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  • 51.
    Bergqvist, Magnus
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Methods for the characterization of triacylglycerol and glycoglycerolipid molecular species1995Doctoral thesis, comprehensive summary (Other academic)
  • 52.
    Bergvall, C
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Westerholm, R
    Accelerated Solvent Extraction for Determination of Benzo(a)pyrene in Diesel Particulate Matter2007In: NOSA Aerosol Symposium, 2007Conference paper (Other (popular science, discussion, etc.))
  • 53.
    Bergvall, C
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Westerholm, R
    Evaluation of Accelerated Solvent Extraction of deuterated benzo(a)pyrene and dibenzo(a,i)pyrene from Diesel Standard Reference Material 29752007In: ISPAC 2007, 2007Conference paper (Other (popular science, discussion, etc.))
  • 54.
    Bergvall, Christoffer
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Determination of dibenzopyrenes in standard reference materials (SRM) 1649a, 1650, and 2975 using ultrasonically assisted extraction and LC-GC-MS2006In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 384, no 2, p. 438-447Article in journal (Refereed)
    Abstract [en]

    A method has been developed for analysis of the highly potent polycyclic aromatic hydrocarbon (PAH) carcinogens dibenzo(a,l)pyrene, dibenzo(a,h)pyrene and dibenzo(a,i)pyrene (molecular weight 302) present in small amounts in diesel and air particulate materials. The method can also be used for analysis of the PAH benzo(a)pyrene, coronene and perylene, for which reference and certified values are available for the Standard Reference Materials used for validation of the method: SRM 1649a (Urban dust) and SRM 2975 (Diesel particulate matter). The only NIST values that have been published for these dibenzopyrene isomers in the analyzed SRMs are reference values for dibenzo(a,i)pyrene and dibenzo(a,h)pyrene in SRM 1649a. The concentrations determined in the SRMs were in good agreement with reported NIST-certified and reference values and other concentrations reported in the literature. The Standard Reference Material 1650 (Diesel particulate matter) was also analyzed. The method could not, however, be validated using this material because certification of SRM 1650 had expired. The method is based on ultrasonically-assisted extraction of the particulate material, then silica SPE pre-separation and isolation, and, separation and detection by hyphenated LC-GC-MS. The method is relatively rapid and requires only approximately 1-5 mg SRM particulate material to identify and quantify the analytes. Low extraction recoveries for the analytes, in particular the dibenzopyrenes, when extracting diesel SRMs 2975 and 1650 resulted, however, in the dibenzopyrenes being present in amounts near their limit of quantifications in these samples. The method’s limit of quantification (LOQ), based on analyses of SRM 1649a, is in the range of 10-77 pg. By use of this method more than 25 potential PAH isomers with a molecular weight of 302 could be separated.

  • 55.
    Bergvall, Christoffer
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Methods for Determination of Benzo(a)pyrene and High Molecular Weight (>300 Da) Polycyclic Aromatic Hydrocarbons in Particulate Matter from Ambient Air and Vehicle Exhausts2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Air pollution with particulate matter (PM) raises considerable concern because of its adverse effects on human health. For this reason, and because the mechanisms of PM toxicity are not fully known, there is an urgent need to determine the chemical constituents of atmospheric PM, especially PM emanating from traffic - a major source of urban PM.

    This thesis describes analytical methods that have been developed for determining polycyclic aromatic hydrocarbons (PAHs) in ambient air and vehicle exhaust PM, focusing particularly on benzo(a)pyrene (B(a)P) and the dibenzopyrenes: dibenzo(a,l)pyrene, dibenzo(a,e)pyrene, dibenzo(a,i)pyrene and dibenzo(a,h)pyrene. Trace amounts in complex matrices have been met by coupling parts or the entire clean-up step using liquid chromatography on-line with the analysis step using gas chromatography-mass spectrometry into one automated system.

    Application of the methodology, using either ultrasonic assisted extraction (USE) or accelerated solvent extraction (ASE), to a National Institute of Standards and Technology (NIST) urban air standard reference material (SRM) yielded comparable or higher concentrations than the assigned NIST values, validating the approach. However, ASE provided higher extraction yields from diesel particulate SRMs than USE, and ASE of diesel SRMs generally yielded higher concentrations than the corresponding NIST values.

    Concentrations of dibenzopyrenes in Stockholm air PM, and gasoline- and diesel-fuelled vehicle emissions (ng/km), are reported for the first time. When adjusted in terms of their relative carcinogenic potencies, the dibenzopyrenes were found to pose greater carcinogenic hazards than B(a)P, indicating that the current use of B(a)P as a marker probably leads to underestimates of the carcinogenicity of PAHs in ambient air.

    The developed methods also worked well for analyzing larger molecular weight PAHs: more than 60 and 170 potential PAHs were detected in ambient air PM and diesel PM, respectively.

  • 56.
    Bergvall, Christoffer
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Determination of 252-302 Da and tentative identification of 316-376 Da polycyclic aromatic hydrocarbons in Standard Reference Materials 1649a Urban Dust and 1650b and 2975 Diesel Particulate Matter by accelerated solvent extraction-HPLC-GC-MS.2008In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 391, no 6, p. 2235-2248Article in journal (Refereed)
    Abstract [en]

    We have assessed and compared the extraction recoveries of polycyclic aromatic hydrocarbons (PAHs) with molecular weights of 252, 276, 278, 300 and 302 from diesel particulate matter (PM) and urban air particles using ultrasonically-assisted extraction and accelerated solvent extraction methods, and evaluated the effects of sample and treatment parameters. The results show that accelerated solvent extraction can extract PAHs more efficiently from diesel PM than ultrasonically assisted extraction. They also show that PAHs are more difficult to extract from diesel PM than from urban air particles. Using toluene and maximum instrumental settings (200 ºC, 3000 psi and five extraction cycles) with 30 min static extraction times > 85 % of the analytes were estimated to be extracted from the diesel particles, but four extraction cycles with just 5 min static extraction times under these conditions seems to be sufficient to extract > 95 % of the analytes from the urban air particles. The accelerated solvent extraction method was validated using Standard Reference Materials (SRM) 1649a, Urban Dust, SRM 2975 and SRM 1650a, Diesel Particulate Matter, from the US National Institute of Standards and Technology (NIST). PAH concentrations determined by on-line high performance liquid chromatography-gas chromatography-mass spectrometry following the developed accelerated solvent extraction method were generally higher than the certified and reference NIST values and concentrations reported in the literature (e.g. the estimated concentration of benzo(a)pyrene in SRM 2975 was 15-fold higher than the NIST-certified value), probably because the extraction recoveries were higher than in previous studies. The developed accelerated solvent extraction method was used to analyze high molecular weight PAHs (Mw>302) in the investigated SRMs, and more than 170 (SRM 1649a), 80 (SRM 1650b) and 60 (SRM 2975) potential high molecular weight PAHs were tentatively identified in them, with molecular weights (depending on the SRM sample analysed) of 316, 326, 328, 340, 342, 350, 352, 366, 374 and 376. This is, to our knowledge, the first study to tentatively report PAHs with molecular weights of 316, 326, 328, 342, 350, 352, 366 and 374 in diesel particulate matter. GC-MS chromatograms obtained in selected ion monitoring mode (extracted ions for the above mentioned m/z) and full-scan mass spectra of tentatively identified high molecular weight PAHs are shown in the electronical supplementary material.

