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Enantiospecific Analysis and Environmental Behavior of Chiral Persistent Organic Pollutants (POPs)
Umeå University, Faculty of Science and Technology, Department of Chemistry.
2002 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Many persistent organic pollutants (POPs) are chiral. These pollutants are generally released into the environment as racemates, but frequently undergo alterations in enantiomeric composition as soon as they are subjected to life chemistry processes. Enantiospecific analysis of chiral POPs is important since enantiomers of chiral compounds often exhibit differences in biological activity, and most biochemical processes in nature are stereospecific. For abiotic processes, such as air-water gas exchange, deposition and long-range air transport, enantiomeric patterns of POPs may be used as chemical markers.

The aim of the work described in this thesis was to improve our knowledge about the presence and fate of enantiomers of chiral POPs inthe environment to provide a sound basis for accurate risk assessment. The compounds included were organochlorine (OC) pesticides (α-HCH, chlordanes and o,p’-DDT), atropisomeric PCBs and some of their respective metabolites (heptachlor-exo-epoxide, oxychlordane and MeSO2-PCBs).

Analytical methods for chiral PCBs were developed, and the elution sequences of (+) and (−)-enantiomers were determined. Enantiomeric fraction (EF) was proposed as a better reflector of chiral composition than the conventional enantiomeric ratio (ER).

Enantioselective bioprocessing in various compartments was studied, with the main emphasis on factors controlling chiral composition in biota Correlations were detected between changes in EFs and differences in trophic levels. The changes were, however, not consistent for all compounds. Instead, the enantiomeric composition was found to be species-specific in the polar bear food chain and in aquatic species from the Baltic Sea. The EFs of some POPs in Baltic seals were related tonutritional status and biotransformation capacity.

Enantiomeric and isomeric patterns were used to investigate abiotic processes in the southern Baltic Sea environment and EFs were used tostudy soil as a source of atmospheric heptachlor-exo-epoxide.

Place, publisher, year, edition, pages
2002. , 90 p.
Identifiers
URN: urn:nbn:se:umu:diva-9ISBN: 91-7305-162-4 (print)OAI: oai:DiVA.org:umu-9DiVA: diva2:144968
Public defence
(English)
Available from: 2002-01-25 Created: 2002-01-25 Last updated: 2012-06-28Bibliographically approved
List of papers
1. Determination of the gas chromatographic elution sequences of the (+)- and (-)-enantiomers of stable atropistomeric PCBs on Chirasil-Dex
Open this publication in new window or tab >>Determination of the gas chromatographic elution sequences of the (+)- and (-)-enantiomers of stable atropistomeric PCBs on Chirasil-Dex
1996 (English)In: HRC Journal of High Resolution Chromatography, ISSN 0935-6304, E-ISSN 1521-4168, Vol. 19, no 7, 373-376 p.Article in journal (Refereed) Published
Abstract [en]

Pure enantiomers of chiral (atropisomeric) polychlorinated biphenyls (PCBs) obtained by high-performance liquid chromatography were used to establish the gas chromatographic elution sequences of the (+)- and (−)-enantiomers of six PCB atropisomers on Chirasil-Dex. The elution order was found to be (−/+) for PCBs 84, 132, 136, and 176 and (+/−) for PCBs 135 and 174. The retention characteristics of all 19 tri- and tetra-ortho atropisomeric PCBs were also investigated. Nine of the atropisomers could be separated using this chiral selector. PCBs 95, 132, and 149 were completely resovled and PCBs 84, 91, 135, 136, 174, and 176 were partially separated (R = 0.7–0.9). All of the separated congeners are 2,3,6-substituted in at least one ring, and conversely – none of the congeners that lacks 2,3,6-substitution could be separated. Thus, chiral recognition and enantiomer separation seems to be strongly governed by 2,3,6-substitution.

