisms characterized. The volatile compounds from the spoiled hams give rise to higher levels of ketones, alcohols and esters than unspoiled hams, that could be originated by microbial metabolism of the above bacteria. Thus, volatile and Enterobacteriaceae analyses should be used to determine this incipient spoilage in the meat industry.

Alcohols↗
PubMedDate not supplied

Effect of adding sugar beet fibre and wheat bran to a starch diet on the absorption kinetics of glucose, amino-nitrogen and volatile fatty acids in the pig.

The purpose of this study with the pig was to analyse the influence of the type of dietary fibre on quantitative kinetics of the absorption of nutrients deriving from enzymatic digestion in the small intestine and that of volatile fatty acids (VFA) deriving from microbial digestion in the hindgut influenced by the length of adaptation to the diet. Two groups of four pigs were fitted with a device for measuring absorption by simultaneous analysis of the differences in the porto-arterial concentrations of nutrients and metabolites and of the portal blood flow rate. They received successively two diets containing fish- and heat-treated potato flour, balanced in vitamins and minerals, and only differing in the type of fibre added at the inclusion level of 10%: wheat bran (S) or sugar beet fibre (P). Following an adaptation period of 30 d (C) or 5 d (A) to each of these diets, and after the last experimental meal of 800 g, the animals were subjected for 12 h to blood samplings every 30-60 min for the analysis of glucose, amino-nitrogen and volatile fatty acids (VFA) with a simultaneous recording of the portal blood flow-rate. The type of dietary fibre did not modify nutrient absorption (glucose and amino-nitrogen) but affected the amounts of VFA appearing in the portal blood. These amounts were higher (P < 0.001) after ingestion of the sugar beet fibre-rich diet (group PC + PA: 766 mmol/12 h) than after that of the wheat bran-rich diet (group SC + SA: 477 mmol/12 h). The proportion of acetic acid in the absorbed mixture rose (PC + PA 63.6% versus SC + SA 58.5%, P < 0.01) at the expense of propionic acid (PC + PA 27.4% versus SC + SA 31.0%, P < 0.01). Prolongation of the adaptation period from 5 to 30 d led to a decrease in the absorption of nutrients deriving from enzymatic digestion in the small intestine (glucose g/12 h: SA + PA 341.8 versus SC + PC 244.5, P < 0.01; amino-nitrogen g/12 h: SA + PA 29.4 versus SC + PC 21.0, P < 0.001) without any subsequent change in the absorption of the volatile fatty acids.

Absorption↗
PubMedDate not supplied

Effects of level and type of energy source (volatile fatty acids or glucose) on milk yield, composition and coagulating properties in dairy cows.

Four fistulated Holstein cows were arranged in a 4 x 4 Latin square design to study the effects of level and type of energy source on milk yield and composition. Treatments consisted of a basal diet fed alone (low energy treatment) or with 3.3 Mcal of net energy for lactation from extra nutrients perfused either into the rumen (either propionic acid or a mixture of volatile fatty acids) or into the duodenum (glucose). Increasing the energy input without changing the volatile fatty acid profile improved milk yield and slightly increased milk protein and fat yields. Compared with the isoenergetic mixture of volatile fatty acids, both propionic acid and glucose infusions significantly decreased fat content (-4.5 g/kg) and yields (respectively, -111 and -160 g/d), but affected fatty acid proportion and yield differently (more elongation process and less C18 with glucose infusion). Protein yield was slightly increased by propionic acid infusion but not by glucose because of the counterbalanced effects on milk yield (-1.3 kg/d) and protein content (1.5 g/kg). The coagulating properties of milk were directly linked to variations in protein, casein and mineral contents. In conclusion, propionic acid or glucose scarcely affected milk protein content, but induced a similar decrease in milk fat content probably through different metabolic pathways.

3-Hydroxybutyric Acid↗
PubMed2005

A simple field method to determine mercury volatilization from soils.