  • 57.
    Bergvall, Christoffer
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Determination of highly carcinogenic dibenzopyrene isomers in particulate emissions from two diesel- and two gasoline-fuelled light-duty vehicles2009In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 43, no 25, p. 3883-3890Article in journal (Refereed)
    Abstract [en]

    Emission factors of particulate-bound Polycyclic Aromatic Hydrocarbons (PAHs) including benzo(a)pyrene and, for the first time, the highly carcinogenic dibenzo(a,l)pyrene, dibenzo(a,e)pyrene, dibenzo(a,i)pyrene and dibenzo(a,h)pyrene have been determined in exhausts from two diesel- (DFVs) and two gasoline-fuelled light-duty vehicles (GFVs) operated in the Urban (AU), Rural Road (AR) and Motorway (AM) transient ARTEMIS driving cycles. The obtained results showed the DFVs to emit higher amounts of PAHs than the GFVs per km driving distance at low average speed in the AU driving cycle, while the GFVs emitted higher amounts of PAHs than the DFVs per km driving distance at higher average speeds in the AR and AM driving cycles. Furthermore, the study showed an increase in PAH emissions per km driving distance with increasing average speed for the GFVs with the opposite trend found for the DFVs. The GFVs generated particulate matter with higher PAH content than the DFVs in all three driving cycles tested with the highest concentrations obtained in the AR driving cycle. Dibenzo(a,l)pyrene was found to be a major contributor to the potential carcinogenicity accounting for 58–67% and 25–31% of the sum added potential carcinogenicity of the measured PAHs in the emitted particulate matter from the DFVs and GFVs, respectively. Corresponding values for benzo(a)pyrene were 16–25% and 11–40% for the DFVs and GFVs, respectively. The DFVs displayed higher sum added potential carcinogenicity of the measured PAHs than the GFVs in the AU driving cycle with the opposite trend found in the AR and AM driving cycles. The findings of this study show the importance of including the dibenzopyrenes in vehicle exhaust chemical characterizations to avoid potential underestimation of the carcinogenic activity of the emissions. The lower emissions and the lower sum added potential carcinogenicity of the measured PAHs found in this study for the GFVs compared to the DFVs in the AU driving cycle indicate the GFVs to be preferred in dense urban areas with traffic moving at low average speeds with multiple start and stops. However, the obtained results suggest the opposite to be true at higher average speeds with driving at rural roads and motorways. Further studies are, however, needed to establish if the observed differences between GFVs and DFVs are generally valid as well as to study the effects on variations in vehicle/engine type, ambient temperature, fuel and driving conditions on the emission factors.

  • 58.
    Bergvall, Christoffer
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Westerholm, Roger
    Identification and Determination of Highly Carcinogenic Dibenzopyrene Isomers in Air Particulate Samples from a Street Canyon, a Rooftop, and a Subway Station in Stockholm2007In: Environmental Science & Technology, ISSN 0013-936X, Vol. 41, no 3, p. 731-737Article in journal (Refereed)
    Abstract [en]

    This study presents determined levels of the highly carcinogenic dibenzopyrene isomers dibenzo(a,l)pyrene, dibenzo(a,e)pyrene, dibenzo(a,i)pyrene, and dibenzo(a,h)pyrene as well as three other polycyclic aromatic hydrocarbons (PAHs)benzo(a)pyrene, perylene and coronenein ambient particulate material samples from a street canyon, a rooftop, and an underground subway station in Stockholm, Sweden. To our knowledge, these are the first reported determinations of dibenzopyrene isomers in air particles from either Stockholm or a subway station. Taking into account both concentration and toxic equivalence factors (TEFs), the PAH with the highest carcinogenic potency in the analyzed samples was dibenzo(a,l)pyrene, and the sum carcinogenic potency of the determined dibenzopyrenes was about 1−4 times higher than that of benzo(a)pyrene in the analyzed samples. These findings indicate that it is important to analyze the dibenzopyrene isomers as well as benzo(a)pyrene; the common approach of using benzo(a)pyrene as an indicator substance could lead to underestimates of the potential carcinogenic potency of PAHs in ambient air. The results also indicate that the relative carcinogenic potency of the determined dibenzopyrenes and benzo(a)pyrene in air particles from Stockholm is similar to that of air particles sampled in Washington in 1976−1977, despite general improvements in air quality in the intervening period. However, more data are needed to characterize temporal variations in dibenzopyrene levels in locations such as subway stations, suburbs, road tunnels, and metropolitan areas. There is also a need to identify and characterize both stationary and mobile PAH sources with respect to emission of dibenzopyrene isomers.

  • 59.
    Bergvall, Christoffer
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Polycyclic Aromatic Hydrocarbons (PAHs) with molecular weights > 252 u in particulate matter originating from a domestic heating system fuelled with wheat2009Conference paper (Other academic)
    Abstract [en]

    Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous environmental pollutants formed during the incomplete combustion of organic matter in air. PAHs with molecular weights (Mw) < 302 u have previously been determined in particulate matter originating from combustion of wheat. However, no studies exist in the literature on determination of high molecular weight (HMW) PAHs i.e. with Mw ≥ 302 u in particulate matter from wheat combustion. The particulate matter used in the present study was sampled from the exhausts generated from a 20 kW multi fuel boiler designed for the use of various bio-fuels such as cereals, wood pellets and wood chips (Baxi combi heath 2.5, Baxi, Sweden). The particulate matter was analyzed using the same method that previously has been used by our group to detect HMW PAHs in urban air particulate matter and diesel particulates. The particulate matter was extracted with toluene using Accelerated Solvent Extraction (ASE), cleaned up using silica solid phase extraction (SPE) cartridges and analyzed using on-line hyphenated High Performance Liquid Chromatography (HPLC)-Gas Chromatography (GC)-Mass Spectrometry (MS).This study presents for the first time quantitative data of the dibenzopyrene isomers (Mw 302 u) dibenzo(a,l)pyrene, dibenzo(a,e)pyrene, dibenzo(a,i)pyrene and dibenzo(a,h)pyrene as well as full scan mass spectra of tentatively identified HMW PAHs with Mw of 314 u, 316 u, 324 u, 326 u, 328 u, 340 u, 350 u, 352 u and 374 u detected in particulate matter from domestic heating using wheat as fuel. Comparisons are made with a recent publication in which we presented full scan mass spectra of HMW PAHs detected in the Standard Reference Materials (SRMs) 1649a Urban Dust and 1650b and 2975 Diesel Particulate Matter obtained from the National Institute of Standards and Technology (NIST). The mean amount of PAHs (Mw 252 u-302 u) found in the wheat combustion generated particulate matter was approximately a factor 3 and 6 times higher than what we have previously found in particulate matter originating from modern and older diesel engines, respectively. Björn Holstensson is acknowledged for providing the multi fuel boiler. Stefan Gustavsson and Lena Elfver are acknowledged for skillful sampling and laboratory work. The research project is financed by Stockholm University and Härseby farm.