Place, publisher, year, edition, pages
Weinheim: Wiley-VCH Verlagsgesellschaft, 1996
Keyword
enantioselective gas chromatography, stable atropisomeric polychlorinated biphenyls (PCBs), elution sequences, cyclodextrin derivatives, Chirasil-Dex
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-5443 (URN)10.1002/jhrc.1240190703 (DOI)A1996VE01000002 ()
External cooperation:
Available from: 2002-01-25 Created: 2002-01-25 Last updated: 2017-12-14Bibliographically approved
2. Enantioselective gas chromatography/mass spectrometry of methylsulfonyl PCBs with application to arctic marine mammals
Open this publication in new window or tab >>Enantioselective gas chromatography/mass spectrometry of methylsulfonyl PCBs with application to arctic marine mammals
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1998 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 70, no 18, 3845-3852 p.Article in journal (Refereed) Published
Abstract [en]

Four different commercially available cyclodextrin (CD) capillary gas chromatography (GC) columns were tested for the enantioselective separation of nine environmentally persistent atropisomeric 3- and 4-methylsulfonyl PCBs (MeSO2-CBs). The selected columns contained cyclodextrins with various cavity diameters (β- or γ-CD), which were methylated and/or tert-butyldimethylsilylated (TBDMS) in the 2,3,6-O-positions. The β-CD column with TBDMS substituents in all of the 2,3,6-O-positions was by far the most selective column for the MeSO2-CBs tested. Enantiomers of congeners with 3-MeSO2 substitution were more easily separated than those with 4-MeSO2 substitution. The separation also seemed to be enhanced for congeners with the chlorine atoms on the non-MeSO2-containing ring and clustered on one side of the same ring. The 2,3-di-O-methyl-6-O-TBDMS-β-CD was found to give somewhat better selectivity than the corresponding γ-CD, in comparison between the two columns, which were identical in all other respects. Enantioselective analysis of arctic ringed seal (Phoca hispida) and polar bear (Ursus maritimus) adipose tissue revealed a strong dominance of certain enantiomers. For example, the enantiomer ratio (ER) of 3-MeSO2-CB149 was 0.32 and <0.1 in ringed seal blubber and polar bear fat, respectively. These low ER values are indicative of highly enantioselective formation, enantioselective metabolism, enantioselective transport across cell membranes, or a combination of the three in both species. Comparable results for the enantiomeric analysis of MeSO2-CBs in biotic tissue extracts were obtained using two highly selective mass spectrometric techniques, ion trap mass spectrometry/mass spectrometry and electron capture negative ion low-resolution mass spectrometry.

Place, publisher, year, edition, pages
Washington: American Chemical Society (ACS), 1998
Keyword
polychlorinated biphenyls, modified cyclodextrins, separation, enantiomers, atropisomers, contaminants, metabolites, pollutants, samples, ratios
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-5444 (URN)10.1021/ac980064g (DOI)000075911500019 ()
External cooperation:
Available from: 2002-01-25 Created: 2002-01-25 Last updated: 2017-12-14Bibliographically approved
3. Enantiomer Fractions Are Preferred to Enantiomer Ratios for Describing Chiral Signatures in Environmental Analysis
Open this publication in new window or tab >>Enantiomer Fractions Are Preferred to Enantiomer Ratios for Describing Chiral Signatures in Environmental Analysis
2000 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 34, no 1, 218-220 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2000
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-5445 (URN)10.1021/es9906958 (DOI)
Available from: 2002-01-25 Created: 2002-01-25 Last updated: 2017-12-14Bibliographically approved
4. Chiral analysis of organochlorine pesticides in Alabama soils
Open this publication in new window or tab >>Chiral analysis of organochlorine pesticides in Alabama soils
2001 (English)In: Chemosphere, Vol. 45, no 6-7, 843-8 p.Article in journal (Refereed) Published
Abstract [en]

The enantiomeric composition of organochlorine (OC) pesticide residues was investigated in 32 agricultural and 3 cemetery soils from Alabama. The enantiomeric signatures were similar to those from other soils in US and Canada. The enantiomer fractions (EFs) of o,p′-DDT showed great variability, ranging from 0.41 to 0.57 while the EFs of chlordanes and chlordane metabolites were less variable and differed in general significantly from racemic. Enantioselective depletion of (+)trans-chlordane, (−)cis-chlordane, the first eluting enantiomer of MC5, and enrichment of (+)heptachlor-exo-epoxide and (+)oxychlordane was found in a large majority of the samples with detectable residues. The enantiomeric composition of α-hexachlorocyclohexane was racemic or close to racemic.

