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PubMed2004

A direct quantitative analysis method for monitoring biogenic volatile organic compounds released from leaves of Pelargonium hortorum in situ.

A direct quantitative method is presented that is based upon the use of multiple headspace solid phase microextraction (HS-SPME) to monitor biogenic volatile organic compounds (BVOCs) released from a living leaf of Pelargonium hortorum in situ. Seventeen BVOCs were detected by GC-MS after a single SPME extraction using a CAR/DVB/PDMS fibre. An internal standard was employed to determine the absolute amounts of seven terpenoid compounds released from a P. hortorum leaf. The quantitative analysis was performed over two days, with extraction preformed for 20 min every 3 h. The amount of volatiles extracted varied with the time of day, with two maxima recorded at 14:00 (day 1) and 17:00 (day 2), corresponding to 236 and 277 ng of the seven terpenoids recorded, respectively. These results indicate that multiple HS-SPME in combination with an internal standard is a simple, quick, and quantitative technique for analysising BVOC emissions from a live plant sample.

Calibration↗
PubMed2001

Species-specific isotope-ratio measurements of volatile tin and antimony compounds using capillary GC-ICP-time-of-flight MS.

The analytical performance of an axial inductively-coupled-plasma time-of-flight mass spectrometer (ICP-TOFMS) as a detector for fast transient chromatographic signals resulting from the coupling to capillary gas chromatography (CGC) was investigated. A cryotrapping GC-ICP-TOFMS method for the determination of volatile metal(loid) compounds (VOMs) in gases was used and the suitability of the TOF mass analyzer for multielemental speciation analysis and multi-isotope ratio determinations was studied in terms of accuracy and precision. Isotope ratios 118Sn/120Sn and 121Sb/123Sb have been determined in in-house gas standard atmospheres in Tedlar bags at two different levels (100 pg and 1 ng) for different elemental species (SnH4, MeSnH3, Me2SnH2, Me3SnH, BuSnH3, SbH3, and MeSbH2). A limitation arising from counting statistics in both detection modes could be shown. A solution containing rhodium (10 ng mL(-1)) and cadmium (40 ng mL(-1)) was introduced simultaneously to the GC outlet. Rhodium acts as a continuous internal standard and Cd is used for mass-bias correction (by measuring the 111Cd/113Cd ratio). The detection system in both pulse counting and analog mode was examined. The best attainable precision was established for Me2SnH2 (analog mode, 12 replicates, 1 ng, RSD 0.34%, accuracy 0.31%) whereas most other species ranged between 0.4 and 0.5% RSD if higher concentrations were used. The limitations of the pulse counting system are clearly seen, with peak heights of more than 2000 counts reaching saturation (for an integration time of 100 ms), which reduces the accuracy of isotope ratio determinations. A dozen VOM could be detected in an aged landfill gas sample; several unidentified Sn compounds were present. Although their isotope ratios are within the confidence value of the standards, it is not yet clear if the acquired precision is good enough to identify isotopic fractionation of metal(loid)s through biovolatilization processes. With the precision achieved, the combination of cryotrapping GC and ICP-TOFMS is a powerful tool for monitoring volatile multi-element species in multi-tracer experiments and isotope dilution methodology.

Antimony↗
PubMed2001

Detection of volatile organic peroxides in indoor air.

A supercritical fluid extraction cell filled with adsorbent (Carbotrap and Carbotrap C) was used directly as a sampling tube to enrich volatile organic compounds in air. After sampling, the analytes were extracted by supercritical fluid CO2 with methanol as modifier. Collected organic peroxides were then determined by a RP-HPLC method developed and validated previously using post-column derivatization and fluorescence detection. Some volatile organic peroxides were found in indoor air in a new car and a newly decorated kitchen in the lower microg m(-3) range. tert-Butyl perbenzoate, di-tert-butyl peroxide, and tert-butylcumyl peroxide could be identified.

Air Pollution, Indoor↗
PubMed2000

Biodegradability of volatile hydrocarbons of gasoline.

