| 1. |
- Harner, T., et al.
(författare)
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Enantiomer Fractions Are Preferred to Enantiomer Ratios for Describing Chiral Signatures in Environmental Analysis
- 2000
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 34:1, s. 218-220
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Tidskriftsartikel (refereegranskat)abstract
- The enantiomer ratio (ER) is currently the standard descriptor of enantiomeric (chiral) signatures for environmental samples. In this paper, we argue for the adoption of the enantiomer fraction (EF) as the standard descriptor by showing drawbacks to the use of ER. The enantiomer fraction is superior because it provides a more meaningful representation of graphical data and is more easily employed in mathematical fate expressions. Several useful expressions are presented that allow EF to be used for tracking and apportioning chemical movement between environmental compartments and for investigating microbial degradation processes.
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| 2. |
- Magnusson, R, et al.
(författare)
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Determination of chemical composition and mutagenicity in particles from chainsaw exhaust. Experimental set-up, stability and results from two different fuels
- 2000
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Ingår i: Environmental Technology. - 0959-3330. ; 21:7, s. 819-29
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Tidskriftsartikel (refereegranskat)abstract
- A dilution tunnel for sampling of particles and gaseous emissions in chainsaw exhaust was constructed and tested for reproducibility. In addition the equipment was used to measure chainsaw emissions when using two different fuels, aliphatic petrol with synthetic lubricating oil and regular lead-free petrol with mineral lubricating oil. The content of polycyclic aromatic hydrocarbons (PAH) and the mutagenicity of sampled particles were measured as well as the concentration of carbon monoxide (CO), nitrogen oxides (NOx) and aldehydes in the exhaust. particles were sampled isokinetically and collected on a filter followed by two polyurethane foam plugs (PUF) in series for sampling of the semivolatile components. PAH were analysed by a coupled liquid chromatography - gas chromatography (LC-GC) system and mutagenicity testing was carried out by using Ames Salmonella assay. The measured physical parameters as well as the particulate, semivolatile and gaseous emissions showed that reproducible measurements of exhaust emissions could be achieved using this experimental set-up. In terms of mutagenicity when testing for reproducibility, a small but significant effect was observed for the Salmonella strains TA98 and TA100 in the absence of a metabolizing system, both for the particulate phase and the semivolatile components. A significant difference was seen between the two different fuels tested, the conventional petrol with mineral oil having 5-10 times higher concentrations of different PAH compounds and a much higher mutagenic effect for all strains. This difference was seen both for the particulate phase and the semivolatile components.
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| 3. |
- Wiberg, Karin, et al.
(författare)
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The Enantioselective Bioaccumulation of Chiral Chlordane and -HCH Contaminants in the Polar Bear Food Chain
- 2000
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 34:13, s. 2668-74
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Tidskriftsartikel (refereegranskat)abstract
- The enantiomer ratios (ERs) of -HCH and chlordane related compounds (CHLs) were examined in the polar bear food chain (arctic cod-ringed seal-polar bear), using chiral gas chromatography-mass spectrometry (GC-MS). The cod showed near-racemic mixtures (ER = 1) for most of the compounds. In contrast, ERs in ringed seal and polar bear were frequently nonracemic (ER 1), due to enantiomer-specific biotransformation. As (+)--HCH was transferred up the food chain, it became more abundant relative to (-)--HCH. For the CHLs, there was no uniform trend for the ER changes and the increasing trophic level. Apparent chiral biomagnification factors (BFs) were calculated and up to a 20-fold difference in the BF between enantiomers was found. Analysis of chiral BFs relative to CB-153 indicated that oxychlordane was formed by ringed seal and metabolized by polar bears. However, the ERs did not change significantly as a result of these biotransformations. Multivariate statistical methods revealed the clustering of sample categories and were used to investigate the relationships between the ERs, chemical residue concentrations, and biological data. ERs were important variables for the sample groupings and for the class separation of male/female seals and fat/liver tissues. The variance in the cytochrome P450 CYP2B protein content of bear liver could be explained by the variances in chemical residue data. In this analysis the ERs were of secondary importance. The ERs of some highly recalcitrant CHLs in polar bear adipose showed linear relationships with the age of the bears.
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