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  • 1.
    Ali, Tara
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Essén, Sofia A.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Lundström, Ulla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Liquid extraction of low molecular mass organic acids and hydroxamate siderophores from boreal forest soil2011Inngår i: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 43, nr 12, s. 2417-2422Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low molecular mass organic acids (LMMOAs) and hydroxamate siderophores (HS) are molecules secreted by microbes and have previously been found in soil solution and in cultures. Mycorrhizal fungi are suggested to be involved in the nutrient uptake processes of trees and weathering of minerals. In this study soil samples taken from the O and E horizons of a podzol were extracted with 10 mM potassium phosphate buffer at pH 7.2. Variable parameters included addition of methanol to the extraction buffer and the use of ultrasonication or rotary shaking during extraction. LMMOAs and HS content of the soil extracts were determined. Analysis of soil extracts were carried out by liquid chromatography mass spectrometry (LC-MS) and the extraction results compared to results for soil solution samples obtained by centrifugation of the soils sampled. The extraction yields were significantly increased by addition of methanol to the extraction buffer, especially for the O horizon samples. Rotary shaking of the samples for 90 min gave slightly higher yields than ultrasonication for 15 min but the reduction in extraction time makes ultrasonication an attractive option. Of the HSs determined, ferricrocin was found in all samples. Optimal extraction conditions showed citric acid and isocitric acid to be the most abundant organic acids in the O and E horizons, respectively.

  • 2.
    Boija, Susanne
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Almesåker, Ann
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Determination of conditional stability constants for some divalent transition metal ion-EDTA complexes by electrospray ionization mass spectrometry2014Inngår i: Journal of Mass Spectrometry, ISSN 1076-5174, E-ISSN 1096-9888, Vol. 49, nr 7, s. 550-556Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Conditional stability constants of coordination complexes comprising divalent transition metals, Cu2+, Ni2+, Zn2+, Co2+, and ethylenediaminetetraacetic acid (EDTA) were determined utilizing electrospray ionization mass spectrometry. The deviation of signal response of a reference complex was monitored at addition of a second metal ion. The conditional stability constant for the competing metal was then determined through solution equilibria equations. The method showed to be applicable to a system where Co2+ and Zn2+ competed for EDTA at pH 5. When Cu2+ and Ni2+ competed for EDTA, the equilibrium changed over time. This change was shown to be affected in rate and size by the type of organic solvent added. In this work, 30% of either methanol or acetonitrile was used. It was found that if calibration curves are prepared for both metal complexes in solution and the measurements are repeated with sufficient time space, any change in equilibrium of sample solutions will be discovered. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

  • 3.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Chemometric tools for enhanced performance in liquid chromatography-mass spectrometry2001Doktoravhandling, monografi (Annet vitenskapelig)
  • 4.
    Bylund, Dan
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bergens, Arne
    Jacobsson, S P.
    Optimisation of chromatographic separations by use of a chromatographic response function, empirical modelling and multivariate analysis1997Inngår i: Chromatographia, ISSN 0009-5893, Vol. 44, nr 1/2, s. 74-80Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chiral separation of the drug substance R,S-oxybutynin chloride on a reversed phase HPLC system has been optimised by use of empirical modelling and multivariate analysis. The separation was characterised by a new chromatographic response function developed to modulate both quality of separation and retention time. The study includes a comparison between three different multivariate techniques (multi-layer feed-forward neural networks, multiple linear regression and partial least squares regression) of their capabilities to model the new chromatographic response function and predict its value for new experiments. It was indicated that the most accurate models were achieved with neural networks, although partial least squares regression could also be used to solve the problem since it gives the major directions for the optimal settings of the variables.

  • 5.
    Bylund, Dan
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Danielsson, Rolf
    Malmquist, Gunnar
    Markides, Karin A
    Chromatographic alignment by warping and dynamic programming as a pre-processing tool for PARAFAC modelling of liquid chromatography-mass spectrometry data2002Inngår i: Journal of Chromatography A, ISSN 0021-9673, Vol. 961, nr 2, s. 237-244Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solutes analysed with LC–MS are characterised by their retention times and mass spectra, and quantified by the intensities measured. This highly selective information can be extracted by multiway modelling. However, for full use and interpretability it is necessary that the assumptions made for the model are valid. For PARAFAC modelling, the assumption is a trilinear data structure. With LC–MS, several factors, e.g. non-linear detector response and ionisation suppression may introduce deviations from trilinearity. The single largest problem, however, is the retention time shifts not related to the true sample variations. In this paper, a time warping algorithm for alignment of LC–MS data in the chromatographic direction has been examined. Several refinements have been implemented and the features are demonstrated for both simulated and real data. With moderate time shifts present in the data, pre-processing with this algorithm yields approximately trilinear data for which reasonable models can be made.

  • 6.
    Bylund, Dan
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Danielsson, Rolf
    Markides, Karin E
    Peak purity assessment in liquid chromatography-mass spectrometry2001Inngår i: Journal of Chromatography A,, ISSN 0021-9673, Vol. 915, nr 1/2, s. 43-52Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fixed-size moving window evolving factor analysis and base peak chromatograms have been used for peak purity detection in data generated with LC–MS. The two methods were evaluated with both real and simulated data and were found to be fast and complementary to each other. When a possibly impure peak is detected, it is suggested that further information can be obtained from local principal component analysis modelling and comparative mass chromatogram plots.

  • 7.
    Bylund, Dan
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Henriksson, Anders E.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap. Sundsvalls sjukhus.
    Proteomic approaches to identify circulating biomarkers in patients with abdominal aortic aneurysm2015Inngår i: American Journal of Cardiovascular Disease, ISSN 2160-200X, Vol. 5, nr 3, s. 140-145Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Abdominal aortic aneurysm (AAA) is a common condition with high mortality when ruptured. Most clinicians agree that small AAAs are best managed by ultrasonographic surveillance. However, it has been stated in recent reviews that a serum/plasma biomarker that predicts AAA rupture risk would be a powerful tool in stratifying patients with small AAAs. Identification of such circulating biomarkers with traditional hypothesis driven studies has been unsuccessful. In this review we summarize six studies using different proteomic approaches to find new, potential plasma AAA biomarker candidates. In conclusion, by using proteomic approaches novel potential plasma biomarkers for AAA have been identified.

