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PubMed2003

Monitoring and fast detection of mycotoxin-producing fungi based on headspace solid-phase microextraction and headspace sorptive extraction of the volatile metabolites.

Solid phase microextraction in combination with capillary GC-MS was used as monitoring technique for the collection and detection of the fungal volatile metabolite (+)-aristolochene by sporulated surface cultures of Penicillium roqueforti. A comparison was made between different toxigenic and nontoxigenic strains of P. roqueforti. Different growth conditions and media, such as malt extract agar, potato dextrose agar and sabouraud dextrose agar were compared. Whereas toxigenic strains produced large amounts of (+)-aristolochene, beta-elemene, valencene and germacrene A, nontoxigenic P. roqueforti strains showed a remarkably different headspace profile, in which ethyl-2-hexenoate, E-beta-caryophyllene, aromadendrene and beta-patchoulene were the predominant volatiles, apart from other sesquiterpene hydrocarbons present at lower concentrations. Stir bar sorptive extraction, was also applied in the headspace sampling mode, i.e. headspace sorptive extraction (HSSE) for the enrichment of fungal volatiles from sporulated surface cultures to differentiate between toxigenic and nontoxigenic fungi. Hence, it can be concluded that headspace analysis of volatile fungal metabolites by SPME and HSSE in combination with capillary GC-MS is a suitable monitoring technique for the fast detection of mycotoxin producing fungi.

Gas Chromatography-Mass Spectrometry↗
PubMed2003

Comparison of methods used for pre-concentrating small volumes of organic volatile solutions.

Eight pre-concentration techniques were compared for their capacity to retain volatile and semi-volatile solutes during evaporation of solvent (dichloromethane). The 2-ml test-samples containing 0.2 ppm or 2 ppm (v/v) of volatile and semi-volatile solutes were concentrated to a final volume of 1 ml, 200 microl and 50 microl, respectively. When pre-concentrating to 50 microl, the highest recoveries for both the diluted (0.2 ppm) and concentrated (2 ppm) solutions were found by passive evaporation in a test tube at 22 degrees C. The pre-concentration time from 2 ml to 50 microl by this method was 19-20 h. Heating the test tube to 47 degrees C yielded lower recoveries in dilute samples, but the recoveries of concentrated samples were only slightly lower than the recoveries obtained by passive evaporation. The evaporation time was decreased to 1-2 h. The recoveries and the reproducibility of these methods were superior to the other pre-concentration methods tested. Loss of solute was apparently mainly caused by the fast vapour streams created when speeding up the process of evaporation by heating or by introducing a gas stream into the tube. This increased co-evaporation and thereby solute loss. The capacity of the methods to trap the escaping vapours and create a reflux determined the capacity of the methods to recover the solutes. The experiments demonstrated that more solute is lost during the pre-concentration of dilute samples compared to more concentrated solutions.

Chemical Phenomena↗
PubMed2003

Solid-phase microextraction of volatile compounds in "Terrincho" ewe cheese. Comparison of different fibers.

Solid-phase microextraction coupled to gas chromatography-mass spectrometry (GC-MS) was applied to study the volatile compounds in "Terrincho" ewe cheese. Six types of fibers were tested and the main extraction parameters were studied. Carboxen-polydimethylsiloxane fiber 75 microm (CAR-PDMS) achieved the most complete profile of ewe cheese volatile compounds. The optimised conditions used for characterization of "Terrincho" ewe cheese were: sample vial equilibration at 20 degrees C for 20 min, followed by CAR-PDMS fiber exposure to the headspace above the sample for 30 min and finally thermal desorption of the adsorbed substances, in the injector port for GC-MS analysis. This technique was a useful tool for the differentiation of 11 "Terrincho" ewe cheeses, all taken from the same cheesemaking season with 30 days of ripening but from three different farmhouses, according to their volatile fraction. Results obtained were statistically treated by categorical principal component analysis. Subsequently, 49.15% of the variation in data was due to the first dimension (k = 12.7) and the second dimension (k = 8.88) accounted for 34.2% of the total information. Volatile profiles among samples indicated cheese group separation according to farmhouse of production.

Animals↗
PubMed1999

Analysis of volatile organic compounds in human urine by headspace gas chromatography-mass spectrometry with a multipurpose sampler.

