Volatiles produced by the mycophagous soil bacterium Collimonas
Garbeva, P. ; Hordijk, C. ; Gerards, S. ; Boer, W. de - \ 2014
FEMS microbiology ecology 87 (2014)3. - ISSN 0168-6496 - p. 639 - 649.
community composition - organic-compounds - genus collimonas - fungal hyphae - bulk soil - sp nov. - growth - fungivorans - rhizosphere - fungistasis
It is increasingly recognized that volatile organic compounds play an import role during interactions between soil microorganisms. Here, we examined the possible involvement of volatiles in the interaction of Collimonas bacteria with soil fungi. The genus Collimonas is known for its ability to grow at the expense of living fungi (mycophagy), and antifungal volatiles may contribute to the attack of fungi by these bacteria. We analyzed the composition of volatiles produced by Collimonas on agar under different nutrient conditions and studied the effect on fungal growth. The volatiles had a negative effect on the growth of a broad spectrum of fungal species. Collimonas bacteria did also produce volatiles in sand microcosms supplied with artificial root exudates. The production of volatiles in sand microcosms was enhanced by the presence of fungi. The overall picture that we get from our study is that antifungal volatiles produced by Collimonas could play an important role in realizing its mycophagous lifestyle. The current work is also interesting for understanding the ecological relevance of volatile production by soil bacteria in general as we found strong influences of root exudates composition and incubation conditions on the spectrum of volatiles produced.
Volatile-mediated interactions between phylogenetically different soil bacteria
Garbeva, P. ; Hordijk, C. ; Gerards, S. ; Boer, W. de - \ 2014
Frontiers in Microbiology 5 (2014). - ISSN 1664-302X
organic-compounds - pseudomonas-fluorescens - rhizosphere - microorganisms - communication - metabolites - regulators - collimonas - signals - systems
There is increasing evidence that organic volatiles play an important role in interactions between micro-organisms in the porous soil matrix. Here we report that volatile compounds emitted by different soil bacteria can affect the growth, antibiotic production and gene expression of the soil bacterium Pseudomonas fluorescens Pf0-1. We applied a novel cultivation approach that mimics the natural nutritional heterogeneity in soil in which P fluorescens grown on nutrient-limited agar was exposed to volatiles produced by 4 phylogenetically different bacterial isolates (Collimonas pratensis, Serratia plymuthica, Paenibacillus sp., and Pedobacter sp.) growing in sand containing artificial root exudates. Contrary to our expectation, the produced volatiles stimulated rather than inhibited the growth of P fluorescens. A genome-wide, microarray-based analysis revealed that volatiles of all four bacterial strains affected gene expression of P fluorescens, but with a different pattern of gene expression for each strain. Based on the annotation of the differently expressed genes, bacterial volatiles appear to induce a chemotactic motility response in P fluorescens, but also an oxidative stress response. A more detailed study revealed that volatiles produced by C. pratensis triggered, antimicrobial secondary metabolite production in P fluorescens. Our results indicate that bacterial volatiles can have an important role in communication, trophic - and antagonistic interactions within the soil bacterial community.
Explaining PAH desorption from sediments using Rock Eval analysis
Poot, A. ; Jonker, M.T.O. ; Gillissen, F. ; Koelmans, A.A. - \ 2014
Environmental Pollution 193 (2014). - ISSN 0269-7491 - p. 247 - 253.
polycyclic aromatic-hydrocarbons - historically contaminated sediments - supercritical-fluid extraction - solid-phase microextraction - laboratory-spiked sediments - soot-like materials - black carbon - polychlorinated-biphenyls - organic-compounds - hydrophobic p
Here, we provide Rock Eval and black carbon (BC) characteristics and polycyclic aromatic hydrocarbon (PAH) distribution coefficients (KD) for sediments from the Danube, Elbe, Ebro, and Meuse river basins. PAH desorption kinetic parameters were determined using sequential Tenax extractions. We show that residual carbon (RC) from Rock Eval analysis is an adequate predictor of fast, slow, and very slow desorbing fractions of 4-ring PAHs. RC correlated better than BC, the latter constituting only 7% of RC. A dual domain sorption model was statistically superior to a single domain model in explaining KD for low molecular weight PAHs, whereas the opposite was observed for high molecular weight PAHs. Because particularly the 4-ring PAHs are bioavailable and relevant from a risk assessment perspective and because their fast desorbing fractions correlate best with RC, we recommend RC as a relevant characteristic for river sediments.