  • 60. Bjurshammar, N
    et al.
    Buhlin, K
    Tranæus, S
    Johannsen, A
    Östman, Conny
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    On the Red Fluorescence Emission of Aggregatibacter actinomycetemcomitans2012In: Open Journal of Stomatology, ISSN 2160-8709, no 2, p. 299-306Article in journal (Refereed)
    Abstract [en]

    A number of studies have indicated that bacteria able to emit red fluorescence can be detected by light in-duced fluorescence technique and killed by photody-namic therapy. The objective of this study was to in-vestigate the red fluorescence properties of the single gram negative capnophilic bacterium Aggregatibacter actinomycetemcomitans, ATCC 33384, and to investi-gate if these properties were related to the growth, morphology and size of the bacterial colonies. Time trend assessment was made with red fluorescence by QLF (Quantitative Light-induced Fluorescence), as well as with white light digital imaging. It was dem-onstrated that A. actinomycetemcomitans, a single cap-nophilic bacterium, is able to produce red fluores-cence on its own, i.e. in the absence of other bacteria strains, and that blood agar is necessary to obtain red fluorescence from this bacterium on culture plates. This bacterium formed smooth circular, bell/dome like colonies increasing in size with time exhibiting various red fluorescence behaviors. A large variation in the fluorescence behavior points out an inhomoge-neous distribution of red fluorescence within and be-tween the colonies, i.e. the size of the investigated colonies did not correlate with the red fluorescence area, suggesting a dependence on the colony mor-phology such as the colony growth in height. To our knowledge this is the first study that have shown that A. actinomycetemcomitans on its own is able to pro-duce fluorescence in the red spectral region.

  • 61.
    Björklund, Jonas
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Gas chromatography and mass spectrometry of polybrominated diphenyl ethers2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [sv]

    The aim of this thesis has been to develop accurate and sensitive analytical methods for the determination of polybrominated diphenyl ethers (PBDEs). It focuses on the development and optimization of gas chromatographic and mass spectrometric analysis of PBDE.

    PBDEs are widely used as additative flame retardants and an increasing environmental occurrence and persistence rise concern about these compounds as environmental contaminants. However, the chemical and physical properties of the PBDEs yield a number of problems associated with the analysis of these compounds. This thesis provides an overview of the gas chromatographic separation system used for determination of PBDE and suggestions of improvements of the analytical methods. It is shown that by careful selection and optimization of the injection technique, the column system and the detection technique, the precision of the analytical method for PBDEs is significantly improved.

    To increase sensitivity and overcome some of the problems associated with sample preparation, large volume injection technique is recommended. Both large volume programmable temperature vaporizing (PTV) injection and the loop type injector has been optimized and evaluated with respect to the PBDEs. It is also demonstrated that the GC injection technique most commonly used for PBDE analysis, discriminate the high molecular weight congeners such as the decabrominated diphenyl ether congener (BDE-209).

    The dimensions and the type of GC column system strongly affect the yield of the PBDE. Degradation in the GC system of high molecular weight polybrominated diphenyl ether (BDE) congeners, especially BDE-209, is also dependent on the residence time in the column system. There is a large difference in performance between columns with supposedly similar stationary phase and by selecting a short narrow bore columns it is possible to dramatically decrease the degradation of high molecular weight PBDEs.

    Mass spectrometric properties of BDE-209 is presented, and carbon 13 labeled BDE-209 is evaluated and proposed as internal surrogate standard for the determination of BDE-209 in mass spectrometric detection in electron capture negative ionization (ECNI) mode.

  • 62. Björklund, Jonas
    et al.
    Isetun, Sindra
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nilsson, Ulrika
    Selective determination of organophosphate flame-retardants and plasticizers in indoor air by gas chromatography, positive-ion chemical ionization and collision-induced dissosiation mass spectrometry2004In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 18, no 24, p. 3079-3083Article in journal (Refereed)
    Abstract [en]

    Gas chromatography/ion trap mass spectrometry with in-source ionization and dissociation was used in positive-ion chemical ionization (PICI) mode for the determination of organophosphate triesters in indoor air. These compounds are widely used as additive flame retardants and plasticizers in different types of materials and have become ubiquitous pollutants in indoor environments. When using collision-induced dissociation in PICI mode the fragmentation of the organophosphate triesters can be performed in a more controllable way than in electron ionization (EI) mode. The developed selected-reaction monitoring method provided high selectivity for the investigated compounds. For 8-h air measurements (corresponding to 1.5 m3 of sampled air) the limit of detection of the method was determined to be in the range 0.1–1.4 ng m−3, which is comparable with nitrogen-phosphorus detection and about 50-fold lower than when using EI in selected-ion monitoring mode. The presented method was applied to samples from three common indoor environments, in which a number of organophosphate triesters were identified and quantified. The dominating compound was found to be tris(2-chloropropyl) phosphate, which occurred at levels up to 0.8 μg m−3.

  • 63. Björklund, Jonas
    et al.
    Tollbäck, Petter
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Hiärne, Christian
    Dyremark, Eva
    Östman, Conny
    Influence of the injection technique and column system on gas chromatographic determination of polybrominated diphenyl ethers (PBDE)2004In: Journal of Chromatography A, ISSN 0021-9673, Vol. 1041, no 1-2, p. 201-210Article in journal (Refereed)
  • 64. Björklund, Jonas
    et al.
    Tollbäck, Petter
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Östman, Conny
    Large volume injection GC-MS in electron capture negative ion mode utilizing isotopic dilution for the determination of polybrominated diphenyl ethers in air2003In: Journal of Separation Science, ISSN 1615-9306, Vol. 26, no 12-13, p. 1103-1110Article in journal (Refereed)
  • 65. Björklund, Jonas
    et al.
    Tollbäck, Petter
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Östman, Conny
    Mass spectrometric characteristics of decabromodiphenyl ether and the application of isotopic dilution in the electron capture negative ionization mode for the analysis of polybrominated diphenyl ethers2003In: Journal of Mass Spectrometry, ISSN 1096-9888, Vol. 38, no 4, p. 394-400Article in journal (Refereed)
  • 66. Blomqvist, Per
    et al.
    McNamee, Margaret Simonson
    Stec, Anna A.
    Gylestam, Daniel
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Karlsson, Daniel
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Detailed study of distribution patterns of polycyclic aromatic hydrocarbons and isocyanates under different fire conditions2014In: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 38, no 1, p. 125-144Article in journal (Refereed)
    Abstract [en]

    This study has examined the distribution patterns between gas phase and particle phase of some chemical compounds produced in fires. It has also addressed the question of the distribution of individual particle-associated species between the different size-ranges of particles. The chemical compounds studied and discussed in this paper are polycyclic aromatic hydrocarbons (PAHs), and isocyanates. The steady-state tube furnace, ISO/TS 19700, was chosen as the physical fire model in order to study the production of particles from different types of fire exposure, that is, oxidative pyrolysis, well-ventilated flaming fires and under-ventilated flaming post-flashover fires. Two materials were chosen for investigation, a polyvinyl chloride (PVC) carpet and a wood board. The particle production from the two materials investigated varied concerning both the amounts produced and the particle size distributions. The analysis of PAHs showed that volatile PAHs were generally dominant. However, when the toxicity of the individual species was taken into account, the relative importance between volatile and particle-associated PAHs shifted the dominance to particle-bound PAH for both materials. The substantial degradation in the tests of the low polyurethane content of the PVC carpet, and the (4,4-methylenediphenyl diisocyanate)-based binder in the wood board resulted in no or very small amount of quantifiable diisocyanates.

  • 67. Blomqvist, Per
    et al.
    Simonson McNamee, Margaret
    Stec, Anna A.
    Gylestam, Daniel
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Karlsson, Daniel
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Characterisation of fire generated particles: BRANDFORSK project 700-061, FireTechnology, SP Report 2010:012010Report (Other academic)
    Abstract [en]

    Characterisation of fire generated particles

    The present project has examined the question of distribution patterns of important chemical compounds between gas phase and particle phase. It has also, in some cases, addressed the question of the distribution of individual particle-associated species between the different size-ranges of particles produced in a fire. The chemical compounds studied were hydrogen chloride (HCl), polycyclic aromatic hydrocarbons (PAHs), and isocyanates.