A multipurpose sampler (Gerstel MPS), designed for liquid large volume, gaseous and headspace samples was used for the GC-MS analysis of organic volatiles in human urine. Headspace sampling with a volume-, temperature- and speed-controlled gas-tight syringe was combined with a temperature-controlled cold injection system (CIS) for cold trapping, enrichment and focusing of analytes. Regular 2-ml GC vials filled with 1 ml acidified urine were used as headspace sampling vials. A 100-vial autosampler tray was equipped with an additional temperature and heating time controlled "preheating station" for five vials. Profiles of organic volatiles in human urine were determined and 34 components identified. Trimethylamine (TMA) and 4-heptanone as two metabolites of medical interest were quantified. Calibration curves and intra assay imprecision for 4-heptanone concentrations in the range of 40 to 800 ng/ml showed a correlation coefficient of r = 0.9980 and a relative standard deviation (RSD) between 3.0 and 3.4%. Calibration curves and intra-assay imprecision for TMA concentrations in the range of medical interest from 0.5 to 20 micrograms/ml showed a correlation coefficient of r = 0.9968 and a RSD between 4.1 and 6.8%. The high practicability of the multipurpose sampler for both gaseous and liquid samples together with the here shown good reproducibility and sensitivity make this single CIS-GC-MS system very attractive for routine clinical use in metabolic profiling of organic volatiles (headspace) and non-volatiles (liquid).

Gas Chromatography-Mass Spectrometry↗
PubMed2001

The ecological and taxonomic importance of flower volatiles of Clusia species (Guttiferae).

The chemical composition of floral volatiles of sixteen species of Clusia (Guttiferae) belonging to four different taxonomic sections of the genus was investigated. The volatiles were extracted from fresh petals by microhydrodistillation and analysed by GC/MS. The composition of the volatiles was in part, but not always, related to the taxonomic position of the species, and to a minor extent to the type of pollinator observed on the flowers as revealed by clustering analysis. The composition of the volatile components of female and male flowers belonging to the same species (C. grandiflora, C. lanceolata, C. paralicola, C. parviflora and C. spiritu-sanctensis) was found to be almost identical. Field bioassays showed the petal extracts to be attractive to pollinating bees.

Chromatography, Gas↗
PubMed1994

Volatile constituents of wild and in vitro cultivated Gloeophyllum odoratum.

The brown-rot fungus Gloeophyllum odoratum was collected from spruce stumps in southern Finland. The volatiles in the fruiting body and fungal cultures grown in malt extract and liquid medium were investigated. Chitin, chitosan and D-(+)-glucosamine at a concentration of 450 mgl-1 medium were used as elicitors. Chitosan completely inhibited growth in the solid medium. The main volatile(s) according to GC and GC-MS analysis were either linalool, citronellol, geraniol and methyl p-methoxyphenylacetate or drimenol depending on the culture type and elicitor. The composition of volatiles in the natural fungus differed slightly from that of the cultivated fungus since the major compound was methyl p-methoxyphenylacetate. The volatile oils were toxic to larvae of the brine shrimp, Artemia salina, indicating that they may possess insecticidal and cytotoxic activity.

Animals↗
PubMed2003

Volatile compounds from leaf-buds of Populus nigra L (Salicaceae).

Volatile components from fresh and air-dried leaf-buds of Populus nigra L. (Salicaceae) were isolated by Likens-Nickerson apparatus and analyzed using GC/MS. Forty-eight components (ca. 95% of the total isolate) were identified among black poplar bud volatiles. Sesquiterpene alcohols beta-eudesmol and alpha-eudesmol represented 26.3-28.7% of the oil. Other major sesquiterpene compounds were gamma-selinene (7.6-8.8%), delta-cadinene (7.8-8.6%), alpha-elemene (3.3-5.2%) and gamma-cadinene (3.9-4.2%). Hemiterpenes were also identified (2.2-7.6%). Monoterpenes were present in low percentages (1.6-5.7%). Aliphatic and aromatic alcohols, carbonyl compounds and aliphatic acids were identified among non-terpene volatiles (9.8-13.5%). The fresh buds contained 0.27% and dried 0.12% essential oil. Air-drying moderately effected the volatiles qualitative and quantitative composition.

Gas Chromatography-Mass Spectrometry↗
PubMed2003

Effects of temperature on the production of hydrogen peroxide and volatile halocarbons by brackish-water algae.