Partitioning of perfluorooctanesulfonate and perfluorohexanesulfonate in the aquatic environment after an accidental release of aqueous film forming foam at Schiphol Amsterdam Airport
Kwadijk, C.J.A.F. ; Kotterman, M.J.J. ; Koelmans, A.A. - \ 2014
Environmental Toxicology and Chemistry 33 (2014)8. - ISSN 0730-7268 - p. 1761 - 1765.
perfluorinated surfactants - perfluoroalkyl acids - firefighting foam - organic-compounds - water - sulfonate - sediment - sorption - biota - fate
In the summer of 2008, an accidental release of Aqueous Film Forming Foam (AFFF) took place at Schiphol Amsterdam Airport (The Netherlands). After the release, water, fish and sediment samples were collected and analyzed for perfluoroalkyl sulfonates (PFSA). In situ perfluorooctane sulfonate (PFOS) KD values, BAF and BSAF values showed a remarkable agreement among reference and impacted sites, 10 weeks after the incident as well as after 3 years.
A possible simplification of the Goss-modified Abraham solvation equation
Noort, P.C.M. van - \ 2013
Chemosphere 93 (2013)9. - ISSN 0045-6535 - p. 1742 - 1746.
partition-coefficients - organic-compounds - gas-phase - water - thermodynamics - temperature - equilibrium - descriptors - solutes - model
Abraham solvation equations find widespread use in environmental chemistry and pharmaco-chemistry. Recently Goss proposed a modified Abraham solvation equation. For various partitioning processes, the present study investigates the consequences for the fit when the Abraham solvation parameter V is left out of this modified solvation equation. For air-organic solvent partition, the Abraham solvation parameter V can be omitted from the Goss-modified Abraham solvation equation without any loss of statistical quality. For air–water partitioning, organic biphasic system partitioning, as well as water-organic solvent partitioning, omitting the V parameter from the Goss-modified Abraham solvation equation leads to only a small deterioration of statistic quality.
Organophosphorus flame-retardant and plasticizer analysis, including recommendations form the first worldwide interlaboratory study
Brandsma, S.H. ; Boer, J. de; Leonards, P.E.G. ; Cofino, W.P. ; Covaci, A. - \ 2013
TrAC : Trends in Analytical Chemistry 43 (2013). - ISSN 0165-9936 - p. 217 - 228.
tandem mass-spectrometry - indoor environments - gas-chromatography - population characteristics - chemical-ionization - organic-compounds - phthalate-esters - water samples - new-model - air
The first worldwide interlaboratory study on organophosphorus flame retardants (PFRs) was organized to improve the quality of the data reported in the literature. The study involved standard solutions, dust, fish oil and sediment samples. The differences in coefficients of variation (CV) between the samples were related more to PFR concentration (with high blanks being reported by some laboratories) and less to matrix type. Not all participating laboratories suffered from blank problems, which indicated that it was possible to control the blanks. We include recommendations on how to improve analytical performance, especially to reduce contamination of blanks.