    The steady-state tube furnace, ISO/TS 19700, was chosen as the physical fire model in order to study the production of particles from different types of fire exposure. Three different fire types were investigated: oxidative pyrolysis, well-ventilated flaming fires and vitiated post flashover. Two materials were chosen for investigation, PVC-carpet and wood board, based on their prevalence fire exposure scenarios and their chemical composition. The particle production from the two materials investigated varied both concerning the amounts produced and the particle size distributions. The production of particles on a mass basis was generally significantly lower from the wood board compared with the PVC-carpet. The tests with the PVC-carpet showed that relatively large particles are produced from all combustion conditions examined. The tests made with the wood board show preferably predisposition towards the production of small-sized particles during flaming combustion.

    The analysis of PAHs in the tests with the PVC-carpet showed that volatile PAHs were dominate during all types of combustion. However, when the toxicity of the individual species was taken into account, the relative importance between volatile and particle associated PAHs changed. From the tests with the wood board material (OSB) it was noted that the highest yields of total PAHs were found from under ventilated conditions, and the volatile part of the total PAH dominated for this material as well. The yields found from the well-ventilated tests were very low. Toxicity weighted data showed that the particle associated part dominated the toxicity both for under ventilated and well-ventilated conditions.

    A study made of the presence of chlorine on particles showed that it is clear that the major part of the HCl produced during combustion of the PVC-carpet is present in the gas phase. Chlorine was found associated with particulates but these results were, however, inconclusive due to the difficulty in determining the source of the chlorine found in the soot fractions studied.

    The low polyurethane (PUR) content and the substantial degradation of the PUR in the tests resulted in no or very small amounts of quantifiable isocyanate dimers (i.e. high molecular species). Monoisocyanates such as ICA and MIC dominated in the emitted degradation products. These kinds of monoisocyanates are volatile compounds and almost exclusively present in the gas phase.

     

  • 68. Boman, C
    et al.
    Forsberg, B
    Sandström, T
    Sehlstdt, M
    Westerholm, R
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    The Role of Particle Size and Chemical Composition for Health Effects-A Review of the Current Literature. Report to Swedish Emission Research Project (EMFO)2007Report (Other academic)
  • 69. Boman, Christoffer
    et al.
    Pettersson, Esbjorn
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Bostrom, Dan
    Nordin, Anders
    Stove Performance and Emission Characteristics in Residential Wood Log and Pellet Combustion, Part 1: Pellet Stoves2011In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 25, p. 307-314Article in journal (Refereed)
    Abstract [en]

    Stove performance, characteristics, and quantities of gaseous and particulate emissions were determined for two different pellet stoves, varying fuel load, pellet diameter, and chimney draft. This approach aimed at covering variations in emissions from stoves in use today. The extensive measurement campaign included CO, NO(x), organic gaseous carbon, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PM(tot)) as well as particle mass and number concentrations, size distributions, and inorganic composition. At high load, most emissions were similar. For stove B, operating at high residual oxygen and solely with primary air, the emissions of PM,, and particle numbers were higher while the particles were smaller. Lowering the fuel load, the emissions of CO and hydrocarbons increased dramatically for stove A, which operated continuously also at lower fuel loads. On the other hand for stove B, which had intermittent operation at lower fuel loads, the emissions of hydrocarbons increased only slightly lowering the fuel load, while CO emissions increased sharply, due to high emissions at the end of the combustion cycle. Beside methane, dominating VOCs were ethene, acetylene, and benzene and the emissions of VOC varied in the range 1.1-42 mg/MJ(fuel). PAH emissions (2-340 mu g/MJ(fuel)) were generally dominated by phenanthrene, fluoranthene and pyrene. The PM(tot) values (15-45 mg/MJ(fuel)) were in all cases dominated by fine particles with mass median diameters in the range 100-200 nm, peak mobility diameters of 50-85 nm, and number concentrations in the range 4 x 10(13) to 3 x 10(14) particles/MJ(fuel). During high load conditions, the particulate matter was totally dominated by inorganic particles at 15-25 mg/MJ(fuel) consisting of potassium, sodium, sulfur, and chlorine, in the form of K(2)SO(4), K(3)Na(SO(4))(2), and KCl. The study shows that differences in operation and modulation principles for the tested pellet stoves, relevant for appliances in use today, will affect the performance and emissions significantly, although with lower scattering in the present study compared to compiled literature data.

  • 70. Campone, Luca
    et al.
    Piccinelli, Anna Lisa
    Östman, Conny
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Rastrelli, Luca
    Determination of organophosphorous flame retardants in fish tissues by matrix solid-phase dispersion and gas chromatography2010In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650Article in journal (Refereed)
  • 71.
    Carlsson, Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    von Stedingk, Hans
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nilsson, Ulrika
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Törnqvist, Margareta
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    LC–MS/MS Screening Strategy for Unknown Adducts to N-Terminal Valine in Hemoglobin Applied to Smokers and Nonsmokers2014In: Chemical Research in Toxicology, ISSN 0893-228X, E-ISSN 1520-5010, Vol. 27, no 12, p. 2062-2070Article in journal (Refereed)
    Abstract [en]

    Electrophilically reactive compounds have the ability to form adducts with nucleophilic sites in DNA and proteins, constituting a risk for toxic effects. Mass spectrometric detection of adducts to N-terminal valine in hemoglobin (Hb) after detachment by modified Edman degradation procedures is one approach for in vivo monitoring of exposure to electrophilic compounds/metabolites. So far, applications have been limited to one or a few selected reactive species, such as acrylamide and its metabolite glycidamide. This article presents a novel screening strategy for unknown Hb adducts to be used as a basis for an adductomic approach. The method is based on a modified Edman procedure, FIRE, specifically developed for LC-MS/MS analysis of N-terminal valine adducts in Hb detached as fluorescein thiohydantoin (FTH) derivatives. The aim is to detect and identify a priori unknown Hb adducts in human blood samples. Screening of valine adducts was performed by stepwise scanning of precursor ions in small mass increments, monitoring four fragments common for the FTH derivative of valine with different N-substitutions in the multiple-reaction mode, covering a mass range of 135 Da (m/z 503-638). Samples from six smokers and six nonsmokers were analyzed. Control experiments were performed to compare these results with known adducts and to check for artifactual formation of adducts. In all samples of smokers and nonsmokers, seven adducts were identified, of which six have previously been studied. Nineteen unknown adducts were observed, and 14 of those exhibited fragmentation patterns similar to earlier studied FTH derivatives of adducts to valine. Identification of the unknown adducts will be the focus of future work. The presented methodology is a promising screening tool using Hb adducts to indicate exposure to potentially toxic electrophilic compounds and metabolites.

  • 72.
    Claeson Bohnstedt, Kristina
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Determination of biomarkers for lipid peroxidation and oxidative stress: Development of analytical techniques and methods2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Oxidative stress can be defined as a state of disturbance in the pro-oxidant/antioxidant balance in favour of the former, leading to potential damage. Processes associated with oxidative stress involve reactive oxygen species and radicals and can result in elevated levels of oxidatively modified or toxic molecules that can cause cellular malfunction, and even cell death. Destruction of membrane lipids, lipid peroxidation, caused by reactive oxygen species and radicals has been coupled to many diseases and also normal ageing.