The biodegradability under aerobic conditions of volatile hydrocarbons (4-6 carbons) contained in gasoline and consisting of n-alkanes, iso-alkanes, cycloalkanes and alkenes, was investigated. Activated sludge was used as the reference microflora. The biodegradation test involved the degradation of the volatile fraction of gasoline in closed flasks under optimal conditions. The kinetics of biodegradation was monitored by CO2 production. Final degradation was determined by gas chromatographic analysis of all measurable hydrocarbons (12 compounds) in the mixture after sampling the headspace of the flasks. The degradation of individual hydrocarbons was also studied with the same methodology. When incubated individually, all hydrocarbons used as carbon sources, except 2,2-dimethylbutane and 2,3-dimethylbutane, were completely consumed in 30 days or less with different velocities and initial lag periods. When incubated together as constituents of the light gasoline fraction, all hydrocarbons were metabolised, often with higher velocities than for individual compounds. Cometabolism was involved in the degradation of dimethyl isoalkanes.

Biodegradation, Environmental↗
PubMed2002

Host plant volatiles synergize responses of sex pheromone-specific olfactory receptor neurons in male Helicoverpa zea.

Single-cell electrophysiological recordings were obtained from olfactory receptor neurons in antennal trichoid sensilla of male corn earworm, Helicoverpa zea. Spontaneous activity of the neuron specific for the major component ( Z)-11-hexadecenal, the conspecific female-emitted sex pheromone, was not affected by exposure to host plant volatiles. However, stimulations with binary mixtures of a threshold dosage of the pheromone component and increasing dosages of either linalool or ( Z)-3-hexenol significantly synergized the pheromone-specific neuron's firing rates compared with responses to the major pheromone component alone. Cross-adaptation studies confirmed that the enhanced impulses originated from the pheromone-component-tuned neuron. Because plant volatiles do not stimulate the pheromone-specific neuron when presented alone, the pheromone plus host odor blend would be interpreted as containing more pheromone than it actually does when processed by the pheromone-processing portion of the antennal lobe.

Action Potentials↗
PubMed2005

Juggling with volatiles: exposure of perfumes by displaying male orchid bees.

Male orchid bees (Euglossini) pollinate 10% of the neotropical orchid flora while collecting floral scents, which they store and accumulate in hind tibial pouches. The purpose of these fragrances is unclear, as is the context, timing and mechanism of their possible exposure. Here we show for the first time that males expose and relocate their fragrances during courtship display. We present high-speed video analyses revealing an intricate and repetitive leg movement performed by displaying male Euglossa cognata. The behavior involves several morphological structures of hitherto unknown function and suggests transfer of substances from the hind tibia to a contralateral mid-tibial tuft of hairs. Body-side-specific fluorescent dye application and consecutive detection of signals on males after display confirmed this transfer. Deposited on the mid-tibial tufts, the fragrances are ideally placed in order to become ventilated by jugal combs on the wing bases, as previously suggested by Bembé (in Apidologie 35:288-291, 2004). Being clearly distinct from motor patterns involved in fragrance collection, the described movement is continuously performed by displaying males, suggesting an equally continuous exposure of volatiles. Although the findings strengthen, the view that the volatiles serve as attractants in the context of mating behavior, the signal addressee, conspecific males or females, has yet to be found.

Animal Communication↗
PubMed2001

Detection of fruit- and flower-emitted volatiles by olfactory receptor neurons in the polyphagous fruit chafer Pachnoda marginata (Coleoptera: Cetoniinae).

Olfactory receptor neurons on the antennae of the African fruit chafer species Pachnoda marginata (Coleoptera: Scarabaeidae) were examined through extensive use of gas chromatography linked with electrophysiological recordings from single olfactory receptor neurons. Contacted neurons were stimulated with a large number of extracted volatiles from 22 different fruits and with 64 synthetic plant compounds. Extracted fruit volatiles were identified using linked gas chromatography-mass spectrometry. In total, 48 different odor compounds were found to elicit responses. Analysis of the response spectra of the contacted neurons (n = 232) revealed the presence of 28 classes of receptor neurons. The neurons exhibited strong selectivity as well as high sensitivity. Eleven of the identified classes were selectively activated by single compounds, while the remaining were activated by 2-6 compounds. Several receptor neurons that were activated by more than one compound responded to compounds sharing basic structural similarities. The results support the growing hypothesis that a significant proportion of plant-odor receptor neurons in insects are highly sensitive and selective for single odors.