  • 8.
    Bylund, Dan
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Norström, Sara
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Essén, Sofia
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Lundström, Ulla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Analysis of low molecular mass organic acids in natural waters by ion exclusion chromatography tandem mass spectrometry2007Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1176, nr 1-2, s. 89-93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A sensitive and selective method for the analysis of aliphatic low molecular mass organic acids (LMMOAs) in natural waters is presented. The method is based on separation with ion exclusion chromatography and detection with electrospray ionization tandem mass spectrometry (LC-MS/MS). The extra selectivity gained by applying MS/MS allows for a minimum of sample preparation and the use of a sub-optimal mobile phase regarding chromatographic resolution. Instead the mobile phase, comprising aqueous formic acid With methanol as organic modifier, was mainly optimized for maximum sensitivity and long term MS stability. Detection limits for malonic, fumaric, maleic, succinic, citraconic, glutaric, malic, alpha-ketoglutaric, tartaric, shikimic, trans-aconitic, cis-aconitic, isocitric and citric acid were in the range 1-50 nM, while the detection limits for pyruvic, oxalic and lactic acid were around 250 nM for an injection volume of 100 mu L. Due to their metal-chelating properties, these LMMOAs are all considered to affect the bioavailability of metals and to be involved in soil forming processes. It is thus of interest to be able to monitor their presence in natural waters, and the method developed within this work was successfully applied for the analysis of LMMOAs in soil solution and stream water samples.

  • 9.
    Bylund, Dan
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Samskog, J
    Jacobsson, S.P.
    Markides, K.E.
    Classification of lactate dehydrogenase of different origin by liquid chromatography-mass spectrometry and multivariate analysis2003Inngår i: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 14, nr 3, s. 236-240Artikkel i tidsskrift (Fagfellevurdert)
  • 10.
    Bökman, C.F.
    et al.
    Clinical Chemistry Laboratory, Falun Central Hospital, Falun.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Markides, K.E.
    Department of Analytical Chemistry, Uppsala University, Uppsala.
    Sjöberg, P.J.R.
    Department of Analytical Chemistry, Uppsala University, Uppsala .
    Relating chromatographic retention and electrophoretic mobility to the ion distribution within electrosprayed droplets2006Inngår i: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 17, nr 3, s. 318-324Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ions that are observed in a mass spectrum obtained with electrospray mass spectrometry can be assumed to originate preferentially from ions that have a high distribution to the surface of the charged droplets. In this study, a relation between chromatographic retention and electrophoretic mobility to the ion distribution (derived from measured signal intensities in mass spectra and electrospray current) within electrosprayed droplets for a series of tetraalkylammonium ions, ranging from tetramethyl to tetrapentyl, is presented. Chromatographic retention in a reversed-phase system was taken as a measure of the analyte's surface activity, which was found to have a large influence on the ion distribution within electrosprayed droplets. In addition, different transport mechanisms such as electrophoretic migration and diffusion can influence the surface partitioning coefficient. The viscosity of the solvent system is affected by the methanol content and will influence both diffusion and ion mobility. However, as diffusion and ion mobility are proportional to each other, we have, in this study, chosen to focus on the ion mobility parameter. It was found that the influence of ion mobility relative to surface activity on the droplet surface partitioning of analyte ions decreases with increasing methanol content. This effect is most probably coupled to the decrease in droplet size caused by the decreased surface tension at increasing methanol content. The same observation was made upon increasing the ionic strength of the solvent system, which is also known to give rise to a decreased initial droplet size. The observed effect of ionic strength on the droplet surface partitioning of analyte ions could also be explained by the fact that at higher ionic strength, a larger number of ions are initially closer to the droplet surface and, thus, the contribution of ionic transport from the bulk liquid to the liquid/air surface interface (jet and droplet surface), attributable to migration or diffusion will decrease.

  • 11. Danielsson, Rolf
    et al.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Markides, Karin E
    Matched filtering with background suppression for improved quality of base peak chromatograms and mass spectra in liquid chromatography-mass spectrometry2002Inngår i: Analytica Chimica Acta, ISSN 0003-2670, Vol. 454, nr 2, s. 167-184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A time domain filter that combines the properties of matched filtering and two-fold differentiation is presented. The filter coefficients are given by the second derivative of a Gaussian model peak, controlled by the setting of two parameters related to the chromatographic system. The fundamental characteristics of the filter were derived, and its applicability demonstrated for real liquid chromatography–mass spectrometry (LC–MS) data. The filter is primarily intended as a fast pre-processing step, for a mass chromatogram with 320 scans over 700 mass channels the computation time was 0.6 s on a standard PC. Base peak chromatograms with improved peak detection capability and mass spectra useful for compound identification were obtained with filtered data. The most significant effect of the described filter is background reduction due to the differentiation, which in combination with the matched filter can be performed with maintained or even improved signal-to-noise ratio.

  • 12.
    Essén, Sofia
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Holmström, Sara
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Moberg, M
    Uppsala University.
    Lundström, Ulla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Quantification of hydroxamate siderophores in soil solutions of podzolic soil profiles in Sweden2006Inngår i: Biometals, ISSN 0966-0844, E-ISSN 1572-8773, Vol. 19, nr 3, s. 269-282Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Concentrations up to 2 and 12 nM of the hydroxamate siderophores ferrichrome and ferricrocin, respectively, were identified in soil solutions of podzolic forest soils at four sites in both northern and southern Sweden. No ferrichrysin was detected. As with the dissolved organic carbon and low molecular mass organic acids, the highest concentrations of the siderophores were found in the upper layers i.e. the mor layer, the eluvial and upper illuvial horizons. At the southern sites, the concentrations of ferrichrome and ferricrocin were both of similar magnitude and did not differ between the two sites. In contrast, soil solutions at the two northern sites contained more ferricrocin than ferrichrome; the ferricrocin concentrations were also higher at the northern sites than at the southern sites. Analyses were performed by high performance liquid chromatography with a porous graphitic carbon column on which ferrichrome, ferricrocin and ferrichrysin were separated. Detection by electrospray ionization mass spectrometry (ESI-MS) combined with on-line sample pre-concentration, by means of column-switching, enabled detection limits of 0.1-0.2 nM for ferrichrome, ferrichrysin and ferricrocin. The structural identities of the siderophores were further verified by MS/MS fragmentation. Fragmentation of ferrichrome, ferricrocin and ferrichrysin occured mainly via peptide cleavage. The most intense fragments were typified by the loss of one of the three iron(III) chelating hydroxamate residues, i.e N5-acyl-N5-hydroxy ornithine.