    The measurement of low molecular weight biomarkers of oxidative stress present in complex matrices such as brain tissue, plasma, urine or cerebrospinal fluid is a delicate and difficult task and there is a need for improved analytical tools in this field of research.

    The major foci of this thesis and the work underlying it are the development of analytical techniques and methods for determining biomarkers for oxidative stress and lipid peroxidation. Aspects of particular concern include the effects of sample treatments prior to analysis, evaluation of the developed methods with respect to possible artefacts, and the scope for results to be misinterpreted. The specific research goals and issues addressed are detailed in five papers, which this thesis is based upon.

    Paper I focuses on malondialdehyde, describing and evaluating two new simplified sample pre-treatment regimes for the determination of malondialdehyde in rat brain tissue by capillary electrophoresis with UV detection. The effects of sample storing and handling are also considered.

    Paper II describes the synthesis, characterization and implementation of a new internal standard for the determination of malondialdehyde in biological samples using electrophoretic or chromatographic separation techniques. The usefulness of the internal standard is demonstrated in analyses of rat brain tissue samples.

    Paper III presents a method for the determination of 4-hydroxynon-2-enal in brain tissue from rats employing micellar electrokinetic chromatography separation and laser-induced fluorescence detection.

    Paper IV is focused on the development of a new methodology for determining the stereoisomeric F2-isoprostanes in human urine samples employing chromatographic separation on porous graphitic carbon and detection by electrospray ionization-tandem mass spectrometry. The results from this study conflict with the hypothesis that peripheral isoprostanes are elevated in patients with Alzheimer’s disease.

    Paper V describes porous graphitic carbon chromatography-tandem mass spectrometry for the determination of isoprostanes in human cerebrospinal fluid. A new simplified sample pre-treatment regime, involving a column switching technique, is presented that allows direct injection of a relatively large volume of CSF into the chromatographic system.

  • 73.
    Claeson Bohnstedt, Kristina
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Karlberg, Bo
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Basun, Hans
    Schmidt, Staffan
    Porous graphitic carbon chromatography-tandem mass spectrometry for the detection of isoprostanes in human cerebrospinal fluid2005In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 827, no 1, p. 39-43Article in journal (Refereed)
    Abstract [en]

    F2-isoprostanes are produced by the non-enzymatic peroxidation of arachidonic acid in membrane phospholipids. This paper describes a new method for the determination of all four classes of F2-isoprostanes in human cerebrospinal fluid (CSF) involving separation on a 1 mm × 150 mm porous graphitic carbon (PGC) column and detection by triple quadrupole mass spectrometry in negative-ion electrospray mode. The sample pre-treatment consisted of an ultrafiltration step, following which 300 μl of CSF sample could be injected directly onto a 1 mm × 10 mm PGC guard column functioning as a trap for the analytes. The loading solvent was Milli-Q water at 125 μl/min. After 3 min, the sample was switched into the separation column. The F2-isoprostanes were separated in 20 min using a linear solvent gradient comprising water, methanol, acetonitrile and ammonium hydroxide at a pH of 9.5 and a flow of 50 μl/min The limit of detection (calculated as 3S/N) was approximately 40 pM (14 pg/ml). The assay was linear within the examined range (18–450 pg/ml), using CSF spiked with iPF2α-III standard (r2 > 0.995). Repeatability data were calculated for CSF spiked to 90 pg/ml and the relative standard deviation (RSD) obtained was 3% (n = 6).

  • 74.
    Claeson Bohnstedt, Kristina
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Karlberg, Bo
    Wahlund, Lars-Olof
    Eriksdotter Jönhagen, Maria
    Basun, Hans
    Schmidt, Staffan
    Determination of isoprostanes in urine samples from Alzheimer patients using porous graphitic carbon liquid chromatography-tandem mass spectrometry2003In: Journal of Chromatography B, Vol. 796, no 1, p. 11-19Article in journal (Refereed)
  • 75.
    Claeson, Kristina
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Micellar electrokinetic chromatography separation and laser induced fluorescence detection of the lipid peroxidation product 4-hydroxynonenal2001In: Journal of Chromatography B, ISSN 1387-2273, Vol. 763, no 1-2, p. 133-138Article in journal (Refereed)
  • 76.
    Claeson, Kristina
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Thorsén, Gunnar
    Karlberg, Bo
    Methyl malondialdehyde as an internal standard for the determination of malondialdehyde2001In: Journal of Chromatography B, ISSN 1387-2273, Vol. 751, no 2, p. 315-323Article in journal (Refereed)
  • 77.
    Claeson, Kristina
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Åberg, Fredrik
    Karlberg, Bo
    Free malondialdehyde determination in rat brain tissue by capillary zone electrophoresis: evaluation of two protein removal procedures2000In: Journal of Chromatography B, ISSN 1387-2273, Vol. 740, no 1, p. 87-92Article in journal (Refereed)
  • 78. Conley, Christopher J.
    et al.
    Smith, Rob
    Torgrip, Ralf
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Taylor, Ryan M.
    Tautenhahn, Ralf
    Prince, John T.
    Massifquant: open-source Kalman filter-based XC-MS isotope trace feature detection2014In: Bioinformatics, ISSN 1367-4803, E-ISSN 1367-4811, Vol. 30, no 18, p. 2636-2643Article in journal (Refereed)
    Abstract [en]

    Motivation: Isotope trace (IT) detection is a fundamental step for liquid or gas chromatography mass spectrometry (XC-MS) data analysis that faces a multitude of technical challenges on complex samples. The Kalman filter (KF) application to IT detection addresses some of these challenges; it discriminates closely eluting ITs in the m/z dimension, flexibly handles heteroscedastic m/z variances and does not bin the m/z axis. Yet, the behavior of this KF application has not been fully characterized, as no cost-free open-source implementation exists and incomplete evaluation standards for IT detection persist.

    Results: Massifquant is an open-source solution for KF IT detection that has been subjected to novel and rigorous methods of performance evaluation. The presented evaluation with accompanying annotations and optimization guide sets a new standard for comparative IT detection. Compared with centWave, matchedFilter and MZMine2-alternative IT detection engines-Massifquant detected more true ITs in a real LC-MS complex sample, especially low-intensity ITs. It also offers competitive specificity and equally effective quantitation accuracy.

  • 79.
    Crescenzi, C
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Albinana, J
    Carlsson, H
    Holmgren, E
    Batlle, R
    On-line strategies for determining trace levels of nitroaromatic explosives and related compounds in water2007In: J. Chromatogr. A, Vol. 1153, no 1-2, p. 186-193Article in journal (Refereed)
  • 80.
    Csenki, Leonard
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Alm, Erik
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Torgrip, Ralf J. O.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Åberg, K. Magnus
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Nord, Lars I.
    Schuppe-Koistinen, Ina
    Lindberg, Johan
    Proof of principle of a generalized fuzzy Hough transform approach to peak alignment of one-dimensional 1H NMR data2007In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 389, no 3, p. 875-885Article in journal (Refereed)
    Abstract [en]

    In metabolic profiling, multivariate data analysis techniques are used to interpret one-dimensional (1D) 1H NMR data. Multivariate data analysis techniques require that peaks are characterised by the same variables in every spectrum. This location constraint is essential for correct comparison of the intensities of several NMR spectra. However, variations in physicochemical factors can cause the locations of the peaks to shift. The location prerequisite may thus not be met, and so, to solve this problem, alignment methods have been developed. However, current state-of-the-art algorithms for data alignment cannot resolve the inherent problems encountered when analysing NMR data of biological origin, because they are unable to align peaks when the spatial order of the peaks changes—a commonly occurring phenomenon. In this paper a new algorithm is proposed, based on the Hough transform operating on an image representation of the NMR dataset that is capable of correctly aligning peaks when existing methods fail. The proposed algorithm was compared with current state-of-the-art algorithms operating on a selected plasma dataset to demonstrate its potential. A urine dataset was also processed using the algorithm as a further demonstration. The method is capable of successfully aligning the plasma data but further development is needed to address more challenging applications, for example urine data.