Animals↗
PubMed2000

Influence of volatile and intravenous anesthetics on the threshold of the acoustically evoked stapedius reflex.

The influence of volatile and intravenous anesthetics on the threshold of the acoustically evoked stapedius reflex (SR) was studied prospectively in 45 patients undergoing elective ENT surgical procedures. After premedication with flunitrazepam the patients were randomly assigned to one of nine groups. Group I: 70% nitrous oxide (N2O) in oxygen (O2); Groups II-VII: induction of anesthesia with intravenous thiopental, followed by mask inhalation with 100% O2 and 1.13% halothane (Group II), 2.52% enflurane (Group III) or 1.73% isoflurane (Group IV); or 70% N2O in oxygen, and 0.44% halothane (Group V), 0.86% enflurane (Group VI) or 0.75% isoflurane (Group VII): Group VIII: intravenous midazolam and ketamine; and Group IX: intravenous midazolam and alfentanil. Tympanometry and ipsilateral and contralateral SR measurements were performed when the effects of the anesthetics had achieved a steady state. Flunitrazepam raised the SR threshold only slightly. Substances applied during inhalation anesthesia either markedly increased the threshold contralaterally more than ipsilaterally (thiopental, N2O), or suppressed the reflex completely (thiopental, all volatile anesthetics with or without N2O). Under intravenous anesthesia the reflex was always present. The midazolam-ketamine combination influenced the threshold bilaterally only slightly, while the midazolam-alfentanil combination led to a pronounced, contralaterally significant elevation of the threshold. Based on its minimal influence on the SR threshold, flunitrazepam is especially suitable for sedation and the midazolam-ketamine combination for anesthesia in audiological diagnostic procedures.

Acoustic Impedance Tests↗
PubMed2002

Metabolic profiling of oxylipins in germinating cucumber seedlings--lipoxygenase-dependent degradation of triacylglycerols and biosynthesis of volatile aldehydes.

A particular isoform of lipoxygenase (LOX) localized on lipid bodies was shown by earlier investigations to play a role in initiating the mobilization of triacylglycerols during seed germination. Here, further physiological functions of LOXs within whole cotyledons of cucumber (Cucumis sativus L.) were analyzed by measuring the endogenous amounts of LOX-derived products. The lipid-body LOX-derived esterified (13 S)-hydroperoxy linoleic acid was the dominant metabolite of the LOX pathway in this tissue. It accumulated to about 14 micromol/g fresh weight, which represented about 6% of the total amount of linoleic acid in cotyledons. This LOX product was not only reduced to its hydroxy derivative, leading to degradation by beta-oxidation, but alternatively it was metabolized by fatty acid hydroperoxide lyase leading to formation of hexanal as well. Furthermore, the activities of LOX forms metabolizing linolenic acid were detected by measuring the accumulation of volatile aldehydes and the allene oxide synthase-derived metabolite jasmonic acid. The first evidence is presented for an involvement of a lipid-body LOX form in the production of volatile aldehydes.

Aldehydes↗
PubMed2002

Functional identification of AtTPS03 as (E)-beta-ocimene synthase: a monoterpene synthase catalyzing jasmonate- and wound-induced volatile formation in Arabidopsis thaliana.

(E)-beta-Ocimene is one of the most commonly found monoterpenes of the volatile blends that are emitted from leaves in response to damage by herbivores or mechanical wounding. (E)-beta-Ocimene is also a component of many floral scents. Airborne (E)-beta-ocimene emitted from plants can serve as a chemical cue for the attraction of parasitoids or predators of plant herbivores and also as an attractant for pollinating insects. Furthermore, exposure of plants to (E)-beta-ocimene can activate defense gene expression. In this paper, we describe cDNA cloning and functional characterization of a gene encoding a highly specialized (E)-beta-ocimene synthase, AtTPS03, from Arabidopsis thaliana (L.) Heynh. AtTPS03 was identified as a member of the large AtTPS gene family of putative terpene synthases. A cDNA for AtTPS03 was expressed in Escherichia coli and the enzyme function identified in vitro. The A. thaliana (E)-beta-ocimene synthase produces almost exclusively (E)-beta-ocimene (94%) with minor amounts of the related acyclic monoterpenes (Z)-beta-ocimene (4%) and myrcene (2%). Transcripts for AtTPS03 were up-regulated in leaves of Arabidopsis in response to mechanical wounding and treatment with jasmonic acid, concurrent with induced emission of (E)-beta-ocimene. AtTPS03 provides an important gene for probing plant-insect and possibly plant-plant interactions mediated by terpenoid volatiles.