  • 13.
    Essén, Sofia
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Walve, J
    Ingri, J
    Lundström, Ulla S
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Quantification of hydroxamate siderophores in the Baltic Sea and cyanobacterial populations by capillary LC-ESI-MS/MSManuskript (Annet (populærvitenskap, debatt, mm))
  • 14.
    Essén, Sofia
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Johnson, Anna
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Pedersen, Karsten
    Lundström, Ulla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Siderophore production by Pseudomonas stutzeri under aerobic and anaerobic conditions2007Inngår i: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 73, nr 18, s. 5857-5864Artikkel i tidsskrift (Fagfellevurdert)
  • 15. Forsgard, N.
    et al.
    Sjöberg, P.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Andersson, M.
    Pettersson, J.
    Screening and identification of aluminium-containing biomolecules by column-switched LC-ICP-MS and LC-ESI-MS/MS2007Inngår i: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 22, nr 11, s. 1397-1402Artikkel i tidsskrift (Fagfellevurdert)
  • 16.
    Fransson, Petra
    et al.
    Swedish Univ Agr Sci, Uppsala BioCtr, Dept Forest Mycol & Plant Pathol, Uppsala, Sweden.
    Andersson, Alexandra
    Swedish Univ Agr Sci, Uppsala BioCtr, Dept Forest Mycol & Plant Pathol, Uppsala, Sweden.
    Norström, Sara
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap. Umeå Univ, Dept Chem, SE-90187 Umeå, Sweden.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Bent, Elizabeth
    Univ Guelph, Sch Environm Sci, Guelph, ON N1G 2W1, Canada.
    Ectomycorrhizal exudates and pre-exposure to elevated CO2 affects soil bacterial growth and community structure2016Inngår i: Fungal ecology, ISSN 1754-5048, E-ISSN 1878-0083, Vol. 20, s. 211-224Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ectomycorrhizal fungi produce low molecular weight organic compounds, supporting diverse microbial communities. To link mycorrhizal root exudation directly to bacterial responses, we used Scots pine exudates with (Suillus variegatus and Piloderma fallax) and without mycorrhiza as substrata for forest soil bacteria. Bacterial growth and vitality was monitored, and community composition determined using TRFLP, cloning and sequencing. We investigated if the amount of organic acids in exudates explained bacterial growth, and whether bacterial communities were influenced by pre-exposure to elevated atmospheric CO2. We demonstrated functional differences in bacterial growth rates related to CO2. There was a shift in the bacterial community (e.g. Burkholderia sp. and gamma-proteobacteria) toward organisms better able to rapidly utilize exudates when pine microcosms were pre-exposed to elevated CO2. Soil bacteria from all treatments tended to grow more abundantly and rapidly in exudates from Pilo derma -colonized seedlings, suggesting that the organic acids and/or unidentified compounds present supported greater growth.

  • 17.
    Fredriksson, Mattias
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Petersson, Patrik
    AstraZeneca.
    Axelsson, Bengt-Olof
    AstraZeneca.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    A component tracking algorithm for accelerated and improved liquid chromatography-mass spectrometry method development2010Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1217, nr 52, s. 8195-8204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method for tracking of sample components during liquid chromatography–mass spectrometry (LC–MS) method development has been proposed. The method manages to, fully automatically and without user intervention, find the chromatographic peaks in the data sets, discriminate them to sample components and track them when the separation conditions have been changed. The algorithm utilises the resolution obtained from all considered data sets and has the ability to discriminate the non informative parts. The technique has a great sensitivity even in cases where a majority of the tracked components cannot easily be spotted by means of traditional total ion chromatogram (TIC) or base peak chromatogram (BPC) representations. The method was tested on an experimental sample using six different columns and an average of 79% of the suggested sample components could be successfully tracked at a minimum area of 0.05% of the main component in the sample. 66 components with 79–92% of the total suggested component area were able to be tracked between all data sets. The method could be used to rapidly investigate selectivity during different types of separation conditions.

  • 18.
    Fredriksson, Mattias
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Petersson, Patrik
    Axelsson, Bengt-Olof
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    An automatic peak finding method for LC-MS data using Gaussian second derivative filtering2009Inngår i: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 32, nr 22, s. 3906-3918Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly automated procedure for localising and characterising peaks in the chromatographic time domain of LC-MS data has been developed. The work was initiated by an identified need to facilitate the detection and tracking of chromatographic peaks during method development for the analysis of impurities in pharmaceutical products. The algorithm is mainly based on a digital filter for which the settings are automatically adapted to the data set under study. The procedure was evaluated for synthetic data sets with various S/N levels, peak widths and baseline properties. It was found that even for the worst case tested with S/N=10 and a high variability in the baseline, 94% of the simulated analytical peaks could be detected without producing any false-positive identifications. Furthermore, the number of correctly estimated peak heights and peak widths falling within a 10% error of the true values were 94 and 91%, respectively. For experimental data sets, peak height, and width estimations were more difficult, but the processed reconstructions showed an excellent agreement with the analytical signals of the raw data, and also a clearly improved visualisation in total ion- and base-peak chromatograms.

  • 19.
    Fredriksson, Mattias
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Petersson, Patrik
    Astra Zeneca R and D Lund, SE-221 87 Lund, Sweden.
    Axelsson, Bengt-Olof
    Astra Zeneca R and D Lund, SE-221 87 Lund, Sweden.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Combined use of algorithms for peak picking, peak tracking and retention modelling to optimize the chromatographic conditions for liquid chromatography-mass spectrometry analysis of fluocinolone acetonide and its degradation products2011Inngår i: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 704, nr 1-2, s. 180-188Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A strategy for rapid optimization of liquid chromatography column temperature and gradient shape is presented. The optimization as such is based on the well established retention and peak width models implemented in software like e.g. DryLab and LC simulator. The novel part of the strategy is a highly automated processing algorithm for detection and tracking of chromatographic peaks in noisy liquid chromatography-mass spectrometry (LC-MS) data. The strategy is presented and visualized by the optimization of the separation of two degradants present in ultraviolet (UV) exposed fluocinolone acetonide. It should be stressed, however, that it can be utilized for LC-MS analysis of any sample and application where several runs are conducted on the same sample. In the application presented, 30 components that were difficult or impossible to detect in the UV data could be automatically detected and tracked in the MS data by using the proposed strategy. The number of correctly tracked components was above 95%. Using the parameters from the reconstructed data sets to the model gave good agreement between predicted and observed retention times at optimal conditions. The area of the smallest tracked component was estimated to 0.08% compared to the main component, a level relevant for the characterization of impurities in the pharmaceutical industry.

  • 20.
    Fredriksson, Mattias
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Petersson, Patrik
    Jörntén-Karlsson, Magnus
    Axelsson, Bengt-Olof
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    An objective comparison of pre-processing methods for enhancement of liquid chromatography-mass spectrometry data2007Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1172, nr 2, s. 135-150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Four data pre-processing methods have been applied with different settings to data sets obtained from the analysis of a pharmaceutical drug and its degradation products by liquid chromatography�mass spectrometry (LC�MS). The methods compared were the frequently used component detection algorithm (CODA) and three kinds of digital filters�matched filtration (MF), Gaussian second derivative (GSD) and Savitzky�Golay. The aim was to evaluate the performance and robustness of these methods for extracted ion chromatogram (XIC), total ion chromatogram (TIC) and base peak chromatogram (BPC) in the presence of different types of noise. In accordance with theory, the best improvements in signal-to-noise ratio (S/N) of the XICs were obtained with MF under the ideal case with random white noise. However, when highly coloured noise was present, it was found that no improvements in XIC S/N could be obtained with any of the pre-processing methods studied. GSD and CODA did, however, improve the S/N for both TIC and BPC. GSD and CODA also significantly reduced the background in the spectral domain, thereby facilitating the interpretation of the mass spectra. Another advantage associated with CODA and to some extent also with GSD is their data reduction ability.