  • 81.
    Dahlin, Jakob
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Aerosols of Isocyanates, Amines and Anhydrides: Sampling and Analysis2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents methods for air sampling and determination of isocyanates, amines, aminoisocyanates and anhydrides. These organic compounds are generated during thermal degradation of polymers such as polyurethane (PUR) or epoxy.

    Isocyanates, amines and anhydrides are airway irritants known to cause occupational asthma. Some of the compounds are listed as human carcinogens. Many workers are exposed.

    Isocyanates and anhydrides are reactive and needs to be immediately derivatized during sampling. Methods have been developed for determination of airborne isocyanates, aminoisocyanates and anhydrides using di-n-butylamine (DBA) as reagent to form stabile urea derivatives or amide derivatives. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) enabled detection limits as low as 10 attomoles. A nitrogen-selective LC-detector enabled quantification of DBA-derivatives in reference solutions.

    A novel sampler is presented. The sampler consists of a denuder in series with a three-stage cascade impactor and an end filter. The sampler made it possible to reveal the distribution of isocyanates between gas and different particle size fractions. During thermal degradation of PUR, isocyanates were associated to particle size fractions (<1 µm) that may penetrate to the lower airways. The distribution during 8 minutes changes noticeably. Aromatic isocyanates become associated to small particles (<1 µm). As a reference method, air-sampling was performed using an impinger filled with di-n-butylamine (DBA) in toluene, connected in series with a glass fiber filter. There was a good agreement between the denuder-impactor sampler and the reference method.

  • 82.
    Dahlin, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Karlsson, Daniel
    Skarping, Gunnar
    Dalene, Marianne
    Determination of airborne anhydrides using LC-MS monitoring negative ions of di-n-butylamine derivatives2004In: Journal of Environmental Monitoring, ISSN 1464-0325, Vol. 6, no 7, p. 624-629Article in journal (Refereed)
  • 83.
    Dahlin, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Spanne, Mårten
    Dalene, Marianne
    Karlsson, Daniel
    Skarping, Gunnar
    Size-separated sampling and anlysis of isocyanates in workplace aerosols. Part II. Ageing aerosols from thermal degradation of polyurethaneManuscript (Other academic)
  • 84.
    Dahlin, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Spanne, Mårten
    Karlsson, Daniel
    Dalene, Marianne
    Skarping, Gunnar
    Size-separated sampling and anlysis of isocyanates in workplace aerosols. Part I. Denuder-cascade impactor samplerManuscript (Other academic)
  • 85.
    Daryanavard, Seyed
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Jeppsson-Dadoun, Amin
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Andersson, Lars I.
    Hashemi, Mahdi
    Colmsjö, Anders
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Molecularly imprinted polymer in microextraction by packed sorbent for the simultaneous determination of local anesthetics: lidocaine, ropivacaine, mepivacaine and bupivacaine in plasma and urine samples2013In: BMC Biomedical chromotography, ISSN 0269-3879, E-ISSN 1099-0801, Vol. 27, no 11, p. 1418-1488Article in journal (Refereed)
    Abstract [en]

    This study presents the use of molecularly imprinted polymer (MIP) as packing material for microextraction by packed syringe (MEPS) to achieve higher extraction selectivity. Pentycaine was used as template for MIP. Development and validation of the determination of lidocaine, ropivacaine, mepivacaine and bupivacaine in human plasma and urine samples utilizing MIP-MEPS and liquid chromatography–tandem mass spectrometry (LC-MS/MS) were carried out. The MEPS MIP-cartridge could be used for 100 extractions before it was discarded. The extraction recovery ranged from 60 to 80%. The correlation coefficients values were >0.999 for all assays using lidocaine, ropivacaine, mepivacaine and bupivacaine in the calibration range 5–2000 nmol/L. The accuracy of the studied compounds, given as a percentage variation from the nominal concentration values, ranged from -4.9 to 8.4% using plasma and urine samples. The between-batch precision, given as the relative standard deviation, at three different concentrations (quality control samples) was ranged from −4.7 to 14.0% and from 1.8 to 12.7% in plasma and urine, respectively. The lower limit of quantification and limit of detection of the studied substances were 5.0 and 1.0 nm, respectively

  • 86.
    Daryanavard, Seyed Mosayeb
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Microextraction by packed sorbent of drugs and peptides in biological fluids2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Sample preparation as the first step in an analytical procedure has an important role, particularly in bioanalysis, because of the complexity of biological samples (blood plasma and urine). Biological matrix such as plasma and blood contains proteins, organic and inorganic salts, acids, bases and various organic compounds with similar chemistry to the analytes of interest. Thus the basic concept of a sample preparation method is to convert a real matrix into a format that is suitable for analysis by an analytical technique. Therefore the choice of an appropriate sample preparation method greatly influences the reliability and accuracy of the analysis results.

    The aim of this thesis was to develop and validate of microextraction by packed syringe (MEPS) as a fast, selective, accurate and fully automated sample preparation technique for determination of BAM peptides in human plasma and local anaesthtics in human plasma and urine samples using silica and polymer sorbents.

    First work presents use of MEPS technique online with LC-MS/MS as a tool for the quantification of BAM peptide in plasma samples. MEPS technique provides significant advantages such as the speed and the simplicity of the sample-preparation process. Compared with other extraction techniques, such as protein precipitation and ultrafiltration, MEPS gave cleaner samples and higher recovery.

    In the second work, MEPS technique was developed by using synthesized molecularly imprinted polymer (MIP) as a sorbent for selective quantification of a homologous series of local anaesthetics, containing lidocaine, ropivacaine, mepivacaine, and bupivacaine in human plasma and urine samples. Compared with other conventional sorbent, the use of MIP provides high selectivity of the extraction and decrease the matrix effect.   

  • 87.
    Demirbüker, Mustafa
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Analysis of lipids by supercritical fluid chromatography1992Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis is described the development of new metods for the analysis of triacylglycerols and fatty acid methyl esters by supercritical fluid chromatography. Packed micro columns have been utilized for SFC and the properties of different types of packing materials have been evaluated. For evaluation, columns were thus in situ impregnated with silver ions (argentation), permanganate, periodate and triazine-based dyes. Columns packed with silica particles have also been investigated. With all these phases, it appears that the silica surface residual silanols were deactivated with regard to interaction with solute molecules when small amounts of modifiers were added to the mobile phase. For elution of unsaturated compounds on silver impregnated columns, it was necessary to add a higher content of modifiers to the mobile phase in order to achieve a partial deactivation of the double bond/silver ion complexes. It was not possible to use a flame ionization detector with such mobile phases. Therefore an ultraviolet ( UV ) detector must be utilized for the detection, even though the responses for triacylglycerols and fatty acid methyl esters were strongly dependent on the number of double bonds. Excellent separations of triacylglycerols and of fatty acid methyl esters have been obtained. Further, the columns were extremely stable from a physical as well as from a chemical point of view.