Incorporating availability/bioavailability in risk assessment and decision making of polluted sites, using Germany as an example
Kördel, W. ; Bernardt, C. ; Derz, K. ; Hund-Rinke, K. ; Harmsen, J. ; Peijenburg, W. ; Comans, R.N.J. ; Terytze, K. - \ 2013
Journal of Hazardous Materials 261 (2013). - ISSN 0304-3894 - p. 854 - 862.
polycyclic aromatic-hydrocarbons - solid-phase microextraction - polychlorinated-biphenyls - terrestrial environments - contaminated sediments - tenax(r) extraction - organic-compounds - soil extraction - heavy-metals - trace-metals
Nearly all publications dealing with availability or bioavailability of soil pollutants start with the following statement: the determination of total pollutant content will lead to an over-estimation of risk. However, an assessment of contaminated sites should be based on the determination of mobile fractions of pollutants, and the fractions with potential for mobilisation that threaten groundwater and surface water, and the actual and potential fractions available for uptake by plants, soil microflora and soil organisms. After reviewing the literature for method proposals concerning the determination of available/bioavailable fractions of contaminants with respect to leaching, plants, microorganisms (biodegradation) and soil organisms, we propose a testing and assessment scheme for contaminated sites. The proposal includes (i) already accepted and used methods, (ii) methods which are under standardisation, and (iii) methods for which development has just started in order to promote urgently needed research. (C) 2013 Elsevier B.V. All rights reserved.
A comparative survey of chemistry-driven in silico methods to identify hazardous substances under REACH
Nendza, M. ; Gabbert, S.G.M. ; Kühne, R. ; Lombardo, A. ; Roncaglioni, A. ; Benfenati, E. ; Benigi, R. ; Bossa, C. ; Strempel, S. ; Scheringer, M. ; Fernandez, A. ; Rallo, R. ; Giralt, F. ; Dimitrov, S. ; Mekenyan, O. ; Bringezu, F. ; Schüürmann, G. - \ 2013
Regulatory Toxicology and Pharmacology 66 (2013)3. - ISSN 0273-2300 - p. 301 - 314.
integrated testing strategies - minnow pimephales-promelas - organic-compounds - structural alerts - skin sensitization - aquatic toxicity - excess toxicity - estrogen-receptor - risk-assessment - fathead minnow
This paper presents an inventory of in silico screening tools to identify substance properties of concern under the European chemicals’ legislation REACH. The objective is to support the selection and implementation of appropriate tools as building blocks within integrated testing strategies (ITS). The relevant concerns addressed are persistence, bioaccumulation potential, acute and long-term aquatic toxicity, PBT/vPvB properties ((very) persistent, (very) bioaccumulative, toxic), CMR (carcinogenicity, mutagenicity, reproductive toxicity), endocrine disruption and skin sensitisation. The inventory offers a comparative evaluation of methods with respect to the underlying algorithms (how does the method work?) and the applicability domains (when does the method work?) as well as their limitations (when does the method not work?). The inventory explicitly addresses the reliability of predictions of different in silico models for diverse chemicals by applicability domain considerations. The confidence in predictions can be greatly improved by consensus modelling that allows for taking conflicting results into account. The inventory is complemented by a brief discussion of socio-economic tools for assessing the potential efficiency gains of using in silico methods compared to traditional in vivo testing of chemical hazards
Estimation of abraham solvation equation coefficients for hydrogen bond formation from abraham solvation parameters for solute activity and basicity
Noort, P.C.M. van - \ 2013
Chemosphere 90 (2013)2. - ISSN 0045-6535 - p. 344 - 348.
free-energy relationship - 298 k - partition-coefficients - organic-compounds - ionic liquids - lfer analysis - solubility - vapors - gases - water
Abraham solvation equations find widespread use in environmental chemistry and pharmaco-chemistry. The coefficients in these equations, which are solvent (system) descriptors, are usually determined by fitting experimental data. To simplify the determination of these coefficients in Abraham solvation equations, this study derives equations, based on Abraham solvation parameters for hydrogen acidity and basicity of the solvents involved, to estimate the value of the coefficients for hydrogen bond formation. These equations were applied to calculate Abraham solvation parameters for hydrogen acidity and basicity for polyoxymethylene, polyacrylate, sodium dodecylsulfate, some ionic liquids, alkanoyl phosphatidyl cholines, and lipids for which fitted values for Abraham coefficients for hydrogen bond formation were available
Extraction of sediment-associated polycyclic aromatic hydrocarbons with granular activated carbon
Rakowska, M.I. ; Kupryianchyk, D. ; Grotenhuis, J.T.C. ; Rijnaarts, H.H.M. ; Koelmans, A.A. - \ 2013
Environmental Toxicology and Chemistry 32 (2013)1. - ISSN 0730-7268 - p. 304 - 311.