  • 21.
    Henriksson, Anders E.
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap. Sundsvall County Hospital, Sundsvall.
    Lindqvist, Markus
    Sundsvall County Hospital, Sundsvall.
    Sihlbom, Carina
    University of Gothenburg, Gothenburg.
    Bergström, J.
    University of Gothenburg, Gothenburg.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Identification of potential plasma biomarkers for abdominal aortic aneurysm using tandem mass tag quantitative proteomics2018Inngår i: Proteomes, ISSN 2227-7382, Vol. 6, nr 4, artikkel-id 43Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Plasma biomarkers that identify abdominal aortic aneurysm (AAA) rupture risk would greatly assist in stratifying patients with small aneurysms. Identification of such biomarkers has hitherto been unsuccessful over a range of studies using different methods. The present study used an alternative proteomic approach to find new, potential plasma AAA biomarker candidates. Pre-fractionated plasma samples from twelve patients with AAA and eight matched controls without aneurysm were analyzed by mass spectrometry applying a tandem mass tag (TMT) technique. Eight proteins were differentially regulated in patients compared to controls, including decreased levels of the enzyme bleomycin hydrolase. The down-regulation of this enzyme was confirmed in an extended validation study using an enzyme-linked immunosorbent assay (ELISA). The TMT-based proteomic approach thus identified novel potential plasma biomarkers for AAA. 

  • 22. Isaac, Giorgis
    et al.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Månsson, Jan Eric
    Markides, Karin E
    Bergquist, Jonas
    Analysis of phosphatidylcholine and sphingomyelin molecular species from brain extracts using capillary liquid chromatography electrospray ionization mass spectrometry2003Inngår i: Journal of Neuroscience Methods, ISSN 0165-0270, Vol. 128, nr 1/2, s. 111-119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One feature of complex lipids is that many subtypes of these molecules exist as a diverse mixture in a biological sample. Qualitative and quantitative analysis of these closely related molecules require sensitive and specific analytical methods to detect intact phospholipids (PL) and sphingomyelin (SM) species and to differentiate between them. Conventional analytical methods require laborious procedures including separation by column, argentation thin-layer chromatography or liquid chromatography (LC) after pre- or post-column derivatization. In the present work, a method based on reversed phase capillary LC coupled on-line to electrospray ionization mass spectrometry (LC/ESI/MS) has been developed to gather tools for lipidomic studies, i.e. the profiling of complex mixtures of lipids in small amounts of various cells and tissues. The LC/MS system used consisted of an LC pump in an isocratic elution, a reversed phase capillary column and a single quadrupole mass spectrometer operated in the positive ion mode. A successful separation of phosphatidylcholine (PC) and SM molecular species was obtained with a minimum detectable quantity (MDQ) in the low fmol range injected on column. The method was applied to human brain extracts. Furthermore, the extraction efficiencies of the traditional Folch method and pressurized fluid extraction (PFE) were compared using the human brain. It was found that the intensity of the PC and SM molecular species extracted by PFE is two times that of Folch.

  • 23.
    Laurén, Ari
    et al.
    Joensuu Unit, Finnish Forest Research Institute, P.O. Box 68, Joensuu 80101, Finland.
    Lappalainen, Mari
    Joensuu Unit, Finnish Forest Research Institute, P.O. Box 68, Joensuu 80101, Finland.
    Saari, Paivi
    Joensuu Unit, Finnish Forest Research Institute, P.O. Box 68, Joensuu 80101, Finland.
    Kukkonen, Jussi V. K.
    Department of Biology, University of Eastern Finland, P.O. Box 111, Joensuu 80101, Finland.
    Koivusalo, Harri
    Department of Civil and Environmental Engineering, Aalto University School of Engineering, P.O. Box 15200, Aalto 00076, Finland.
    Piirainen, Sirpa
    Joensuu Unit, Finnish Forest Research Institute, P.O. Box 68, Joensuu 80101, Finland.
    Setälä, Heikki
    Department of Environmental Sciences, University of Helsinki, Niemenkatu 73, Lahti 15140, Finland.
    Sarjala, Tytti
    Parkano Unit, Finnish Forest Research Institute, Kaironiementie 15, Parkano 39700, Finland.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Heinonen, Jaakko
    Joensuu Unit, Finnish Forest Research Institute, P.O. Box 68, Joensuu 80101, Finland.
    Nieminen, Mika
    Vantaa Unit, Finnish Forest Research Institute, P.O. Box 18, Vantaa 01301, Finland.
    Palviainen, Marjo
    Department of Forest Sciences, University of Helsinki, P.O. Box 27, Helsinki 00014, Finland.
    Launiainen, Samuli
    Joensuu Unit, Finnish Forest Research Institute, P.O. Box 68, Joensuu 80101, Finland.
    Finér, Leena
    Joensuu Unit, Finnish Forest Research Institute, P.O. Box 68, Joensuu 80101, Finland.
    Nitrogen and Carbon Dynamics and the Role of Enchytraeid Worms in Decomposition of L, F and H Layers of Boreal Mor2012Inngår i: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 223, nr 7, s. 3701-3719Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Decomposition of organic material releases carbon dioxide (CO2) into the atmosphere, and dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and ammonium (NH4-N) into soil water. Each of the decomposition products contributes differently to overall export of carbon (C) and nitrogen (N) to water courses. Our aim was to study the quantity and composition of the released C and N as affected by the organic material and soil fauna, represented by enchytraeid worms. We measured the release rate of carbon dioxide, and calculated the release rates for DOC and dissolved N in soil from repeated measurements of DOC and N pools during laboratory incubation of litter (L), fermented (F) and humus (H) layers of boreal forest mor. The intermediate decomposition products, DOC and DON, were characterised according to the molecule size. The release rate of the decomposition products was higher for fresh than for old organic material. The majority of N and C were released as NH4-N and CO2, respectively. The amount of extractable organic N in soil decreased by time but DON increased. Enchytraeids stimulated N mineralisation and the release of large molecule size DOC, particularly in L layer. The results suggest that organic N in extractable form biodegrades effectively, and that soil fauna have an important role in the decomposition. The results were interpreted from the water quality point of view and the implications of the results to modelling of decomposition and export of DOC and dissolved N to recipient water bodies are discussed. In the modelling context, the novelty of the study is the description of the intermediate decomposition products and the division of the dissolved organic compounds into low molecular weight and high molecular weight fractions.

