| 411. |
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| 412. |
- Rodushkin, Ilya, et al.
(författare)
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Sources of contamination and remedial strategies in the multi-elemental trace analysis laboratory
- 2010
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 396:1, s. 365-377
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In theory, state of the art inductively coupled plasma mass spectrometry (ICP-MS) instrumentation has the prerequisite sensitivity to carry out multi-elemental trace analyses at sub-ng L-1 to sub-pg L-1 levels in solution. In practice, constraints mainly imposed by various sources of contamination in the laboratory and the instrument itself, and the need to dilute sample solutions prior to analysis ultimately limit detection capabilities. Here we review these sources of contamination and, wherever possible, propose remedial strategies that we have found efficacious for ameliorating their impact on the results of multi-elemental trace analyses by ICP-MS. We conclude by providing a list of key points to consider when developing methods and preparing the laboratory to routinely meet the demands of multi-elemental analyses at trace analytical levels by ICP-MS.
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| 413. |
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| 414. |
- Sellström, Ulla, 1956-
(författare)
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Determination of some polybrominated flame retardants in biota, sediment and sewage sludge
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Brominated flame retardants (BFRs) are mainly used in different polymers, and can be released to the environment during industrial processes, during the entire life-time of the flame-retarded product and after disposal. The aim of the present study was to gain knowledge about occurrence and concentrations of some BFRs in the environment, to search for sources for these chemicals and to investigate changes in concentrations over time. The emphasis was on the polybrominated diphenyl ethers (PBDE), but hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) were also studied to some extent.The analytical method used was mass spectrometry run in the electron capture negative ionisation (ECNI) mode. The formation of bromide ions was utilised as a sensitive and selective detection method for the brominated compounds.BFRs seem to be ubiquitous contaminants in the environment. Long range transport in air may explain the contamination of PBDE in whitefish from the pristine mountain lake Storvindeln. The highest concentrations are found in samples collected in the vicinity of industrial (textile and polymer) activities, where they are/have been used. Samples from heavily populated areas contain higher concentrations of PBDE than samples from remote areas, which results in a south-north geographical trend in concentrations. Generally the concentrations are higher in aquatic organisms than in those from terrestrial environments. Municipal sewage sludge, which reflects the current use of chemicals in society, contains all the BFRs covered in this thesis.DecaBDE was only indicated in biota, but was found in high concentrations in sediment. Higher concentrations of tetra- and pentaBDE in piscivorous birds and mammals compared to the fish they eat indicate biomagnification of these substances. HBCD was found in both fish and sediment from the Rivers Viskan/Häggån, where it has been used to some extent as a substitute for decaBDE in the textile industry. HBCD was also detected in guillemot eggs from a background area in the Baltic Sea.Increasing concentrations over time of tetra- and pentaBDE was first indicated in a sediment core from the Baltic Sea, sampled in 1987. This increase was later confirmed in guillemot eggs from the island Stora Karlsö in the Baltic, but from the mid-late 1980s, the concentrations started to decrease in this species. This decrease is not in agreement with the results from other studies, indicating different sources of contamination.
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| 415. |
- Sjödin, Andreas, 1971-
(författare)
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Occupational and dietary exposure to organohalogen substances, with special emphasis on polybrominated diphenyl ethers
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is aimed at widening the current knowledge base about human exposure to brominated flame retardants (BFRs), particularly polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA). Data on exposures to some of the traditional organohalogen substances (OHS) have been included for comparative reasons. BFRs are produced and applied in large quantities for fire prevention purposes in our society today. The ongoing production and use may lead to a dramatic pollution problem in the future unless they are used with care. Human exposure to BFRs must also be understood, assessed and measures based on the scientific knowledge should be taken when necessary.Ambient air measurements of BFRs at an electronics dismantling plant showed significantly higher levels of hexa- to decabrominated diphenyl ethers (hexaBDE-decaBDE), tetrabromobisphenol A (TBBPA) and 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE) than in any other indoor facilities, including IT intensive work environments. Serum PBDE levels in workers at a dismantling plant were found to have significantly elevated concentrations of hepta- to decaBDEs, compared to a non-exposed group of women, comprised of cleaners. Results were obtained that unambiguously show that decaBDE is bioavailable, even though it has a molecular mass of 959 and previously was regarded as not being bioavailable. The decaBDE is present both in the workers and in persons from the control group. The decaBDE has however also been shown to be much less persistent than other PBDE congeners, with a half-life in humans of approximately 7 days, while a heptaBDE was shown to have a half-life of almost 3 months. TBBPA was also shown at low levels in human blood and to have a short half-life. Human exposure to OHS via intake of contaminated fish has been studied in a group of Latvian and Swedish men with highly interindividual consumption of fatty Baltic Sea fish. The OHS levels observed in serum were significantly related to both age and fish consumption for PCB and DDE but not for 2,2',4,4'-tetrabromodiphenyl ether, representing traditionally studied and newer OHS, respectively.Methods for reliable analysis of PBDEs, TBBPA and other BFRs have been developed. Improvements have been made in the clean-up procedure to minimize interferences, avoid adsorption to glass and to apply a highly specific identification mass spectrometric method. The instrumental analyses have been improved by making changes in sample application to the gas chromatographic system and choice of column for the separations. With these methods, it has also been possible to detect and quantify compounds with high molecular weights, e.g. decaBDE in both air and serum samples. A more relevant presentation of concentration data is suggested, based on molar mass instead of weight.
