| 1. |
- Eriksson, M., et al.
(författare)
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Determination of hydrocarbons in old creosote contaminated soil using headspace solid phase microextraction and GC-MS
- 2001
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Ingår i: Chemosphere. - 0045-6535 .- 1879-1298. ; 44:7, s. 1641-1648
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Tidskriftsartikel (refereegranskat)abstract
- Headspace solid phase microextraction (HS-SPME) has been used together with GC-MS to analyze organic substances directly in a soil, heavily contaminated with PAHs/creosote (similar to 300 mg/kg soil), from an old gaswork site in Stockholm, Sweden. The HS-SPME results, both qualitative and quantitative, were compared with traditional liquid extraction using ethyl acetate/hexane (20:80). It was shown that the concentrations determined with HS-SPME at 60 degreesC correlated well, for compounds containing up to two and three aromatic rings (naphthalenes, acenaphthene, acenaphthylene and fluorenes, while a lower concentration was obtained for phenanthrene, anthracene, fluoranthene and pyrene. The total concentrations for each compound determined with HS-SPME ranged from 2 to 25 mug/g soil. Quantification was done using standard addition of compounds directly to the soil samples. The bioavailable fraction of the compounds in the contaminated soil at 20 degreesC was analyzed using external calibration by spiking sterile uncontaminated sand (same texture and particle size as the contaminated soil but without a heavily sorbed organic fraction) with hydrocarbon standards in different concentrations. Storage of exposed fibers at 20 degreesC showed that analysis should be done within two days to make qualitative measurements and earlier (as soon as possible) for quantitative determinations.
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| 2. |
- Faldt, Anna, et al.
(författare)
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Childhood Overweight and Obesity During and After the COVID-19 Pandemic
- 2024
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Ingår i: JAMA PEDIATRICS. - 2168-6203 .- 2168-6211. ; 178:5, s. 498-500
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Tidskriftsartikel (refereegranskat)abstract
- This cohort study analyzes the prevalence of overweight and obesity among preschool children in Sweden before, during, and after the COVID-19 pandemic and longitudinal trends in body mass index.
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| 3. |
- Faldt, J., et al.
(författare)
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Comparison of headspace techniques for sampling volatile natural products in a dynamic system
- 2000
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Ingår i: Zeitschrift für Naturforschung C - A Journal of Biosciences. - : Walter de Gruyter GmbH. - 0939-5075 .- 1865-7125. ; 55:04-mar, s. 180-188
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Tidskriftsartikel (refereegranskat)abstract
- Commonly used dynamic sorption techniques for collecting biologically active volatile compounds have been compared. Solid phase microextraction (SPME) using two types of fibers (polydimethylsiloxane, PDMS, 100 mu m, and carbowax/divinylbenzene, CW/DVB, 65 mu m) was compared to purge and trap methods (Porapak Q, Tenax TA and charcoal) and a technique based on absorption in methanol in a cooling bath. Sampling was done in a stream of purified air (20 ml/min) in a closed and temperature-regulated (27 degrees C) glass tube, passing over a capillary tube containing a hexane solution of tridecane, heptadecane, 1-octen-3-ol, 1-hexadecanol, ethyl tetradecanoate, alpha-pinene, linalool, terpinen-4-ol, cis-verbenol, verbenone, beta-caryophyllene, E,E-farnesol, and geranylgeraniol. With all of the methods, the sampling was performed for a period of 30 min before extraction and analysis was done on a GC-FID system. In general, SPME gave a higher response for all compounds except for alpha-pinene, which was only extracted by the CW/DVB fiber. Purge and trap methods and methanol absorption gave the same response for all substances extracted. None of the methods extracted hexadecanol and geranylgeraniol under the conditions used. However, the SPME equipped with the PDMS coating extracted heptadecane, E,E-farnesol and ethyl tetradecanoate. Our results show that SPME, when selecting the fibers to fit the polarity and volatility of the compounds, is an outstanding extraction method compared to purge and trap and methanol absorption, especially for a qualitative analysis. The best conditions for storing fibers exposed to compounds of high volatility were at low temperatures (6 degrees C) in sealed vials, while the worst way was to leave the exposed fiber unprotected at room temperature (22 degrees C). The dynamic sampling system was effectively tested on a fruiting body of a polypore fungus (Ganoderma applanatum) emitting 1-octen-3-ol, and again SPME showed to be the most sensitive technique.
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| 4. |
- Faldt, J., et al.
(författare)
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Correlations between selected monoterpene hydrocarbons in the xylem of six Pinus (pinaceae) species
- 2001
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Ingår i: Chemoecology. - 0937-7409 .- 1423-0445. ; 11:2, s. 97-106
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Tidskriftsartikel (refereegranskat)abstract
- The compositions of 23 monoterpene hydrocarbons of six pine species (Pinus sylvestris, P. yunnanensis ll,ris, P. armandii, P. tropicalis, P. cubensis and P. caribaca) were compared, using multivariate data analysis. Four of the six species were clearly different from the other species in a Principal Components Analysis (PCA) model, based on the relative amounts (selective normalization) of the monoterpenes. The correlation coefficients between constituents were determined separately for each species and the strongest correlations were found between (+)-alpha -pinene and (+)-camphene and between the corresponding (-)-enantiomers, in all species. This pattern, i.e. a good correlation in all species, was neither shown by the correlation of the structurally more similar (+)-alpha/beta -pinenes, nor by the (-)-alpha/beta -pinenes or within the enantiomeric pairs of alpha -pinene and beta -pinene. For these pairs of monoterpenes, good correlations were found in some species. None of the species showed good correlations in all the investigated monoterpene pairs presented here. Correlations between monoterpenes in insect-attacked trees (P. cubensis and P. caribaea, attacked by Dioryctria horneana, and P. yunnanensis, attacked by Tomicus piniperda) were also determined. The results are discussed from chemotaxonomic and biosynthetic points of view.