    For quantitative analysis of saturated and unsaturated triacylglycerols a miniaturized evaporative light scattering detector ( ELSD ) for connection to packed micro columns SFC has been developed. This detector could be used with pressure programming and the detection limit was lower than 6 ng.

  • 88. Douglas, T. A.
    et al.
    Tamburro, Davide
    Fredolini, C.
    Espina, B. H.
    Lepene, B. S.
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Espina, V.
    Petricoin, E. F.
    Liotta, L. A.
    Luchini, A.
    The use of hydrogel microparticles to sequester and concentrate bacterial antigens in a urine test for Lyme disease2011In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 32, no 4, p. 1157-1166Article in journal (Refereed)
    Abstract [en]

    Hydrogel biomarker capturing microparticles were evaluated as a biomaterial to amplify the sensitivity of urine testing for infectious disease proteins. Lyme disease is a bacterial infection transmitted by ticks. Early diagnosis and prompt treatment of Lyme disease reduces complications including arthritis and cardiac involvement. While a urine test is highly desirable for Lyme disease screening, this has been difficult to accomplish because the antigen is present at extremely low concentrations, below the detection limit of clinical immunoassays. N-isopropylacrylamide (NIPAm) - acrylic acid (AAc) microparticles were covalently functionalized with amine containing dyes via arnidation of carboxylic groups present in the microparticles. The dyes act as affinity baits towards protein analytes in solution. NIPAm/AAc microparticles functionalized with acid black 48 (AB48) mixed with human urine, achieved close to one hundred percent capture and 100 percent extraction yield of the target antigen. In urine, microparticles sequestered and concentrated Lyme disease antigens 100 fold, compared to the absence of microparticles, achieving an immunoassay detection sensitivity of 700 pg/mL in 10 mL urine. Antigen present in a single infected tick could be readily detected following microparticle sequestration. Hydrogel microparticles functionalized with high affinity baits can dramatically increase the sensitivity of urinary antigen tests for infectious diseases such as Lyme disease. These findings justify controlled clinical studies evaluating the sensitivity and precision of Lyme antigen testing in urine.

  • 89.
    Ekman, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Tollbäck, Petter
    Department of Analytical Chemistry.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Proteomic analysis of the cyanobacterium of the Azolla symbiosis: identity, adaptation, and NifH modification.2007In: J Exp Bot, ISSN 0022-0957Article in journal (Refereed)
  • 90.
    Ekman, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Tollbäck, Petter
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Klint, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Protein expression profiles in an endosymbiotic cyanobacterium revealed by a proteomic approach2006In: Molecular Plant-Microbe Interactions, ISSN 0894-0282, E-ISSN 1943-7706, Vol. 19, no 11, p. 1251-1261Article in journal (Refereed)
    Abstract [en]

    Molecular mechanisms behind adaptations in the cyano-bacterium (Nostoc sp.) to a life in endosymbiosis with plants are still not clarified, nor are the interactions between the partners. To get further insights, the proteome of a Nostoc strain, freshly isolated from the symbiotic gland tissue of the angiosperm Gunnera manicata Linden, was analyzed and compared with the proteome of the same strain when free-living. Extracted proteins were separated by two-dimensional gel electrophoresis and were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry combined with tandem mass spectrometry. Even when the higher percentage of differentiated cells (heterocysts) in symbiosis was compensated for, the majority of the proteins detected in the symbiotic cyanobacteria were present in the free-living counterpart, indicating that most cellular processes were common for both stages. However, differential expression profiling revealed a significant number of proteins to be down-regulated or missing in the symbiotic stage, while others were more abundant or only expressed in symbiosis. The differential protein expression was primarily connected to i) cell envelope-associated processes, including proteins involved in exopolysaccharide synthesis and surface and membrane associated proteins, ii) to changes in growth and metabolic activities (C and N), including upregulation of nitrogenase and proteins involved in the oxidative pentose phosphate pathway and downregu-lation of Calvin cycle enzymes, and iii) to the dark, micro-aerobic conditions offered inside the Gunnera gland cells, including changes in relative phycobiliprotein concentrations. This is the first comprehensive analysis of proteins in the symbiotic state.

  • 91.
    Ericson, Hanna
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Thorsen, Gunnar
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Kumblad, Linda
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Physiological effects of diclofenac, ibuprofen and propranolol on Baltic Sea blue mussels2010In: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 99, no 2, p. 223-231Article in journal (Refereed)
    Abstract [en]

    Pharmaceuticals are constantly dispersed into the environment and little is known of the effects on non-target organisms. This is an issue of growing concern. In this study, Baltic Sea blue mussels, Mytilus edulis trossulus, were exposed to diclofenac, ibuprofen and propranolol, three pharmaceuticals that are produced and sold in large quantities and have a widespread occurrence in aquatic environments. The mussels were exposed to pharmaceuticals in concentrations ranging from 1 to 10,000 mu g l(-1). The pharmaceuticals were added both separately and in combination. Mussels exposed to high concentrations of pharmaceuticals showed a clear response compared to controls. Firstly, they had a significantly lower scope for growth, which indicates that the organisms had a smaller part of their energy available for normal metabolism, and secondly, they had lower byssus strength and lower abundance of byssus threads, resulting in reduced ability to attach to the underlying substrate. Mussels exposed to lower concentrations showed tendencies of the same results. The concentration of diclofenac and propranolol was quantified in the mussels using both liquid chromatography coupled to mass spectrometry (LC-MS). The measurements showed a significantly higher concentration in the organisms as compared to the water the mussels were exposed to; the uptake reached concentrations two orders of magnitudes higher than found in sewage treatment plant effluents. This study showed that common pharmaceuticals are taken up and negatively affect the physiology of a non-target species at levels of two to three orders of magnitudes higher than found in sewage treatment plant effluents.

  • 92.
    Ericsson, Magnus
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Development of dynamic microwave and sonication-assisted extraction techniques coupled on-line to gas chromatography2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the evaluation and construction of two solvent extraction methods for solid samples. The techniques are called Dynamic microwaveassisted extraction (I-III) and Dynamic sonication-assisted solvent extraction (IV-V). Both techniques are based on dynamic solvent extraction and are performed at elevated temperatures and pressures. These characteristics enhance the extraction rates and allow solvent consumption to be reduced. In addition, due to the enhanced extraction, less hazardous extraction solvents than those used for the reference methods can be utilized. The developed techniques were validated in a comparative study with established extraction methods, such as Soxhlet, static microwave-assisted extraction and static sonication-assisted extraction. The results obtained from the presented techniques were in all cases found to be better or equal to the established reference methods in terms of extraction recovery, time and precision. The microwave-based technique was coupled to a solid phase extraction system (II). This allowed extraction, trapping and purification of analytes from complex samples such as soil and sediment to be done in a single, automated analytical procedure. Both developed methods were also connected on-line to large-volume injection gas chromatography (III, V). Thus automation of the entire laboratory procedure was achieved. The introduced methods were used for the determination of polycyclic aromatic hydrocarbons in sediment and soil (I, II) and organophosphate esters in samples of indoor air collected on glass fiber filters (III-V).