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| 416. |
- Tjerngren, Ida
(författare)
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Redefining the role of wetlands as methyl mercury sources : insights from wetlands before and after restoration
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Current literature identifies boreal wetlands as net sources for the potent neurotoxin methyl mercury (MeHg). Combined with national environmental aims of restoration of previously drained wetlands, there is a possible conflict between the ecological benefits of wetlands and their role as MeHg sources. This thesis presents a four-year study of seven Swedish boreal wetlands of different nutrient status subjected to restoration measures. Wetlands were characterized according to climate/geography, vegetation type and ancillary chemistry. Mercury (Hg) biogeochemistry was assessed by determination of proxies for long- and short-term net MeHg production rates in soils, i.e., %MeHg (of total Hg) and potential methylation and demethylation rate constants (km and kd). MeHg exports from each wetland catchment were calculated. In addition, each wetland was assessed as a net MeHg source or sink, based on mass balance budgets. Results follow similar patterns for %MeHg, km/kd and budgets among the wetlands. The nutrient status of the wetlands affect the net production of MeHg, with wetlands of intermediate nutrient status, i.e., poor-fen types of wetlands, having the highest %MeHg, km/kd and the largest net output of MeHg. MeHg budget results showed that six out of seven wetlands were net MeHg sources. The MeHg output varied more among wetlands, than before and after restoration measures of an individual wetland. This suggests that the nutrient status of a wetland is more important to the MeHg production than the performed restoration measures. A nutrient-rich Alnus glutinosa swamp was a net sink for MeHg during the entire study period. A spatial analysis along a gradient into the Alnus swamp showed an increased degradation of MeHg in the swamp soil. Snapshot budgets from nine additional swamps suggest that net degradation of MeHg is a general phenomenon for Alnus swamps. Results from this thesis have implications for forest managers and landscape planners. Previously drained wetlands can be restored based on informed decisions, avoiding restoration of poor-fen types of wetlands. In addition, Alnus swamps should be maintained and restored if possible, helping to mitigate the production of MeHg in boreal landscapes.
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| 417. |
- Valters, Karlis, 1970-
(författare)
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Assessment of organochlorine contamination in the aquatic environment of Latvia with perch and heron as biomarkers
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Polychlorinated biphenyls (PCBs), DDT, DDT transformation products, and several other organochlorine substances (OCS) have been analysed in numerous species and matrices from different parts of the world including Arctic environments. However, knowledge on levels and distribution of OCS is still lacking for many regions world-wide including the Eastern Europe in general. Hence the aim of this thesis is to evaluate the environmental situation concerning OCS in the aquatic environment of Latvia, as a part of the Eastern Baltic region. Two species - perch (Perca fluviatilis) and grey heron (Ardea cinerea) - were studied in detail as biomarkers of contaminant exposure.The effects of fish size, age, sex, and trophic positioning on the OCS concentrations in perch were investigated. There were no pronounced differences in OCS concentrations between the sexes. Perch up to a length of 20 cm showed no increase in contaminant concentrations with increased length, despite a clear raise in trophic positioning as shown by the analyses of stable nitrogen isotopes and gut contents. In perch exceeding 20 cm the concentrations increased with length. Thus perch below this length may be used as contaminant exposure biomarkers regardless of the omnivorous nature of the species.Further, to be able to measure OCS concentrations in a matrix at a higher trophic level than fish, the use of blood of grey heron chicks was evaluated. The chicks were sampled repeatedly, with a week in between, to investigate the contaminant concentration variation. The results showed that heron blood is a useful matrix for OCS exposure assessment. Blood sampling allows a nonbiased specimen for analysis and does not affect the birds' health. An optimal heron chicks' age for sampling of about three weeks is recommended.For the first time OCS contamination in the inland waters of Latvia is assessed. Lipid normalised total PCB concentrations in perch muscle from rural lakes were 200 to 600 ng/g. Conversely, somewhat higher PCB levels were determined in perch from some Riga lakes and the river mouth of Daugava. DDE concentrations were generally the highest of all individual OCS determined in the perch and heron samples. Bis(4-chlorophenyl) sulfone, DDT, DDD, hexachlorobenzene, hexachlorocyclohexanes, and trans-nonachlor were also analysed. On the whole, the OCS contamination is in the same range as in comparable samples from Swedish lakes and is generally similar to other parts of the Baltic Sea region.