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| 5. |
- Faldt, Jenny, et al.
(författare)
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Influence of fungal infection and wounding on contents and enantiomeric compositions of monoterpenes in phloem of Pinus sylvestris
- 2006
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 32:8, s. 1779-1795
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Tidskriftsartikel (refereegranskat)abstract
- To identify chemical resistant markers induced by fungal or mechanical injury, young trees of Scots pine (Pinus sylvestris) were subjected to inoculations of blue stain fungi associated with the pine shoot beetles Tomicus piniperda and T. minor. Among the 20 trees selected for chemical analyses, 16 were divided into four groups: one as control and three were pretreated by wounding only, or by inoculation with either the blue stain fungus Leptographium wingfieldii or Ophiostoma canum. Four wk after pretreatment, all 16 pretreated trees were mass-inoculated with L. wingfieldii. The absolute and relative amounts, as well as the enantiomeric compositions of monoterpene hydrocarbons in the phloem, were determined via a small sample of the phloem before and after the pretreatment and mass inoculation, by using two-dimensional gas chromatography (2D GC) and GC-mass spectrometry (MS). After mass inoculation, the absolute amounts of most of the monoterpenes decreased in the phloem sampled > 20 cm from the fungal infection, and were higher in the phloem sampled within the infected reaction zone. The relative amounts of both (-)-beta-pinene and (-)-limonene increased in phloem samples taken > 20 cm above the fungal inoculation in the preinoculated trees compared with phloem sampled from the remaining four control trees. The enantiomeric compositions of beta-pinene and limonene changed, after fungal growth, at defined distances from the inoculation site: the proportion of the (-)-enantiomers was highest in the phloem sampled > 20 cm from the fungal inoculation. Four wk after pretreatment, monoterpene production in the phloem at the site of inoculation was more enhanced by L. wingfieldii than by O. canum. However, the different virulence levels of the fungi did not affect the enantiomeric composition of the monoterpenes. The biosynthesis of monoterpene enantiomers is discussed in relation to induced pathogen resistance.
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| 6. |
- Rostelien, T., et al.
(författare)
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The plant sesquiterpene germacrene D specifically activates a major type of antennal receptor neuron of the tobacco budworm moth Heliothis virescens
- 2000
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 25:2, s. 141-148
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Tidskriftsartikel (refereegranskat)abstract
- Plants release hundreds of volatiles that are important in interactions with insects or other organisms. However, knowledge is scarce as to which of the compounds are detected by the organism's olfactory receptor neurons. In the present study, single receptor neurons on the antennae of the tobacco budworm moth, Heliothis virescens, were screened far their sensitivities to naturally produced plant volatiles by the use of gas chromatography linked to electrophysiological recordings from single cells (GC-SCR). Plant volatiles, collected by aeration of host and non-host plants, were tested on each receptor neuron via parallel GC-columns. Thus, simultaneous recordings of the gas chromatogram and the neuron responses to each component were obtained. One type of receptor neuron, appearing in 80% of all experiments, responded with high sensitivity and selectivity to one particular component, present in host as well as non-host mixtures. The component, identified as a sesquiterpene hydrocarbon by linked gas chromatography-mass spectrometry, was isolated from a sesquiterpene fraction of cubebe oil and identified by NMR as germacrene D. The purified compound was then re-tested via gas chromatography on the same receptor neuron type, verifying the identification. A weaker response to another sesquiterpene hydrocarbon was also recorded.
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| 7. |
- Sjödin, Kristina, et al.
(författare)
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Occurrence and correlations of monoterpene hydrocarbon enantiomers in Pinus sylvestris and Picea abies
- 2000
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Ingår i: Journal of Chemical Ecology. - 0098-0331 .- 1573-1561. ; 26:7, s. 1701-1720
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Tidskriftsartikel (refereegranskat)abstract
- The relative amounts and enantiomeric compositions of monoterpene hydrocarbons in branch and trunk xylem, in needles, and in resin from apical buds in 18 Pinus sylvestris trees have been determined and compared with the terpene content in branch xylem and needles of Picea abies. Besides the high amount of (+)-3-carene, an excess of (+)-alpha-pinene has been found in P. sylvestris, whereas in P. abies (-)-alpha-pinene dominates over (+)-alpha-pinene. In P. sylvestris, clear positive correlations were found between (+)-alpha-pinene and (+)-camphene in the four tissues analyzed. Good positive correlations were also observed between (-)-alpha-pinene and (-)-camphene in the two types of xylem, between (+)-alpha-pinene and (+)-beta-pinene in the resin, and between tricyclene and (-)-camphene in resin and needles. In P. abies, positive correlations were found between (+)-alpha-pinene and (+)-camphene in the branch xylem and between tricyclene and (-)-camphene as well as between (-)-alpha-pinene and (-)-camphene in the needles. Complex relationships between (-)-alpha-pinene and (-)-beta-pinene were found both in the P. abies and in the P. sylvestris tissues. The importance of the enantiomeric composition of alpha-pinene for the host selection of Ips typographus, Tomicus piniperda, and Hylobius abietis is discussed.
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