environmental black carbon - soot-like materials - san-francisco bay - polychlorinated-biphenyls - surface-chemistry - pcb bioavailability - organic-compounds - marine sediment - sorption - adsorption
Addition of activated carbon (AC) to sediments has been proposed as a method to reduce ecotoxicological risks of sediment-bound contaminants. The present study explores the effectiveness of granular AC (GAC) in extracting polycyclic aromatic hydrocarbon (PAH) from highly contaminated sediments. Four candidate GAC materials were screened in terms of PAH extraction efficiency using single-step 24-h GAC extractions, with traditional 24-h Tenax extraction as a reference. Subsequently, sorption of native PAHs to the best performing GAC 1240W (0.45–1.70¿mm) was studied for sediment only and for GAC–sediment mixtures at different GAC–sediment weight ratios, using 76-µm polyoxymethylene (POM) passive samplers. Granular AC sorption parameters for PAHs were determined by subtracting the contribution of PAH sorption to sediment from PAH sorption to the GAC–sediment mixture. It appears that the binding of PAHs and the effectiveness of GAC to reduce sediment porewater concentrations were highly dependent on the GAC–sediment mixing ratio and hydrophobicity of the PAH. Despite the considerable fouling of GAC by organic matter and oil, 50 to 90% of the most available PAH was extracted by the GAC during a 28-d contact time, at a dose as low as 4%, which also is a feasible dose in field-scale applications aimed at cleaning the sediment by GAC addition and removal.
Identification of candidate volatiles that affect the behavioural response of the malaria mosquito Anopheles gambiae sensu stricto to an active kairomone blend: laboratory and semi-field assays
Smallegange, R.C. ; Bukovinszkine Kiss, G. ; Otieno, B. ; Mbadi, P.A. ; Takken, W. ; Mukabana, W.R. ; Loon, J.J.A. van - \ 2012
Physiological Entomology 37 (2012)1. - ISSN 0307-6962 - p. 60 - 71.
human skin emanations - integrated pest-management - mm-x traps - carbon-dioxide - vector control - aedes-aegypti - organic-compounds - chemical-composition - flight maneuvers - culex mosquitos
Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) is the most important vector of human malaria in sub-Saharan Africa, affecting the lives of millions of people. Existing tools such as insecticide-treated nets and indoor-residual sprays are not only effective, but also have limitations as a result of the development of resistance to insecticides and behavioural adaptations in biting time. Therefore, novel mosquito-control tools are needed. Odour-releasing traps have a potential for both trapping and surveillance purposes. Based on the outcome of ex vivo gene expression assays and in vivo electrophysiological assays on hundreds of volatile organic compounds, 29 ‘candidate behaviourally-disruptive organic compounds' (cBDOCs) are selected, belonging to 10 chemical categories, to be assayed in the laboratory using dual-choice olfactometers for the ability to modify the ‘attractiveness’ (i.e. significantly more insects being caught in the associated trap) of a basic volatile blend consisting of ammonia, lactic acid and tetradecanoic acid but without additional carbon dioxide. Compounds that either reduce or increase trap catches by the basic blend in the olfactometer experiments are tested under African conditions in choice experiments in a semi-field facility in Kenya. The release rates of cBDOCs are determined gravimetrically to allow the calculation of aerial concentrations at the trap outlet. Aerial concentrations in the sub-p.p.m. range are reported for the first time to influence mosquito behaviour. The results of the olfactometer and semi-field assays generally correspond. Under semi-field conditions, three compounds, 3-heptanol (0.025 p.p.m.), 2-methylpropanal (0.05 p.p.m.) and 4,5-dimethylthiazole (0.73 p.p.m.), significantly increase trap catches relative to the basic blend consisting of ammonia, lactic acid, tetradecanoic acid and carbon dioxide. 2-Acetylthiophene, 2-nonanone and 2-phenylethanol decrease the number of mosquitoes caught at all concentrations tested under semi-field conditions. These compounds hold promise as attractants and spatial repellents to be applied in mosquito control programmes.