Acyclic Monoterpenes↗
PubMed2006

Volatiles modulate the development of plant pathogenic rust fungi.

Rust fungi are obligate biotrophic pathogens that differentiate a series of specialized cells to establish infection. One of these cells, the haustorium, which serves to absorb nutrients from living host cells, normally develops only in planta. Here, we show that the rust fungus Uromyces fabae (Pers.) Schroet. stimulates volatile emission of its host, broad bean (Vicia faba L.). Volatiles were identified and shown to be perceived by the fungus in in vitro assays that excluded the host. Three of them, nonanal, decanal, and hexenyl acetate promoted the development of haustoria on artificial membranes. In contrast, the terpenoid farnesyl acetate suppressed this differentiation. In assays using whole plants, farnesyl acetate reduced rust disease not only on broad bean but also on several cereals and legumes including soybean. This natural substance was effective against all rusts tested when directly applied to the host. This demonstrated that farnesyl acetate may serve as a powerful novel tool to combat rust fungi including Phakopsora pachyrhizi that currently threatens the production of soybeans world-wide.

Fungi↗
PubMed2001

X-ray absorption spectroscopy study shows that the rapid selenium volatilizer, pickleweed (Salicornia bigelovii Torr.), reduces selenate to organic forms without the aid of microbes.

In many plant species, selenium (Se) volatilization is limited by the reduction of selenate and its chemical conversion to organic Se compounds, a process that may be facilitated by rhizosphere microbes. This study was conducted to determine if pickleweed (Salicornia bigelovii Torr.), which is characterized by having high rates of Se volatilization from selenate, is able to reduce selenate into organic forms of Se axenically, or whether it requires the presence of microbes. X-ray absorption spectroscopy analysis showed that shoots and roots of pickleweed plants supplied with 50 microM selenate accumulated Se predominantly in organic Se forms (about 65-75% of the total accumulated Se), regardless of whether the plants were grown axenically or in the presence of microbes. The results suggest that, unlike other species for which selenate reduction appears to be rate limiting. e.g. Indian mustard (Brassica juncea L.) and broccoli (Brassica oleracea L.), pickleweed is unusual in that it has an enhanced capacity to reduce selenate to organic forms that is independent of the presence of rhizosphere microbes.

Chenopodiaceae↗
PubMed2002

Aerial short-range dispersion of volatilized pesticides from an area source.

Owing to legal provisions, pesticides have to be applied in such a way that there is no unacceptable influence on human health and the environment at nearby non-target areas. In order to quantify their concentration over and downwind of agricultural target plots of 0.5-1 ha, covered by winter wheat and winter barely, the pesticides lindane, parathion and pirimicarb were applied. Over these plots the post-application volatilization rates of the pesticides were estimated indirectly from vertical concentration, wind and temperature profile measurements using the aerodynamic gradient technique. Philip's advection model was applied to take non-favourable fetch conditions into account. In addition, at a height of 1.6 m downwind of the area source, measurements of the horizontal concentration profile were made up to a distance of about 250 m at roughly 50-m intervals. The monitoring started immediately after spraying in the morning and continued for about 8-10 h, thus providing a worst-case situation because volatilization, and therefore pesticide concentration in the atmospheric surface layer, is then strongest. The concentration of the airborne pesticides over the downwind non-target area was also calculated by Philip's advection model. By using the Nash-Sutcliffe relative-difference measure between observed and calculated concentrations, a goodness-of-fit of 0.97 was obtained over the downwind non-target area, indicating that the Philip model is well suited for dispersion estimates in the near-field range.

Agriculture↗
PubMed2003

Branched chain amino acids as source of specific branched chain volatile fatty acids during the fermentation process of fish sauce.

The source of the formation of branched chain volatile fatty acids (VFA) in fish sauce was investigated. Certain branched VFA were derived from the degradation of specific amino acids as iso-butyric acid from valine and iso-valeric acid from leucine. Short and long straight chain VFA were significantly higher in the linoleic acid added sample than in the control but did not significantly bring changes to the branched chain VFA. It is suggested that straight chain VFA developed from fish fats. Alanine and isoleucine did not have a clear influence on the production of volatile fatty acids.