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| 418. |
- von Stedingk, Hans, 1978-
(författare)
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Methodology for hemoglobin adduct measurement : Fetal exposures to acrylamide and other genotoxic agents
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is increasing evidence that exposure to toxic chemicals during the prenatal period constitute a higher health risk than exposure during adulthood. To characterize exposure and identify risk factors, sensitive methods for analysis of chemicals in vivo with biomarker methods are needed. Adducts to hemoglobin (Hb) have been shown useful as biomarkers of dose in blood of reactive compounds/metabolites, which are toxic due to reactions with biomacromolecules. The aim of this thesis was to develop a new method for the analysis of Hb adducts suitable for analysis of large sample series, and then to apply the method for measurements of Hb adducts from exposure to acrylamide, glycidamide and ethylene oxide in mother/cord blood samples from five European countries. A new method for measurements of N-terminal Hb adducts, denoted the adduct FIRE procedure, was developed using the fluorescein isothiocyanate Edman reagent. With the new procedure, optimized for LC/MS analysis, a high sensitivity and reproducibility was achieved. The new method made it possible to perform measurements of low exposures to the studied genotoxic compounds in approximately 1350 maternal and cord blood samples. The results show that the fetus is exposed to a similar in vivo dose of the studied compounds as the mother. The measured Hb adduct levels show that acrylamide exposure from food intake is higher for the participating mothers fromUK compared to the mothers from the other countries. The measured Hb adduct levels form a basis for evaluations of relationships between exposure and health risks, and ongoing studies indicate associations between acrylamide Hb adduct levels and birth weight. The developed method was also used for identification of an unknown Hb adduct, which was shown to originate from methyl vinyl ketone (MVK), a highly reactive and toxic compound. The identity of the adduct was confirmed with synthesized standards. There exist both natural and anthropogenic sources to MVK, and to what extent the MVK-adduct reflects exogenous exposure is yet not clarified.
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| 419. |
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| 420. |
- Westberg, Emelie, 1979-
(författare)
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Biomarkers of internal exposure/dose : Methods to quantify adducts to protein and DNA by LC/MS studied with benzo[a]pyrene and isocyanates
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on methods for quantification by liquid chromatography/mass spectrometry (LC/MS) of specific biomarkers for internal dose of chemicals which induce toxicity through their electrophilic reactivity. In vivo such compounds are short-lived, and could feasibly be measured as their reaction products (adducts) with biomacromolecules. Analysis by MS methods of stable adducts offers the specificity and accuracy required to generate data on internal dose useful in risk estimation.The primary aim was to develop a method for quantification by LC/MS of bulky adducts to serum albumin (SA) from polycyclic aromatic hydrocarbons, using the genotoxic diolepoxide (DE) of benzo[a]pyrene (BP) as a model. A method for analysis of the BPDE adducts to His146 in SA was developed which is robust, easy-to-use, has good reproducibility and which reached a high sensitivity. A method for quantification of BPDE adducts to N2-deoxyguanosine (dG) in DNA by LC/MS was also established.In mice exposed to BP, adducts to SA and DNA from stereoisomers of BPDE were identified and quantified. The adduct level was shown to be >400 times higher in DNA than in SA, which from an in vitro study could be concluded to mainly depend on a large difference in the rates of adduct formation to His in SA and to dG in DNA. BPDE adduct levels to SA and DNA, and a biomarker of genotoxic effect (frequency of micronuclei), were compared in BP-exposed mice. The results were used to evaluate how these methods could be used in procedures for cancer risk estimation.An LC/MS method for analysis of valine hydantoins (VH) formed as adducts from isocyanates to N-termini in haemoglobin was established. VH, formed from urea/isocyanic acid, was investigated in mice as a potential biomarker of renal failure and for dose adjustment during treatment with a radioactive cytostatic drug. The kidney dysfunction was not severe enough to give a significant increase of VH in the experiment.
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