  • 24.
    Ljunggren, Joel
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Jonsson, Bengt Gunnar
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Combinatorial Retention-Activity Relationship of Fractionated Turpentine on Fungal GrowthManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Essential oils from plants are often used in growth inhibition assays against bacteria, fungi, insects and viral infections. Turpentine from Norway spruce (Picea abies) is an essential oil produced in large quantities as a waste product in paper production. It is a complex mixture of secondary metabolites that is rich in terpenes and terpenoids. These compounds protect the tree from fungal and bacterial infection; turpentine should therefore be a good source for biologically active substances for inhibiting fungal growth. In this study, a combination of a reductive and a holistic approach was employed to find the most inhibiting compound; an approach that we have called an intermistic approach. The most inhibiting compounds was determined in three steps against growth of the saproxylic fungus Coniophora puteana: rejecting half of the turpentine search space in a reductive manner, finding the optimal concentration and finally combining fractions of the most active half of turpentine in a quadratic D-optimal design to investigate it holistically. Multivariate data analysis of gas chromatography coupled with mass spectrometry (GC-MS) chromatograms was used to zoom in on the most active compounds responsible for antifungal activity. The growth rate of C. puteana in mm/day was used as y-variable and the relative area percentage of 36 GC-MS peaks from the mixtures was used as x-variables to construct a partial least squares (PLS) regression model. The final model was reduced to 12 peaks and used to find the most promising antifungal compound within the mixture. In addition, an external validation was performed with preparatory GC on the most active fraction. From the model, one putative sesquiterpene was identified along with at least two other sesquiterpenes and one diterpene warrant further investigation. Herein, a general method for finding biologically active compounds against wood-rotting fungi, and potentially other organisms from a complex mixture, is proposed.

  • 25.
    Ljunggren, Joel
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Jonsson, Bengt-Gunnar
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Edman, Mattias
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Antifungal efficiency of individual compounds and evaluation of non-linear effects by recombining fractionated turpentine2020Inngår i: Microchemical journal (Print), ISSN 0026-265X, E-ISSN 1095-9149, Vol. 153, artikkel-id 104325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A combination between a reductive and a holistic assay was employed to investigate whole fraction, synergistic, antagonistic and individual compound efficacy of vacuumdistilled turpentine fractions against the economically important brown-rot fungus Coniophora puteana. The fungus was subjected to recombinations of turpentine fractions at a concentration of 1000 ppm. All combinations exhibited useful antifungal properties, but some antifungal mixtures showed a more pronounced effect than the expected level of inhibition. Synergistic effects by a two-fold factor and minor antagonistic effects were observed. Complete growth inhibition of C. puteana was observed by a fraction obtained after distilling 1 L turpentine at 111–177°C (0.5 mbar) as well as by mixing it with another fraction withdrawn at 70–79°C (0.5 mbar). Chemical compositions of distilled fractions were determined through GC–MS analysis and Orthogonal Partial Least Squares (OPLS) multivariate data analysis of GC–MS chromatograms was employed to zoom in on the most active compounds responsible for antifungal activity. Isomers of epicubenol, the hydrocarbon aromatic compound ar-himachalene and α-cadinol are suggested as effective antifungal compounds. In addition, a subsequent fractionation of the most effective fraction was performed with preparatory gas chromatography and subfractions showed similar or better efficacy than previously observed. Our work demonstrates the possibility to retain adequate synergistic antifungal efficiency and offers an opportunity to explore the effects of individual compounds originating from the same crude sample.

  • 26.
    Ljunggren, Joel
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Vilches, Ana Paola
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Jonsson, Bengt-Gunnar
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Changes in Extracellular Amino Acids, pH and Growth when Fungi Interact at the Near-contact Level: Heterobasidion parviporum vs. Gloeophyllum sepiariumManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Heterobasidion parviporum and Gloeophyllum sepiarium are fungal species representing two different ecological niches. H. parviporum is a parasitic white-rot fungus and early colonizer of felled wood, while the brown-rot fungus G. sepiarium is an early-middle colonizer in the natural fungi succession order. In this study, we quantitatively examined the utilization of amino acids in the μM range, pH and final dry weight from common liquid glucose-malt extract medium when the two fungi were interacting at the near-contact level. An increase in glutamine concentration was observed, and lysine was utilized in a greater extent when fungi were interacting compared to when they grew on their own. Our results also show fungal interaction is a process with high variability both in pH, growth and amino acid utilization, depending on the type of interaction. A connection between the growth, according to dry weight, and pH is suggested in the interaction between H. parviporum and G. sepiarium.

  • 27.
    Lundström, Ulla S
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Norström, Sara H
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Vestin, Jenny L K
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Essén, Sofia A
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Dissolved Organic Matter Dynamics of Soil and Stream Water in a Catchment Area, Keynote speaker2006Konferansepaper (Annet vitenskapelig)
  • 28.
    Moberg, My
    et al.
    Uppsala University.
    Bergquist, Jonas
    Uppsala University.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    A generic stepwise optimization strategy for liquid chromatography electrospray ionization tandem mass spectrometry methods2006Inngår i: Journal of Mass Spectrometry, ISSN 1076-5174, E-ISSN 1096-9888, Vol. 41, nr 10, s. 1334-1345Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The feasibility and advantages of using sophisticated chemometric tools in combination with the execution of thoroughly planned experiments to determine experimental conditions for optimal performance of an LC-ESI-MS/MS analysis is demonstrated. A stepwise strategy is proposed, which provides a controlled optimization procedure of the chromatographic quality (in terms of separation among the sample constituents) and maximizes the mass spectrometric signal of the selected product ions. Design of experiments (DOE) and response surface methodology are applied throughout the procedure. The stepwise approach has the advantage of dealing with the different optimization criteria separately, i.e. first ensuring sufficient chromatographic separation, then maximizing the amount of precursor ion entering the mass spectrometer, and finally generating high amounts of selected product ions. The experiments are performed on a linear ion trap mass spectrometer. Retention mapping using the band-tracking model is applied during LC development, which facilitates the optimization of segmented gradients. A set of different siderophores, strong iron chelates, is used as the model substances.

  • 29. Moberg, My
    et al.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Danielsson, Rolf
    Markides, Karin E
    Optimization strategy for liquid chromatography-electrospray ionization mass spectrometry methods2000Inngår i: Analyst, ISSN 0003-2654, Vol. 125, s. 1970-1976Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A strategy for the optimization of liquid chromatography (LC)–electrospray ionization mass spectrometry methods is proposed. The optimization aims at good chromatographic quality and a high signal-to-noise ratio for the analyte. The three-step strategy comprises screening experiments, LC studies and infusion experiments, using empirical modelling to evaluate the experimental data. The optimization route was examined for three different cases: (a) estriol in a mixture of estrogens, (b) ibuprofen and related metabolites in urine and (c) morphine in the presence of codeine

  • 30. Moberg, My
    et al.
    Markides, Karin E
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Multi-parameter investigation of tandem mass spectrometry in a linear ion trap using response surface modelling2005Inngår i: Journal Of Mass Spectrometry, ISSN 1076-5174, Vol. 40, nr 3, s. 317-324Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The feasibility of experimental design in combination with subsequent response surface modelling was illustrated for the prediction and interpretation of tandem mass spectrometric (MS/MS) fragmentation data using a linear quadrupole ion trap under various experimental conditions. The instrumental parameters included were (i) the pressure of the collision gas, (ii) the collision energy, (iii) the fill time of the linear ion trap and (iv) the scan rate. The spectral intensity and width of five fragment ions of the doubly charged neuro-active peptide bombesin were used for evaluation, and all experiments were performed so as to resemble the results obtained from a liquid chromatographic peak. The reported results show how fairly simple mathematical tools can be utilized successfully to describe fundamental mechanisms associated with multiple collisional activation and collision-induced dissociation processes without an extensively controlled experimental environment. Most beneficial, using the suggested approach, is the ability to study interaction (synergistic) effects between various parameters. As was realized from the results, many interaction effects are indeed significant. For example, the effect on the signal intensity of different collision gas pressure settings is strongly dependent on the settings of the other parameters. The described approach can easily be adopted for optimization purposes of any MS/MS experiment.