BACKGROUND: Estimations of gaseous mercury volatilization from soils are often complex, stationary and expensive. Our objective was to develop a mobile and more simple, easy to handle and more cost-effective field method allowing rapid estimates of potential Hg emissions from soils. METHODS: The study site is located in Germany, about 100 kilometers south-westerly of Berlin and influenced by the river Elbe and its tributary Saale river. The site is representative for a lot of other floodplain locations at the river Elbe and highly polluted with Hg and other heavy metals. For our study we developed a system consisting of a glass chamber gas, two gold traps, a battery operated pump and a gas meter. Adsorbed total gaseous mercury (TGM) in the gold traps was determined by use of atomic absorption spectrometry (AAS). RESULTS AND DISCUSSION: In contrast to the common used flux chambers we designed a chamber without inlet and named it gas suck up chamber (GSC). TGM fluxes determined with the GSC showed a very close linear correlation (r = 0.993) between the TGM content in the gold traps and the corresponding pumped gas volume. The TGM adsorbed, increased proportional with increasing gas volume indicating homogenous concentrations of gaseous mercury in the soil air sucked. In contrast to the commonly used dynamic flux chamber with the aim of precisely measuring actual fluxes of Hg from a defined soil area, we focused on developing of a measurement system which will allow rapid estimates of potential Hg emissions of a site. Earlier research at the study site indicated a high potential for releasing volatile Hg from the soil to the atmosphere. Indeed, due to the high Hg content of the soil significant amounts of TGM could be detected and no shortage was reached. CONCLUSION: Our initial measurements are still too few in number neither to generalize the achieved results nor discuss controlling factors and processes. However, we are pleased to communicate that the developed GSC is well suited to become an effective sampling set up to rapidly estimate the magnitude of Hg volatilization from soils. OUTLOOK: Further measurements at other polluted locations are necessary to verify the GSC method. In addition the use of a mercury analyzer instead of gold traps is planned for faster risk assessments.

Environmental Monitoring↗
PubMed2001

Detection of microbial volatile organic compounds (MVOCs) produced by moulds on various materials.

Twelve fungal species were screened for microbial volatile organic compounds (MVOCs): Aspergillus fumigatus, A. versicolor, A. niger, A. ochraceus, Trichoderma harzianum, T. pseudokoningii, Penicillium brevicompactum, P. chrysogenum, P. claviforme, P. expansum, Fusarium solani and Mucor sp. More than 150 volatile substances derived from fungal cultures have been analysed by head-space solid-phase microextraction (HS-SPME). Each species had a defined MVOC profile which may be subjected to considerable modification in response to external factors such as cultivation on different substrata. The cultivation on different substrata changes the number and concentration of MVOCs. Species-specific volatiles may serve as marker compounds for the selective detection of fungal species in indoor environments. Examination of MVOCs from indoor air samples may become an important method in indoor air hygiene for the detection of type and intensity of masked contamination by moulds.

Air Pollution, Indoor↗
PubMedDate not supplied

Effects of packaging and storage conditions on volatile compounds in gas-packed poultry meat.

Volatile compounds released by raw chicken legs packed in modified atmosphere packages were determined in order to develop a spoilage indicator for monitoring the shelf-life of raw chicken. Internal spoilage indicators would react with compounds released during chemical, enzymatic and/or microbial spoilage reactions. The effects of four packaging factors (headspace volume, oxygen transmission rate of the package, residual oxygen and carbon dioxide concentration) and three storage factors (temperature, illumination and storage time) on the amounts of volatile compounds in the headspace of gas packages containing two chicken legs were studied. Statistical experimental design was applied and a linear screening design comprising 18 experiments (fractional factorial) was utilized. Volatile compounds in package headspace were determined by gas chromatography--mass spectrometry using the dynamic headspace technique. The results were compared with the results of sensory evaluation and microbial determinations. The head-space of stored packages was dominated by the following compounds: butene, ethanol, acetone, pentane, dimethylsulphide, carbon disulphide and dimethyl disulphide. In modelling, some interaction terms and squared terms were needed in addition to linear terms. The main factors affecting the amounts of ethanol, dimethyl sulphide, carbon disulphide and dimethyl disulphide were storage time and temperature. Other factors had only minor importance, carbon dioxide concentration and headspace volume being the most significant package parameters. The same four factors also had the greatest effects on the odour of chicken legs.

Acetone↗
PubMed1996

Volatilization of chemicals from drinking water to indoor air: role of the kitchen sink.

Contaminated tap water is one source of potentially hazardous air pollutants in residential indoor air. Contaminants have been observed to volatilize from household tap water sources, including showers, wash basins, bath-tubs, washing machines, dishwashers, and toilets. A background search of these sources led to the conclusion that more attention should be given to wash basins and tubs, the numerous operating conditions of which yield a significant range of chemical stripping efficiencies. In response, nine laboratory experiments were completed to determine chemical stripping efficiencies and mass transfer coefficients for a kitchen wash basin. Chemical stripping efficiencies ranged from 1.1% to 4.9% for acetone, 13% to 26% for toluene, and 18% to 48% for cyclohexane. The product of overall mass transfer coefficient and interfacial area (KLA) ranged from 0.06 L/min to 0.24 L/min for acetone, 0.7 L/min to 1.9 L/min for toluene, and 0.9 L/min to 3.5 L/min for cyclohexane. Results clearly indicate that chemical properties (e.g., Henry's law coefficient) and system operating conditions (e.g., liquid flow rate and nozzle type) have a significant effect on contaminant stripping efficiency. Furthermore, significant gasphase resistance can occur, even for relatively volatile contaminants, during some operating conditions. The latter observation has important implications with respect to conventional protocols used to extrapolate radon data to other volatile contaminants in drinking water.

Air Pollution, Indoor↗