Amino Acids, Branched-Chain↗
PubMed2006

Estragole (4-allylanisole) is the primary compound in volatiles emitted from the male and female cones of Cycas revoluta.

The genus Cycas (Cycadaceae; gymnosperm) have circumstantially been considered to be wind-pollinated. The cones of Cycas revoluta Thunb., however, emit a strong unpleasant odor. The chemical profiles of floral scents often correlate with various pollination modes (pollinators). We collected and analyzed the volatiles emitted from male and female cones of C. revoluta native to Iriomote and Yonaguni Islands, Japan. The analyses indicated that estragole (4-allylanisole) dominated in the volatiles (67.0-92.7%), with small amounts of other benzenoids, e.g., anethole, methyl salicylate, methyl eugenol, and ethyl benzoate. Several fatty acid esters were also detected in the samples from Iriomote Island. The function of estragole in the reproductive biology of C. revoluta is discussed.

Allylbenzene Derivatives↗
PubMed2005

Dynamic modeling of the ratio volatile fatty acids/bicarbonate alkalinity in a UASB reactor for potato processing wastewater treatment.

In this work, dynamic mathematical model for the prediction of the operational parameter volatile fatty acids/bicarbonate alkalinity (VFA/ALK) in a UASB reactor was developed. The dynamic modeling technique was applied successfully to a two-year data record from an industrial wastewater treatment plant of a potato processing industry. The technique used included regression analysis by residuals. Seventeen parameters were examined including the following: wastewater's flow rate, reactor's temperature and pH, total and soluble influent COD, wastewater's temperature and pH, total and soluble effluent COD, volatile fatty acids, alkalinity, biogas production rate and each parameter with a time lag of up to 10 days. Finally, after all parameters and all time lag trials the best fitted model was developed. The model's adequacy was checked by chi2 test for a data record of the same UASB reactor but at a different time period and proved to be satisfactory. Additionally, the model's ability to predict and to control the plant's operation via VFA/ALK was examined. Through this model, in contrary to steady state models, various aspects of the process can be enlighten, such as the fact that the hydrolysis of starch requires at least a resident time of seven days.

Bicarbonates↗
PubMed2005

Antennal and behavioral responses of grapevine moth Lobesia botrana females to volatiles from grapevine.

Grapevine moth Lobesia botrana is the economically most important insect of grapevine Vitis vinifera in Europe. Flower buds, flowers, and green berries of Chardonnay grapevine are known to attract L. botrana for oviposition. The volatile compounds collected from these phenological stages were studied by gas chromatography-mass spectrometry, and the antennal response of L. botrana females to these headspace collections was recorded by gas chromatography-electroantennography. The compounds found in all phenological stages, which consistently elicited a strong antennal response, were pentadecane, nonanal, and alpha-farnesene. In a wind tunnel, gravid L. botrana females flew upwind to green grapes, as well as to headspace collections from these berries released by a piezoelectric sprayer release device. However, no females landed at the source of headspace volatiles, possibly due to inappropriate concentrations or biased ratios of compounds in the headspace extracts.

Animals↗
PubMed2005

Effects of mechanical wounding on essential oil composition and emission of volatiles from Minthostachys mollis.

Plant tissues may show chemical changes following damage. This possibility was analyzed for Minthostachys mollis, a Lamiaceae native to Central Argentina with medicinal and aromatic uses in the region. Effects of mechanical damage on its two dominant monoterpenes, pulegone and menthone, were analyzed by perforating M. mollis leaves and then assessing essential oil composition at 24, 48, and 120 hr; emission of volatiles was also measured 24 and 48 hr after wounding. Mechanical damage resulted in an increase of pulegone and menthone concentration in M. mollis essential oil during the first 24 hr. These changes did not occur in the adjacent undamaged leaves, suggesting a lack of systemic response. Postwounding changes in the volatiles released from M. mollis damaged leaves were also detected, most noticeably showing an increase in the emission of pulegone. Inducible chemical changes in aromatic plants might be common and widespread, affecting the specific compounds on which commercial exploitation is based.

Animals↗