  • 31. Nilsson, S. L.
    et al.
    Andersson, C
    Sjöberg, Per J. R
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Petersson, Patrik
    Jörntén-Karlsson, Magnus
    Markides, Karin E
    Phosphate buffers in capillary electrophoresis/mass spectrometry using atmospheric pressure photo ionization and electrospray ionization2003Inngår i: Rapid Communication in mass spectrometry, ISSN 0951-4198, Vol. 17, nr 20, s. 2267-2272Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Capillary electrophoresis (CE) has been combined with atmospheric pressure photoionization (APPI) and electrospray ionization (ESI) for mass spectrometric (MS) detection. Separation conditions using potassium phosphate buffer and ammonium formate buffer have been compared for analysis of eleven pharmaceutical bases. The results showed improvements in separation efficiency and peak symmetry when phosphate buffer was used. The low flow in CE may enable utilization of these advances with MS detection. Compared with ESI, the APPI technique provided a cluster-free background. The enhanced signal-to-noise ratio in the total ion current (TIC) and the reduced spectral background indicated that the APPI process is less affected by non-volatile salts in the CE buffers. This results in a wider range of choice of CE buffers in CE/MS analysis when APPI is the ionization method.

  • 32. Nilsson, Sara L
    et al.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Jörntén-Karlsson, Magnus
    Petersson, Patrik
    Markides, Karin E
    A chemometric study of active parameters and their interaction effects in a nebulized sheath-liquid electrospray interface for capillary electrophoresis-mass spectrometry2004Inngår i: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 25, nr 13, s. 2100-2107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A chemometrics approach has been used for evaluating the effect of four experimental parameters when coupling capillary electrophoresis (CE) to electrospray ionization-mass spectrometry (ESI-MS). Electrospray voltage, sheath-liquid flow rate, nebulizing gas flow rate, and spray needle position in respect to the MS orifice were varied according to a full factorial design. In addition to main effects, two interaction effects could be identified as significant when measuring the peak intensity of the analytes, from a sample mixture containing peptides and pharmaceuticals. The first interaction effects, between the nebulizing gas flow rate and the sheath-liquid flow rate, and the second interaction effect, between the nebulizing gas flow rate and the spray position, could further explain the impact that these variables have on the spray performance. The number of theoretical plates and the baseline noise were also measured. The sheath-liquid flow was found to significantly affect the separation efficiency, while the noise level mainly was controlled by the nebulizing gas flow. The same factorial design was also used for a CE capillary with lower internal diameter (ID) and the effects of the same variables were compared on those capillaries using equal injection volume for both capillaries. Similar trends were obtained in both capillaries but capillary ID was shown to be a significant variable when evaluating both capillaries in a single model. It was found that a capillary with 25 m ID provided improved CE-MS performance over than corresponding 50 m ID capillary. Enhanced sensitivity was obtained using the narrow-bore capillary, and at lower sheath-liquid flow rate the 25 m ID capillary also gave rise to more efficient peaks.

  • 33.
    Norström, Sara
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Lundström, Ulla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Vestin, Jenny
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Aronsson, Andreas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Influence of dissolved organic carbon (DOC) on the water chemistry in two forested catchments2007Inngår i: Proceedings. International Humic Substances Society.11 th Nordic-Baltic Symposium, Functioning of NOM in Environment, Joensuu, Finland June 10-13, 2007, 2007Konferansepaper (Fagfellevurdert)
  • 34.
    Norström, Sara
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Vestin, Jenny L K
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Lundström, Ulla S
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Initial effects of wood ash application on the stream water chemistry in a boreal catchment in central Sweden2011Inngår i: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 221, nr 1-4, s. 123-136Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to increased whole-tree harvesting in Swedish forestry, concern has been raised that a depletion of nutrients in forest soil will arise. The Swedish Forest Agency recommends compensation fertilization with wood ash to ensure that unwanted effects are avoided in the nutrient balance of the forest soil and in the quality of surface water. In this investigation, the chemistry of two first-order streams, of which one was subjected to a catchment scale treatment with 3 tonnes of self-hardened wood ash/ha in the fall of 2004, was monitored during 2003-2006. Large seasonal variations in stream water chemistry made changes due to ash application difficult to detect, but evaluating the ash treatment effects through comparison of the stream water of the treated catchment with the reference was possible via statistical tools such as randomized intervention analysis in combination with cumulative sum charts. The wood ash application did not yield any significant effect on the pH in the stream water and hence did not affect the bicarbonate system. However, dissolved organic carbon increased, a previously unreported effect of WAA, bringing about an increase of organic anions in the stream water. The wood ash application also induced significant increases for Ca, Mg, K, Si, Cl and malonate, of which K was most prominent. Although significant, the changes induced by the wood ash application were all small compared to the seasonal variations. As a tool to counteract acidification of surface waters, WAA seems to have limited initial effects

  • 35.
    Norström, Sara H
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Vestin, Jenny L. K.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Lundström, Ulla S
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Initial effects of wood ash application to soil and soil solution chemistry in a small, boreal watershed2012Inngår i: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 187, s. 85-93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    With the conception that whole tree harvesting leads to an impoverishment of forest soils wood ash application is recommended, with the foremost benefits being increased pH in soil and subsequent surface waters, and recycling of nutrients from the wood ash.

    In this investigation a small boreal catchment in central Sweden was studied for two years before and two years after treatment with the maximum recommended dose, 3 tonnes/ha, of crushed, self-hardened wood ash. The sampling area was situated in a slope towards a stream, to include the effect on both recharge- and discharge areas with different soil constitutions. The soil solution chemistry, exchangeable pool of cations and potential heavy metal accumulation in berries were studied. Temporary increases in soil solution concentration were found for K in the recharge area and Ca and SO4 in the discharge area when comparing ashed and control areas. No change in exchangeable cations was observed during the study period, and no increase of heavy metals in bilberries did occur. These small changes in the constitution of the soil solution do not suggest wood ash application as a method to improve soil quality in an initial phase.