Rapid tomato volatile profiling by using proton-transfer reaction mass spectrometry (PTS-MS)
Farneti, B. ; Cristescu, S.M. ; Costa, G. ; Harren, F.J.M. ; Woltering, E.J. - \ 2012
Journal of Food Science 77 (2012)5. - ISSN 0022-1147 - p. C551 - C559.
electronic nose - lycopersicon-esculentum - quality attributes - organic-compounds - flavor compounds - aroma volatiles - kidney beans - shelf-life - cultivars - harvest
The availability of rapid and accurate methods to assess fruit flavor is of utmost importance to support quality control especially in the breeding phase. Breeders need more information and analytical tools to facilitate selection for complex multigenic traits such as flavor quality. In this study, it is shown that proton-transfer reaction mass spectrometry (PTR-MS) is a suitable method to monitor at high sensitivity the emission of volatiles determining the tomato aromatic profile such as hexanal, hexenals, methanol, ethanol, and acetaldehyde. The volatiles emitted by 14 tomato varieties (at red stage) were analyzed by 2 solvent-free headspace methods: solid-phase microextraction/gas chromatography MS and PTR-MS. Multivariate statistics (principal component analysis and cluster analysis) of the PTR-MS results allow an unambiguous separation between varieties, especially with a clear fingerprinting separation between the different tomato types: round truss, cocktail, and cherry tomatoes. PTR-MS was also successfully used to monitor the changes in volatile profiles during postharvest ripening and storage.
The composition of carcass volatile profiles in relation to storage time and climate conditions
Kasper, J. ; Mumm, R. ; Ruther, J. - \ 2012
Forensic Science International 223 (2012)1-3. - ISSN 0379-0738 - p. 64 - 71.
organic-compounds - human decomposition - human cadavers - human remains - bacteria - identification - chromatography - preferences - succession - headspace
After death organisms are decomposed by a variety of enzymes and microorganisms. The decay is typically accompanied by the emission of a plethora of volatile organic compounds responsible for the unpleasant odour of a carcass and thus, for the attraction of necrophagous insects. The composition of carcass-related odour profiles strongly depends on the composition of macro-nutrients like fat, carbohydrates, and particularly protein, as well as on the presence of oxygen which influences the community of microorganisms colonising the corpse. The impact of abiotic factors like temperature and humidity on carcass-related volatile emission is less well understood although these parameters are known to have a strong impact on the growth of microorganisms. In the present study we investigated the volatile succession released from dead mice stored for one, ten and 30 days under warm/hot (wh, 22 degrees C/80-90% RH) or cold/dry (cd, 12 degrees C/40-60% RH) climate conditions. We identified 51 typical carcass volatiles by coupled gas chromatography-mass spectrometry and analysed the volatile profiles by multivariate statistical methods to find compounds characterising the different stages. Dead mice stored under wh conditions released volatiles much faster, in higher amounts, and in a greater diversity than those stored under cd conditions. The relatively low amount of sulphur chemicals released under cd conditions were most striking. The results are discussed with respect to their possible applicability in forensic science and insect ecology studies. (C) 2012 Elsevier Ireland Ltd. All rights reserved.