  • 93. Eriksson, A. C.
    et al.
    Nordin, E. Z.
    Nyström, R.
    Pettersson, E.
    Swietlicki, E.
    Bergvall, Christoffer
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Westerholm, Roger
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Boman, C.
    Pagels, J. H.
    Particulate PAH Emissions from Residential Biomass Combustion: Time-Resolved Analysis with Aerosol Mass Spectrometry2014In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, no 12, p. 7143-7150Article in journal (Refereed)
    Abstract [en]

    Time-resolved emissions of particulate polycyclic aromatic hydrocarbons (PAHs) and total organic particulate matter (OA) from a wood log stove and an adjusted pellet stove were investigated with high-resolution time-of-flight aerosol mass spectrometry (AMS). The highest OA emissions were found during the addition of log wood on glowing embers, that is, slow burning pyrolysis conditions. These emissions contained about 1% PAHs (of OA). The highest PAH emissions were found during fast burning under hot air starved combustion conditions, in both stoves. In the latter case, PAHs contributed up to 40% of OA, likely due to thermal degradation of other condensable species. The distribution of PAHs was also shifted toward larger molecules in these emissions. AMS signals attributed to PAHs were found at molecular weights up to 600 Da. The vacuum aerodynamic size distribution was found to be bimodal with a smaller mode (Dva ~ 200 nm) dominating under hot air starved combustion and a larger sized mode dominating under slow burning pyrolysis (Dva ~ 600 nm). Simultaneous reduction of PAHs, OA and total particulate matter from residential biomass combustion may prove to be a challenge for environmental legislation efforts as these classes of emissions are elevated at different combustion conditions.

  • 94. Eriksson, Annika K.
    et al.
    Tran, Thuy
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Saxin, S
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Effects of A-site substitution on the structure and magnetic properties of Bi0.15Sr0.85-yAeyCo1-xFexO3-? perovskites2009In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 11, no 11, p. 1945-1954Article in journal (Refereed)
    Abstract [en]

    The effects of partial substitution of Sr2+ by Ca2+ and Ba2+ on the A-site of oxygen deficient perovskites, Bi0.15Sr0.85-yAeyCo1-xFexO3-?, where y = 0.29 for Ae = Ba and y = 0.17 for Ae =  Ca, and 0.0 ? x ? 1.0, have been investigated. The differing ionic size of the Ca2+ and Ba2+ cations influences both the crystal structure and the properties of the materials. The smaller Ca2+ cation favoured formation of an oxygen vacancy ordered perovskite superstructure (I4/mmm, a = 2ap, c = 4ap), meanwhile the presence of the larger Ba2+ cation promoted a disordered simple cubic structure (Pm-3m, a = ap) that was also found for all Fe containing samples, i.e. x ? 0.25. The samples were studied with PXRD, NPD, TGA, HREM and magnetic susceptibility measurements. All as-prepared samples exhibited long range G-type antiferromagnetic ordering. The effect of oxygen annealing was dramatic for the Bi0.15Sr0.68Ca0.17Co1-xFexO3-? series with a disappearance of magnetic order for x ? 0.25 linked to increasing spin glass properties. The oxygen content of the Bi0.15Sr0.56Ba0.29Co1-xFexO3-? as-prepared materials was generally higher than their Ca substituted counterparts, and the long range antiferromagnetic order was more resistant to oxygen annealing.

  • 95.
    Eriksson Wiklund, Ann-Kristin
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Oskarsson, Hanna
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Thorsen, Gunnar
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Kumblad, Linda
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Behavioural and physiological responses to pharmaceutical exposure in macroalgae and grazers from a Baltic Sea littoral community2011In: Aquatic Biology, ISSN 1864-7782, E-ISSN 1864-7790, Vol. 14, no 1, p. 29-39Article in journal (Refereed)
    Abstract [en]

    Gammarus spp. and Fucus vesiculosus from the Baltic Sea littoral community were exposed to 3 concentrations of the pharmaceuticals ibuprofen and propranolol. Both physiological and behavioural parameters were measured to examine potential effects in the organisms. For Gammarus spp., respiration, feeding rate and activity with and without predator cues were measured, and gross production to respiration ratio (GP/R) and chlorophyll fluorescence were measured for F. vesiculosus. The results showed that propranolol decreased the activity related to movement, and Gammarus spp. could not compensate for the reduced movement when subjected to predator cues. The feeding rates of Gammarus spp. exposed to propranolol were more than 2 times higher at all concentrations compared to the control. Ibuprofen did not significantly affect any of the measured parameters of Gammarus spp. The GP/R was lower in algae exposed to propranolol. The effects of propranolol on both behaviour and physiology of Gammarus spp., in combination with the stress responses in the algae, might cause unexpected indirect and cascade effects which eventually could have implications at both community and ecosystem scales.

  • 96. Forshed, J
    et al.
    Stolt, R
    Idborg, H
    Jacobsson, S.P
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Enhanced multivarate analysis by correlation scaling and fusion of LC/MS and 1HNMR data2007In: CHEMOM. INTELL. LAB. SYST, Vol. 85, p. 179-185Article in journal (Refereed)
  • 97.
    Forshed, Jenny
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Processing and analysis of NMR data: Impurity determination and metabolic profiling2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the use of nuclear magnetic resonance (NMR) spectrometry as an analytical tool. The theory of NMR spectroscopy in general and quantitative NMR spectrometry (qNMR) in particular is described and the instrumental properties and parameter setups for qNMR measurements are discussed. Examples of qNMR are presented by impurity determination of pharmaceutical compounds and analysis of urine samples from rats fed with either water or a drug (metabolic profiling). The instrumental parameter setup of qNMR and traditional data pre-treatments are examined. Spectral smoothing by convolution with a triangular function, which is an unusual application in this context, was shown to be successful regarding the sensitivity and robustness of the method in paper II. In addition, papers III and IV comprise the field of peak alignment, especially designed for 1H-NMR spectra of urine samples. This is an important preprocessing tool when multivariate analysis is to be applied. A novel peak alignment method was developed and compared to the traditional bucketing approach and a conceptually different alignment method.

    Univariate, multivariate, linear and nonlinear data analyses were applied to qNMR data. In papers I–II, calibration models were created to examine the potential of qNMR for these applications. The data analysis in papers III–VI was mainly explorative. The potential of data fusion and data correlation was examined in order to increase the possibilities of analysing the highly complex samples from metabolic profiling (papers V–VI). Data from LC/MS analysis of the same samples were used with the 1H-NMR data in different ways. Correlation analyses between the 1H-NMR data and the drug metabolites identified from the LC/MS data were also performed. In this process, data fusion proved to be a valuable tool.

  • 98.
    Forshed, Jenny
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Andersson, Fredrik O.
    Jacobsson, Sven P.
    NMR and Bayesian regularized neural network regression for impurity determination of 4-aminophenol2002In: Journal of Pharmaceutical and Biomedical Analysis, ISSN 0731-7085, Vol. 29, no 3, p. 495-505Article in journal (Refereed)
  • 99.
    Forshed, Jenny
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Erlandsson, Bengt
    Jacobsson, Sven P.
    Quantification of aldehyde impurities in poloxamer by 1H NMR spectrometry2005In: Analytica Chimica Acta, ISSN 0003-2670, Vol. 552, no 1-2, p. 160-165Article in journal (Refereed)
  • 100. Forshed, Jenny
    et al.
    Idborg, Helena
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Jacobsson, Sven P
    Evaluation of different techniques for data fusion of LC/MS and 1H-NMR2007In: Chemometrics and Intelligent Laboratory Systems, ISSN 0169-7439, Vol. 85, no 1, p. 102-109Article in journal (Refereed)
1234567 51 - 100 of 370
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