Marine algae produce volatile halocarbons, which have an ozone-depleting potential. The formation of these compounds is thought to be related to oxidative stress, involving H2O2 and algal peroxidases. In our study we found strong correlations between the releases of H2O2 and brominated and some iodinated compounds to the seawater medium, but no such correlation was found for CHCl3, suggesting the involvement of other formation mechanisms as well. Little is known about the effects of environmental factors on the production of volatile halocarbons by algae and in the present study we focused on the influence of temperature. Algae were sampled in an area of the brackish Baltic Sea that receives thermal discharge, allowing us to collect specimens of the same species that were adapted to different field temperature regimes. We exposed six algal species (the diatom Pleurosira laevis, the brown alga Fucus vesiculosus and four filamentous green algae, Cladophora glomerata, Enteromorpha ahlneriana, E. flexuosa and E. intestinalis) to temperature changes of 0-11 degrees C under high irradiation to invoke oxidative stress. The production rates, as well as the quantitative composition of 16 volatile halocarbons, were strongly species-dependent and different types of responses to temperature were recorded. However, no response patterns to temperature change were found that were consistent for all species or for all halocarbons. We conclude that the production of certain halocarbons may increase with temperature in certain algal species, but that the amount and composition of the volatile halocarbons released by algal communities are probably more affected by temperature-associated species shifts. These results may have implications for climatic change scenarios.

Eukaryota↗
PubMed1999

Volatility of propoxur from different surface materials commonly found in homes.

The purpose of this study was to determine the volatilization rates of propoxur from different surface materials commonly found in homes, and to conduct field measurements under ventilated and non-ventilated conditions. Since it is known that temperature, humidity and constant air flow most significantly affect volatility, various surface materials were sprayed using a constant amount of propoxur under the controlled conditions of an exposure chamber. Acetonitrile was used to desorb both XAD-2 resin that collected airborne propoxur and surface materials containing propoxur residue. HPLC was used to analyze propoxur concentrations. Based on multiple regression models, temperature most significantly affected volatility, followed by humidity. Volatilization rates of propoxur were highest from quartz surfaces and lowest from glass. Interaction was most readily found on glass surfaces based on humidity-air flow and humidity-temperature factors. In field applications, propoxur was sprayed in a room under two conditions with ventilation and without in order to measure the concentrations of propoxur in the air and on a quartz surface. Findings showed both airborne and settled concentrations peaked after a half hour then decreased under both conditions, both more sharply in the ventilated room. Under both conditions, no propoxur was detected on the quartz surface after three and a half hours but airborne concentrations remained detectable after thirty-three and one half hours. We conclude that to maintain good air quality, ventilation is important and special care must be taken when spraying insecticides on different surfaces.

Air Pollution, Indoor↗
PubMed2000

Capacity of mercury volatilization by mer (from Escherichia coli) and glutathione S-transferase (from Schistosoma mansoni) genes cloned in Escherichia coli.

A study was carried out to evaluate the capacity for mercury volatilization by genetically engineered strains that express the mer and glutathione S-transferase genes from Escherichia coli and Schistosoma mansoni, respectively. This method enabled strains containing simultaneously mer and glutathione S-transferase genes to grow in high concentrations of mercuric chloride (30 microg/ml) and to volatilize part of the mercury (248 microg/g cell dry wt.) present in the culture medium, while strains bearing only a single gene, did not have the same behavior. Up to 70% of the total mercury of bacterial volatilization occurred in the first 4 h. Although the findings were preliminary, the genetically engineered strain containing simultaneously the mer and glutathione S-transferase genes show a great potential for bioremediation. It may be used in a closed system to remove by volatilization, and recover mercury (Hg0) from contaminated effluents, such as industrial effluent, for instance.

Animals↗
PubMed2000

The measurement of volatile constituents in Foray 48B, an insecticide prepared from Bacillus thuringiensis var. kurstaki.

Foray 48B, an insecticide prepared from Bacillus thuringiensis var. kurstaki (Btk), has been used for many years to combat infestations of Gypsy moths. Foray 48B also contains a large number of 'inert ingredients' which are not disclosed by the manufacturer. Gypsy moths usually enter the country through marine- and airports in close proximity to urban areas, which consequently need to be sprayed. The population affected often demands more detailed information than what is available including the potential presence of volatile organic agents which could be released during spraying, posing a potential health hazard. Four different methods were investigated using GC/mass spectrometry regarding their ability to capture volatile agents associated with Foray 48B. It was found that solid phase micro-extraction was most efficient in capturing volatile agents from the head-space of Foray 48B. Separate trials using 95:5% ethanol/isopropanol mixture and toluene in an impinger configuration were much less efficient. Standard techniques using activated charcoal tubes in the laboratory setting as well as in a field trial did not capture any compounds. It was concluded that the volatile agents associated with Foray 48B did not appear to constitute a significant health hazard and no one agent was a likely candidate to serve as a tracer for Foray 48B exposure.