  • 36.
    Norström, Sara H
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Vestin, Jenny LK
    Swedish geotechnical institute.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Lundström, Ulla S
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Influences of dissolved organic carbon on stream water chemistry in two forested catchments in central Sweden2010Inngår i: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 101, nr 1-3, s. 229-241Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stream water chemistry in two headwater streams draining two small, adjacent catchments in Bispgården, central Sweden was studied during the 2003 and 2004 growing seasons. The two catchments closely resemble each other in regard to size, shape and drainage density, with the major difference found in the area of wetland lining the streambeds. The emphasis of the study was to investigate the stream water chemistry of these closely resembling catchments, regarding the quality and quantity of dissolved organic carbon (DOC) and its influence on the concentrations of di- and trivalent cations. The streams showed significant differences in the content and size distribution of DOC and in the distribution of cations between the different size fractions. For both streams the high flow events induced by precipitation influenced the chemistry of the streams through increase of organic matter and its associated cations. Fanbergsbäcken, with relatively low pH and high DOC concentration, had a greater amount of high molecular mass (HMM) DOC to which approximately 75% of Al and Fe and about 50% of Ca and Mg were associated. Gråbergsbäcken, with a higher pH and lower DOC level, had approximately 65% of Al, 40% of Fe and 30% of Ca and Mg associated to its HMM DOC fraction. Sixteen different low molecular mass organic acids were found in the stream water, of which oxalic and lactic acid were present in the highest concentrations.

  • 37.
    Olofsson, Madelen
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Analysis of hydroxamate siderophores in soil solution using liquid chromatography with mass spectrometry and tandem mass spectrometry with on-line sample preconcentration2015Inngår i: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 38, nr 19, s. 3305-3312Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A liquid chromatography-electrospray ionization-mass spectrometry method was developed to quantitatively and qualitatively analyze thirteen hydroxamate siderophores (ferrichrome, ferrirubin, ferrirhodin, ferrichrysin, ferricrocin, ferrioxamine B, D1, E and G, neocoprogen I and II, coprogen and triacetylfusarinine C). Samples were pre-concentrated on-line via switch-valve setup prior to analyte separation on a Kinetex C18 column. Gradient elution was performed using a mixture of an ammonium formate buffer and acetonitrile. Total analysis time including column conditioning was 20.5 minutes. Analyte were fragmented by applying collision induced dissociation, enabling structural identification via tandem mass spectrometry. Limit of detection values for the selected ion monitoring method ranged from 71 pM to 1.5 nM with corresponding values of two to nine times higher for the multiple reaction monitoring method. The liquid chromatography-mass spectrometry method resulted in a robust and sensitive quantification of hydroxamate siderophores as indicated by retention time stability, linearity, sensitivity, precision and recovery. The analytical error of the methods, assessed trough random-order, duplicate analysis of soil samples extracted with a mixture of 10 mM phosphate buffer and methanol, appears negligible in relation to between-sample variations. 

  • 38.
    Olofsson, Madelen
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Effects of mineral amendment on soil chemistry parameters reflecting microbial activity in a Swedish boreal forest soilManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Samples of apatite, biotite and oligoclase were incubated in different soil horizons of a boreal forest podzol in central Sweden. After four years, soil from the bulk and the surfaces of the minerals were extracted and analyzed in regard to fungal biomass, enzymatic activity, low molecular mass organic acids and hydroxamate siderophores.  The nutrient status of the study area was evaluated using historical data from foliar and soil solution analysis. Soil solution indicated a possible shortage of P in the mineral soil even though foliar content was above target levels. The foliar analysis instead revealed possible shortage of Fe. Apatite is the primary source of inorganic P in soil and biotite is rich in Fe compared to the soil at the site, and it was hypothesized that both minerals could be attractive sources of weatherable mineral nutrients, hence associated with higher microbial activity. Parameters measured as indicators of microbial activity revealed few significant (p<0.05) differences between the minerals and bulk soil in the O horizon, probably due to large variations among replicates, although an overall higher microbial activity was found in the bulk soil. In the E horizon a distinct trend appeared indicating higher levels of low molecular mass organic acids, enzymatic activity and fungal biomass associated with the biotite mineral, although this observation was only found to be significant for some of the parameters when analyzed individually. No clear trends were observed in the B horizon.

  • 39.
    Olofsson, Madelen
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Liquid Chromatography with Electrospray Ionization and Tandem Mass Spectrometry Applied in the Quantitative Analysis of Chitin-Derived Glucosamine for a Rapid Estimation of Fungal Biomass in Soil2016Inngår i: International Journal of Analytical Chemistry, ISSN 1687-8760, E-ISSN 1687-8779, artikkel-id 9269357Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This method employs liquid chromatography-tandem mass spectrometry to rapidly quantify chitin-derived glucosamine for estimating fungal biomass. Analyte retention was achieved using hydrophilic interaction liquid chromatography, with a zwitter-ionic stationary phase (ZIC-HILIC), and isocratic elution using 60 % 5 mM ammonium formate buffer (pH 3.0) and 40 % ACN. Inclusion of muramic acid, and its chromatographic separation from glucosamine, enabled calculation of the bacterial contribution to the latter. Galactosamine, an isobaric isomer to glucosamine, found in significant amounts in soil samples, was also investigated. The two isomers form the same precursor and product ions, and could not be chromatographically separated using this rapid method. Instead, glucosamine and galactosamine were distinguished mathematically, using the linear relationships describing the differences in product ion intensities for the two analytes. The m/z transitions of 180→72 and 180→84 were applied for the detection of glucosamine and galactosamine and that of 252→126 for muramic acid. Limits of detection were in the pico-molar range for all included analytes. The total analysis time was 6 min, providing a high sample through-put method.

  • 40.
    Olofsson, Madelen
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Norström, Sara
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Evaluation of sampling and sample preparation procedures for the determination of aromatic acids and their distribution in a podzol soil using liquid chromatography-tandem mass spectrometry2014Inngår i: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 232-234, s. 373-380Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work the distribution of free and weekly adsorbed aromatic acids (phthalic acid and ten phenolicacids; gallic, p-hydroxybenzoic, salicylic, vanillic, protocatechuic, p-coumaric, syringic, sinapic, ferulic and caffeicacid), which could participate in weathering and soil formation processes, were studied for O, E and Bhorizons in a podzol soil in central Sweden. For the analysis a simple and rapid quantitative and qualitative liquidchromatography–tandem mass spectrometry method (using gradient elution) was developed with LODs rangingfrom 5 to 25 nM. Different soil solution sampling techniques (tension-lysimeter and soil centrifugation) and soilextraction with either 10 mM phosphate buffer (pH 7.2) or 50:50 (v/v) 10 mM phosphate buffer:MeOHwere compared. All eleven acids were found in detectable or trace concentrations. The most abundant aromaticacids were vanillic and phthalic acid with concentrations around 1 μM for O and E horizon respectively.Lysimeter samples resulted in the lowest concentrations followed by centrifugation samples. Ingeneral, buffer:MeOH extraction resulted in the highest concentrations for the O horizon, likely due toMeOH's ability to compete for hydrophobic sites on soil organic matter (SOM). Then again, pure bufferwith its higher ion strength, interfering with the acids electrostatic interactions with clay particles, leads tohigher extracted concentrations for the E and B horizons. Since the efficiency of the extraction solutions, to alarge extent, depends on the sample properties, a general approach is hard to appoint. However, the extractionof substituted cinnamic acids is in general facilitated by adding MeOH to the extraction solution. The use of statisticalmethods for the evaluation of the results showed a large and significant difference in aromatic acid concentrationsreceived using different sampling techniques and sample preparations. In fact, sampling methodsresulted in higher variations in aromatic acid concentrations than sampled horizon.