Keyword
Enantiomer fraction, o, p′-DDT, α-HCH, Chlordanes, Chlordane metabolites
Identifiers
urn:nbn:se:umu:diva-8891 (URN)doi:10.1016/S0045-6535(01)00033-9 (DOI)
Available from: 2008-02-19 Created: 2008-02-19 Last updated: 2012-06-28Bibliographically approved
5. Enantioselective analysis of organochlorine pesticides in herring and seal from the Swedish marine environment
Open this publication in new window or tab >>Enantioselective analysis of organochlorine pesticides in herring and seal from the Swedish marine environment
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1998 (English)In: Marine Pollution Bulletin, ISSN 0025-326X, E-ISSN 1879-3363, Vol. 36, no 5, 345-353 p.Article in journal (Refereed) Published
Abstract [en]

Factors influencing the changes of enantiomeric ratios (ERs) in herring (Clupea harengus), grey seal (Halichoerus grypus), harbour seal (Phoca vitulina) and ringed seal (Phoca hispida) collected along the Swedish coastline were studied by enantioselective high-resolution gas chromatography (HRGC). Three-year-old male and female herring individuals from different sampling sites were selected, whereas seal blubber and liver samples represented different species, sexes and geographical locations. Enantioselective analysis of α-hexachlorocyclohexane (α-HCH), chlordanes and chlordane metabolites were performed. In general, herring showed similar ERs within the Baltic Sea. Results indicate that species specific differences are important factors controlling the ERs of Baltic seals. Inverse ERs in seal blubber and liver, and a low deviation from the racemic ratio of some components in the liver, indicate that not only enantioselective degradation but also stereoselectivity of other processes are responsible for the changes of ERs in biota.

Place, publisher, year, edition, pages
Oxford: Pergamon Press, 1998
Keyword
pesticides, bioaccumulation, degradation, enantiomers, Baltic seals, herring
National Category
Environmental Sciences Ecology
Identifiers
urn:nbn:se:umu:diva-5447 (URN)10.1016/S0025-326X(97)00187-2 (DOI)000074689400012 ()
External cooperation:
Available from: 2002-01-25 Created: 2002-01-25 Last updated: 2017-12-14Bibliographically approved
6. The Enantioselective Bioaccumulation of Chiral Chlordane and -HCH Contaminants in the Polar Bear Food Chain
Open this publication in new window or tab >>The Enantioselective Bioaccumulation of Chiral Chlordane and -HCH Contaminants in the Polar Bear Food Chain
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2000 (English)In: Environmental Science & Technology, Vol. 34, no 13, 2668-74 p.Article in journal (Refereed) Published
Abstract [en]

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.

Identifiers
urn:nbn:se:umu:diva-8945 (URN)doi:10.1021/es990740b (DOI)
Available from: 2008-02-22 Created: 2008-02-22 Last updated: 2012-06-28Bibliographically approved
7. Concentrations and enantiomer fractions of organochlorine compounds in Baltic species hit by reproductive impairment
Open this publication in new window or tab >>Concentrations and enantiomer fractions of organochlorine compounds in Baltic species hit by reproductive impairment
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2002 (English)In: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 21, no 12, 2542-2551 p.Article in journal (Refereed) Published
Abstract [en]