Sensitivity analysis on parameters and processes affecting vapor intrusion risk
Picone, S. ; Valstar, J.R. ; Gaans, P. van; Grotenhuis, J.T.C. ; Rijnaarts, H.H.M. - \ 2012
Environmental Toxicology and Chemistry 31 (2012)5. - ISSN 0730-7268 - p. 1042 - 1052.
unsaturated porous-media - capillary-fringe - indoor-air - organic-compounds - gas-transport - vadose zone - soil - groundwater - biodegradation - buildings
A one-dimensional numerical model was developed and used to identify the key processes controlling vapor intrusion risks by means of a sensitivity analysis. The model simulates the fate of a dissolved volatile organic compound present below the ventilated crawl space of a house. In contrast to the vast majority of previous studies, this model accounts for vertical variation of soil water saturation and includes aerobic biodegradation. The attenuation factor (ratio between concentration in the crawl space and source concentration) and the characteristic time to approach maximum concentrations were calculated and compared for a variety of scenarios. These concepts allow an understanding of controlling mechanisms and aid in the identification of critical parameters to be collected for field situations. The relative distance of the source to the nearest gas-filled pores of the unsaturated zone is the most critical parameter because diffusive contaminant transport is significantly slower in water-filled pores than in gas-filled pores. Therefore, attenuation factors decrease and characteristic times increase with increasing relative distance of the contaminant dissolved source to the nearest gas diffusion front. Aerobic biodegradation may decrease the attenuation factor by up to three orders of magnitude. Moreover, the occurrence of water table oscillations is of importance. Dynamic processes leading to a retreating water table increase the attenuation factor by two orders of magnitude because of the enhanced gas phase diffusion
Fate and monitoring of hazardous substances in temporary rivers
Ademollo, N. ; Capri, S. ; Froebrich, J. ; Patrolecco, L. ; Polesello, S. ; Puddu, A. ; Rusconi, M. ; Valsecchi, S. - \ 2011
TrAC : Trends in Analytical Chemistry 30 (2011)8. - ISSN 0165-9936 - p. 1222 - 1232.
polycyclic aromatic-hydrocarbons - fluvial suspended sediment - organic-compounds - contaminated sediment - dredged sediments - heavy-metals - tenax(r) extraction - aquatic ecosystems - air emissions - soil
Under climate-change conditions, temporary rivers will be the dominant surface-water bodies of the Mediterranean region. In order to manage this kind of water body appropriately, it is necessary to understand the chemical and ecological processes that involve hazardous substances in these environments. The processes during the dry phase have an important influence on the mobility and the availability of hazardous substances. This critical review presents the state of knowledge on the fate and the monitoring of hazardous substances in temporary rivers and highlights future trends in research in this field
Removal of micropollutants from aerobically treated grey water via ozone and activated carbon
Hernandez Leal, L. ; Temmink, B.G. ; Zeeman, G. ; Buisman, C.J.N. - \ 2011
Water Research 45 (2011)9. - ISSN 0043-1354 - p. 2887 - 2896.