Bacillus thuringiensis↗
PubMed2001

Transport of volatile compounds in porous media in the presence of a trapped gas phase.

The presence of an immobile gaseous phase in an otherwise-saturated porous medium affects the transport of volatile compounds. The linear theory of partitioning tracers suggests that a volatile tracer introduced into such a system should be retarded with a constant retardation factor. Using high concentrations, however, the saturation of the gaseous phase will change as an effect of the tracer test itself. Competitive gas transfer among all volatile compounds and the change of saturation may lead to tracer concentrations that are temporarily higher than those injected. We analyze the system in the framework of the coherence theory by Helfferich [Soc. Pet. Eng. J. 21 (1) (1981) 51]. The governing equations are formulated as functions of total concentration, i.e., the mass of solutes in all phases per pore volume. Neglecting dispersion and mass-transfer kinetics, we derive the characteristic form of the resulting system of hyperbolic equations. In a system with N volatile compounds, a variation of the concentrations splits up into N waves, each traveling with its own characteristic velocity. If the presence of a gaseous phase is sustained, one wave will be a standing one. We perform numerical model calculations for tracers with various Henry's law coefficients and show that the results agree with the semi-analytical solution obtained by coherence theory.

Gases↗
PubMed2001

Headspace solid-phase microextraction profiling of volatile compounds in urine: application to metabolic investigations.

Volatile compounds contribute substantially to the metabolic pool in man. Their analysis in body fluids is problematic. We investigated headspace solid-phase microextraction (HS-SPME) with Carboxen-polydimethylsiloxane fibres and gas chromatography-mass spectrometry for profiling urinary volatile components. These fibres were more sensitive for very volatile and sulfur compounds than three other phases tested. We detected a wide range of compounds in normal urine at acid and alkaline pH. Profiles presented for five individuals with metabolic disturbances demonstrate abnormal accumulation of sulfur compounds, fatty acids and plasticisers. HS-SPME can complement profiling of non-volatile compounds in metabolic investigations and could be a useful extension of the diagnostic repertoire.

Adult↗
PubMed2001

In vitro study on the transfer of volatile oil components.

The following volatile oils were tested in vitro: chamomile (Matricaria recutica L.), peppermint (Mentha piperita L.) and sage (Salvia officinalis L.) to obtain information on which components of volatile oils or minerals are able to pass through the membranes under different conditions. The transfer of chamomile and peppermint oil from aqueous volatile oil to the stomach (pH=1.1) and then to the plasma (pH=7.5) was studied, and the transfer of sage oil through the skin (from pH=5.5 to pH=7.5) was examined. The transfer of some components was more favorable than that of others. The transfer of chamomile oil was faster to buffer pH=1.1 than from buffer pH=1.1 to buffer pH=7.5 and most of the components, except for chamazulene, passed through the membranes. In the case of peppermint the components went through the membranes in the first 15 min although the main components mostly remained in the initial solution. The sage oil transferred showed the same characteristics as the starting oil. A small amount of metal present in the volatile oils also passed through the membranes. The transfer of metals varied, depending on the time, type of the oil, metal quality and the conditions applied.

Hydrogen-Ion Concentration↗
PubMed2002

Evaluation of volatile compounds in different types of ghee using direct injection with gas chromatography-mass spectrometry.

Desi ghee (DG) was prepared from fermented cream followed by heat clarification (desi method) in the laboratory and butter oil (BO) was prepared from fresh butter by melting and centrifugation. Fresh samples of three brands of industrial ghee (IG-1, IG-2, IG-3) were collected from the local market. Volatile compounds of desi and industrial ghee and butter oil were isolated and concentrated using direct injection and cryofocussing techniques; separation and identification was by Gas Chromatography Mass Spectrometry (GCMS). A maximum of 36 compounds were detected in desi ghee whereas compounds detected in three industrial ghee samples varied from 22-29. The lowest number of compounds (16) was detected in butter oil. Of the identified compounds, maltol, 5-hydroxymethyl furfuraldehyde, dihydrodihydroxypyranone, 1,3-butanediol and 1-octanol were identified only in desi ghee volatiles. The concentration of acetic acid was found to be remarkably higher in desi ghee volatiles than in industrial ghee. Also the levels of identified fatty acids, methyl ketones, aldehydes, lactones and alcohols were high in desi ghee volatiles compared with industrial ghee and butter oil. In total, 62 compounds were detected, which included 6 aldehydes, 12 ketones, 8 each of fatty acids, alcohols and lactones, 4 each of esters and hydrocarbons or other compounds, and 12 compounds remained unidentified.