Concentrations and enantiomer fractions (EFs) of organochlorine compounds (OCs) were determined in tissues of gray seal (Halichoerus grypus) and salmon (Salmo salar) originating from the Baltic Sea. The selected seal specimens ranged from starved to unstarved animals, and some of them suffered from a disease complex, while the salmon samples originated from individuals, which were known to produce offspring with and without the M74 syndrome. Significant differences in residue levels and EFs were found between seal groups but not between M74 salmon and non-M74 salmon. The relations between chemical and biological variables of seal samples were investigated with multivariate statistics. Poor health status correlated strongly with age, while bad nutrition condition was associated mainly with high pollution loads and distinctively nonracemic chiral OC compositions. High biotransformation rate (as indicated by fraction of chlordane metabolites in relation to total level of chlordanes) was also associated with large deviations from racemic values and high contaminant levels.

Keyword
Baltic;Salmon;Gray seal;Organochlorine compounds;Enantiomer fraction
National Category
Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-5449 (URN)10.1002/etc.5620211204 (DOI)
Available from: 2002-01-25 Created: 2002-01-25 Last updated: 2017-12-14Bibliographically approved
8. Soil as a source of atmospheric heptachlor epoxide
Open this publication in new window or tab >>Soil as a source of atmospheric heptachlor epoxide
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1998 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 32, no 10, 1546-1548 p.Article in journal (Refereed) Published
Abstract [en]

The chiral pesticide heptachlor can undergo photolysis to yield the racemic products heptachlor-exo-epoxide (HEPX) and photoheptachlor. Heptachlor is also metabolized to nonracemic HEPX in biological systems and soils. HEPX in ambient air samples from the southern United States and Lakes Ontario and Superior was nonracemic and enriched in the (+) enantiomer. Average enantiomer ratios (ER = areas of (+)/(-) HEPX) in these locations ranged from 1.51 to 2.02, and were similar to ER values of HEPX reported for agricultural soils. Airborne heptachlor was racemic, with ERs of 0.98-1.02. These results suggest that the main source of HEPX in ambient air is not photolysis of heptachlor, hut rather metabolism of heptachlor in soils followed by volatilization of HEPX. The study exemplifies the use of chiral analysis for investigating the environmental fate of pesticides.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-5450 (URN)10.1021/es971110h (DOI)000073648700028 ()
Available from: 2002-01-25 Created: 2002-01-25 Last updated: 2017-12-14Bibliographically approved
9. Chiral pesticides as tracers of air-surface exchange
Open this publication in new window or tab >>Chiral pesticides as tracers of air-surface exchange
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1998 (English)In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 102, no 1, 43-49 p.Article in journal (Refereed) Published
Abstract [en]

The enantiomers of chiral pesticides are selectively broken down in soil and water to yield residues and metabolites, which are non-racemic. The distinctive enantiomer signatures of residues are preserved upon volatilization, providing site-specific tracers for air-soil and air-water exchange. Applications of enantiomeric tracers include distinguishing the atmospheric transport of freshly applied pesticides from those which are 'recycled' from lakes, oceans and soil, and investigating biotic vs abiotic degradation pathways. Examples are given of using pesticide enantiomers to follow volatilization from the Great Lakes and arctic waters and as indicators of pesticide emissions from agricultural soils.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-5451 (URN)10.1016/S0269-7491(98)00062-1 (DOI)000076978500004 ()
Available from: 2002-01-25 Created: 2002-01-25 Last updated: 2017-12-14Bibliographically approved
10. Concentrations and fluxes of hexachlorocyclohexanes (HCHs) and chiral composition of α-HCH in environmental samples from the southern Baltic Sea.
Open this publication in new window or tab >>Concentrations and fluxes of hexachlorocyclohexanes (HCHs) and chiral composition of α-HCH in environmental samples from the southern Baltic Sea.
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Manuscript (Other academic)
Identifiers
urn:nbn:se:umu:diva-5452 (URN)
Available from: 2002-01-25 Created: 2002-01-25 Last updated: 2010-01-13Bibliographically approved

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