afvalwaterbehandeling - waterzuivering - verontreinigende stoffen - verwijdering - afvalwater - aërobe behandeling - ozon - actieve kool - processors - vergelijkend onderzoek - waste water treatment - water treatment - pollutants - removal - waste water - aerobic treatment - ozone - activated carbon - processors - comparative research - endocrine-disrupting chemicals - waste-water - uv filters - organic-compounds - bisphenol-a - in-vitro - pharmaceuticals - ozonation - products - vivo
Ozonation and adsorption onto activated carbon were tested for the removal micropollutants of personal care products from aerobically treated grey water. MilliQ water spiked with micropollutants (100–1600 µgL-1) was ozonated at a dosing rate of 1.22. In 45 min, this effectively removed (>99%): Four parabens, bisphenol-A, hexylcinnamic aldehyde, 4-methylbenzylidene-camphor (4MBC), benzophenone-3 (BP3), triclosan, galaxolide and ethylhexyl methoxycinnamate. After 60 min, the removal efficiency of benzalkonium chloride was 98%, tonalide and nonylphenol 95%, octocrylene 92% and 2-phenyl-5-benzimidazolesulfonic acid (PBSA) 84%. Ozonation of aerobically treated grey water at an applied ozone dose of 15 mgL-1, reduced the concentrations of octocrylene, nonylphenol, triclosan, galaxolide, tonalide and 4-methylbenzylidene-camphor to below limits of quantification, with removal efficiencies of at least 79%. Complete adsorption of all studied micropollutants onto powdered activated carbon (PAC) was observed in batch tests with milliQ water spiked with 100–1600 µgL-1 at a PAC dose of 1.25 gL-1 and a contact time of 5 min. Three granular activated carbon (GAC) column experiments were operated to treat aerobically treated grey water. The operation of a GAC column with aerobically treated grey water spiked with micropollutants in the range of 0.1–10 µgL-1 at a flow of 0.5 bed volumes (BV)h-1 showed micropollutant removal efficiencies higher than 72%. During the operation time of 1728 BV, no breakthrough of TOC or micropollutants was observed. Removal of micropollutants from aerobically treated grey water was tested in a GAC column at a flow of 2 BVh-1. Bisphenol-A, triclosan, tonalide, BP3, galaxolide, nonylphenol and PBSA were effectively removed even after a stable TOC breakthrough of 65% had been reached. After spiking the aerobically treated effluent with micropollutants to concentrations of 10–100 µgL-1, efficient removal to below limits of quantification continued for at least 1440 BV. Both ozonation and adsorption are suitable techniques for the removal of micropollutants from aerobically treated grey water.
Solid phase extraction in combination with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry for the detailed investigation of volatiles in South African red wines
Weldegergis, B.T. ; Crouch, A.M. ; Górecki, T. ; Villiers, A. de - \ 2011
Analytica Chimica Acta 701 (2011)1. - ISSN 0003-2670 - p. 98 - 111.
bar sorptive extraction - organic-compounds - oak - components - aroma - aldehydes - modulator - pinotage - barrels - indexes
Comprehensive two-dimensional gas chromatography in combination with time-of-flight mass spectrometry (GC × GC–TOFMS) has been applied for the analysis of volatile compounds in three young South African red wines. In spite of the significant benefits offered by GC × GC–TOFMS for the separation and identification of volatiles in such a complex matrix, previous results utilizing headspace solid phase micro extraction (HS-SPME) demonstrated certain limitations. These were primarily associated with the choice of sample preparation technique, which failed to extract some influential semi-volatile wine constituents. Therefore, in the current report, we utilized solid phase extraction (SPE) in combination with GC × GC–TOFMS for the detailed investigation of particularly low-level semi-volatiles in South African wine. 214 compounds previously reported in grapes and related beverages were tentatively identified based on mass spectral data and retention indices, while 62 additional compounds were positively identified using authentic standards. The method proved particularly beneficial for the analysis of terpenes, lactones and volatile phenols, and allowed us to report the presence of numerous volatile compounds for the first time in Pinotage wines.
A simple McGowan specific volume correction for branching in hydrocarbons and its consequences for some other solvation parameter values
Noort, P.C.M. van; Haftka, J.J.H. ; Parsons, J.R. - \ 2011
Chemosphere 84 (2011). - ISSN 0045-6535 - p. 1102 - 1107.