Alcohols↗
PubMedDate not supplied

Modulated release of a volatile compound from starch matrixes via enzymatically controlled degradation.

The release of a model volatile (diacetyl) from a system based on a starch matrix, in which the volatile is dispersed, was studied. Kneading was used to obtain a homogeneous mixture (melt) composed of starch, glycerol alpha-amylase, and diacetyl. Samples were then ground to powders. When the starch powders were exposed to 30% relative humidity (RH) at 20 degreesC, no degradation of the starch matrix occurred. The samples only showed an initial burst release of diacetyl (around 10% of the loaded dose), whereas the remaining amount of diacetyl was not released, most likely due to the glassy character of the matrix and the low solubility of diacetyl in the matrix. However, when the samples were incubated at 90% RH, due to the uptake of moisture by the particles full release of the entrapped volatile occurred. The release of diacetyl from the matrix without enzyme followed first-order kinetics and, as expected, the release rate increased with decreasing particle size. Due to absorption of water, the enzyme became active and starch degradation occurred. The initial release of diacetyl from amylase-containing matrixes followed first-order kinetics as well. However, once the matrix was degraded to a certain extent, the particles collapsed, which was associated with concomitant rapid increase in release. The time at which the particle collapse occurred decreased with increasing enzyme concentration in the matrix. In conclusion, it is demonstrated that the release of a volatile from starch matrixes can be modulated both by the amount of coencapsulated matrix-degrading enzyme and by the humidity of the environment.

Absorption↗
PubMed2002

Detection of volatile organometal chloride species in model atmosphere above seawater and sediment.

The principal route for release of organometallic species into the atmosphere is currently considered to be the biological or chemical formation of saturated volatile compounds such as dimethylmercury, metal hydrides, etc. Model experiments conducted in our laboratory pointto the release of extremely toxic, volatile organotin, -lead, -mercury, and -arsenic species that have been detected as the chlorides in the gas phase above seawater and sediment mixtures. As the sediment was sterilized prior to the analytical study, any bioformation of volatile metal species was excluded. The most probable account of these observations is the naturally occurring formation of metal chlorides, fueled by the abundance of chloride ion (or other halides) present in seawater and many other natural environments. This raises the suggestion that the release of toxic trace elements to the atmosphere by environmental processes may be seriously underestimated. A conservative projection, based on laboratory data, suggests that the emission of butyltin into the atmosphere may reach as high as 150 ng/m2 of water/yr from a polluted marine environment, suggesting a very significant level of release of butyltin from seawater at the global level. For the sampling and determination of volatile metal species, solid-phase microextraction combined with inductively coupled plasma time-of-flight mass spectrometry has been used. This new analytical system is capable of detection of semivolatile, thermally unstable compounds such as the class encompassing metal halide species.

Biotransformation↗
PubMed2003

Sea breeze modulated volatilization of polycyclic aromatic hydrocarbons from the Masnou Harbor (NW Mediterranean Sea).

Harbors, marinas, and coastal environments are impacted by important pollutant loadings, particularly of polycyclic aromatic hydrocarbons (PAHs). Air-water exchange is an important process driving the environmental fate of organic pollutants in aquatic environments. However, its relevance as a factor affecting the environmental fate of pollutants from harbor sediments and waters has not been properly assessed, so far, except for few coastal environments. The objective of this study is to quantify the importance of volatilization losses of PAHs from harbor sediments and waters and to study the potential role of sea breeze as a modulator of air-water exchange in coastal environments. The results show that volatilization fluxes from a medium size marina located in the NW Mediterranean sea are relatively high in comparison to those observed in other aquatic systems, particularly for the low molecular weight (MW) compounds. This is consistent with PAHs profiles observed in harbor sediments, which are depleted by the lower MW hydrocarbons. Therefore, volatilization is an important loss of low MW PAHs such as phenanthrene, methyl phenanthrene, dibenzothiophene, etc. Indeed, these PAHs have a residence time of few days in the harbor waters and sediments. Finally, the diurnal trends in volatilization fluxes mimics that of the sea breeze influenced wind speed. These results show the important role that the diurnal sea breeze exerts on the environmental fate of pollutants such as PAHs in coastal environments as a modulator of air-water exchange and as a potential driver of transport of pollutants between adjacent coastal and terrestrial environments.

Air Pollutants↗