energy relationship lser - organic-compounds - acyclic alkanes - phase - water - chromatography - descriptors
Differences in molecular properties between linear and branched alkanes as well as between compounds with branched alkyl groups is of relevance due to the large number of branched isomers of environmentally relevant compounds (e.g. fuels, fuel additives, surfactants). For branched alkane vapor pressures, the McGowan specific volume is a poor predictor. Therefore, in this study a correction on the McGowan specific volume is derived in terms of the number of branches and the number of pairs of vicinal branches to improve the prediction of branched alkane vapor pressures. This branching correction also brought branched /alkane solvent accessible volumes, octanol/water partition coefficients, air/hexadecane partition coefficients, and aqueous solubilities as well as alkyl-branched substituted aliphatic hydrocarbon air/hexadecane partition coefficients more in line with corresponding linear hydrocarbon properties when compared on a McGowan specific volume basis. Even for air–hexadecane partition coefficients of substituted aliphatic hydrocarbons with substituents at non-terminal carbons, application of the branching correction to the carbon bearing the substituent caused these partition coefficients to be more in line with those for linear compounds. Values for the Abraham A and B solvation parameters for nonlinear aliphatic ethers, amines, and alcohols, recalculated using branching corrected McGowan specific volumes, turned out to be closer to chemical expectations based on linear aliphatic ether, amine and alcohol values compared to previously reported experimental values obtained using uncorrected McGowan specific volumes. A comparison of alkylbenzene and alkene partition coefficient estimates from two different linear solvation energy relations, one containing a McGowan specific volume term and one without such a term, suggests that no branching correction is needed for alkyl groups at sp2 carbons. The main advantage of using branching corrected McGowan specific volumes is that the values of other solvation parameters become chemically more consistent.
Perfluorooctane sulphonate (PFOS) throughout the food production chain
Asselt, E.D. van; Rietra, R.P.J.J. ; Romkens, P.F.A.M. ; Fels-Klerx, H.J. van der - \ 2011
Food Chemistry 128 (2011)1. - ISSN 0308-8146 - p. 1 - 6.
contaminated drinking-water - perfluorinated compounds - human exposure - perfluoroalkyl contaminants - organic-compounds - treatment plants - surface-water - japan - fish - chemicals
Perfluorooctane sulphonate (PFOS) is a persistent organic pollutant with adverse effects on human health. Since dietary intake plays an important role in human exposure, the transfer of PFOS throughout the food chain needs further investigation. The aim of this paper is to give an overview of PFOS concentrations and transfer for the various chain steps from farm-to-fork. This reveals that most research focused on levels of PFOS in surface water and fish but data on soil and crops are largely missing. Furthermore, the uptake of PFOS by farm animals and subsequent transfer into meat and animal products needs further attention, as these products will eventually be consumed by the human population. Once the necessary data gaps are filled, the contribution of the various chain steps on the total PFOS intake can be established. Moreover, the effect of pollution events on the food chain can be established enabling appropriate actions in order to protect consumer health.
Diffusion Coefficients of Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons in Polydimethylsiloxane and Low-Density Polylethylene Polymers
Rusina, T. ; Smedes, F. ; Klanova, J. - \ 2010
Journal of Applied Polymer Science 116 (2010)3. - ISSN 0021-8995 - p. 1803 - 1810.
polyethylene ldpe films - organic-compounds - systems - selection - samplers - size
Diffusion coefficients (D) of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were determined by film-stacking technique in low-density polyethylene (LDPE) and two types of polydimethylsiloxane (PDMS) (also known as silicone rubber, SR) with the trade names AlteSil (TM) and Silastic. The estimated values of D for PCBs and PAHs over a wide range of hydrophobicity were 2-2.5 orders of magnitude lower in LDPE than in SR polymers. Log D (m(2) s(-1)) of PCBs ranged from -10.1 to -10.9 for SRs and from -12.4 to -13.7 for LDPE. For PAHs these ranges were -9.8 to -11.4 for SRs and -11.9 to -13.7 for LDPE. Compared with the D values calculated in water, D were 1-2 and 3-4 orders of magnitude lower in SR and LDPE, respectively. For PAH molecules, D was lower than for PCBs with a similar molecular weight, probably because of their more rigid structure. The range of log D for PCBs in SR was only 0.5 log units (factor of 3.2) versus 1.2 log units (factor of 16) in LDPE. Although compound classes showed different relations, a linear relation of D with total surface area was the most universal. This relation may be used for prediction of D values in SR and LDPE polymers for other organic compounds. (C) 201.0 Wiley Periodicals, Inc. J Appl Polym Sci 116: 1803-1810, 2010