  • 41.
    Pettersson, M.
    et al.
    Prosthetic Dentistry Department of Odontology Faculty of Medicine, Umeå University, Umeå.
    Kelk, P.
    Department of Integrative Medical Biology Faculty of Medicine, Umeå University, Umeå.
    Belibasakis, G. N.
    Section of Oral Microbiology and Immunology Institute of Oral Biology Center of Dental Medicine, University of Zürich, Zürich, Switzerland.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Molin Thorén, M.
    Prosthetic Dentistry Department of Odontology Faculty of Medicine, Umeå University, Umeå.
    Johansson, A.
    Molecular Periodontology Department of Odontology Faculty of Medicine, Umeå University, Umeå.
    Titanium ions form particles that activate and execute interleukin-1β release from lipopolysaccharide-primed macrophages2017Inngår i: Journal of Periodontal Research, ISSN 0022-3484, E-ISSN 1600-0765, Vol. 52, nr 1, s. 21-32Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background and Objective: Peri-implantitis is a destructive inflammatory process characterized by destruction of the implant-supporting bone. Inflammasomes are large intracellular multiprotein complexes that play a central role in innate immunity by activating the release of proinflammatory cytokines. Although inflammasome activation has previously been linked to periodontal inflammation, there is still no information on a potential association with peri-implantitis. The aim of this study was to examine cytotoxic and proinflammatory effects, including inflammasome activation, of metals used in dental implants, in an in vitro model, as well as from clinical tissue samples. Material and methods: Human macrophages were exposed to different metals [titanium (Ti), cobalt, chromium and molybdenum] in a cell-culture assay. Cytotoxicity was determined using the neutral red uptake assay. Cytokine secretion was quantified using an ELISA, and the expression of genes of various inflammasome components was analysed using quantitative PCR. In addition, the concentrations of interleukin-1β (IL-1β) and Ti in mucosal tissue samples taken in the vicinity of dental implants were determined using ELISA and inductively coupled plasma mass spectrometry, respectively. Results: Ti ions in physiological solutions stimulated inflammasome activation in human macrophages and consequently IL-1β release. This effect was further enhanced by macrophages that have been exposed to lipopolysaccharides. The proinflammatory activation caused by Ti ions disappeared after filtration (0.22 μm), which indicates an effect of particles. Ti ions alone did not stimulate transcription of the inflammasome components. The Ti levels of tissue samples obtained in the vicinity of Ti implants were sufficiently high (≥ 40 μm) to stimulate secretion of IL-1β from human macrophages in vitro. Conclusion: Ti ions form particles that act as secondary stimuli for a proinflammatory reaction.

  • 42. Samskog, Jenny
    et al.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Jacobsson, Sven P
    Markides, Karin E
    Miniaturized on-line proteolysis-packed capillary liquid chromatography-mass spectrometry for peptide mapping of lactate dehydrogenase2003Inngår i: Journal of Chromatography A, ISSN 0021-9673, Vol. 998, nr 1/2, s. 83-91Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, methodology was developed for on-line and miniaturized enzymatic digestion with liquid chromatographic (LC) separation and mass spectrometric (MS) detection. A packed capillary LC–MS system was combined with on-line trypsin cleavage of a model protein, lactate dehydrogenase, to provide an efficient system for peptide mapping. The protein was injected onto an enzymatic capillary reactor and the resulting peptides were efficiently trapped on a capillary trapping column. Different trapping columns were evaluated to achieve a high binding capacity for the peptides generated in the enzyme reactor. The peptides were further eluted from the pre-column and separated on an analytical capillary column by a buffer more suitable for the following an electrospray ionisation (ESI) MS process. An important aspect of the on-line approach was the desalting of peptides performed in the trapping column to avoid detrimental signal suppression in the ESI process. The developed on-line system was finally compared to a classical digestion in solution, with reference to peptide sequence coverage and sensitivity. It was shown that the on-line system gave more than 100% higher peptide sequence coverage than traditional digestion methods.

  • 43. Sjöberg, Per J
    et al.
    Bökman, C Fredrik
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Markides, Karin E
    A method for determination of ion distribution within electrosprayed droplets2001Inngår i: Analyticak Chemistry, ISSN 0003-2700, Vol. 73, nr 1, s. 23-28Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simplified method for determination of ion distribution within electrospray ionization droplets has been developed. The method is based on an electrospray ionization mass spectrometry equilibrium partitioning model recently developed by Enke (Enke, C. G. Anal. Chem. 1997, 69, 4885-4893). This "simple" method required only two samples to be analyzed at each solution composition compared to the method previously reported. Furthermore, as the same m/z value is monitored in both experiments, possible effects of the mass-dependent ion transmission in the quadrupole were eliminated. Tetraalkylammonium compounds with variable hydrophobicity were used as model compounds and the effect of methanol-water composition in the electrosprayed solution was studied. It was found, as expected, that the signal optimized at a high content of methanol in the electrosprayed solution. The distribution coefficient for analyte ions between the droplet surface and bulk solution maximize, however, at a lower content of methanol in the electrosprayed solution.

  • 44. Sjöberg, Per J. R.
    et al.
    Bökman, C. Fredrik
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Markides, Karin E
    Factors influencing the determination of analyte ion surface partitioning coefficients in electrosprayed droplets2001Inngår i: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, Vol. 12, nr 9, s. 1002-1010Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The observed response in mass spectrometry utilizing electrospray as a sample introduction technique can be affected by a number of factors. In this study a series of two-electrolyte systems was investigated and the mass spectrometric responses were modeled by the use of droplet surface partitioning coefficients and instrumental response factors according to a recently reported method (Sjo¨berg et al., Anal. Chem. 2001, 73, 23–28). The partitioning coefficient and the instrumental response factor were found to be affected by the chosen experimental conditions. Experimental parameters that were investigated include spray position relative to the orifice, spray potential, nebulizer and curtain gas flow rates, ionic strength, and organic content of the sprayed solution. The time history of the generated droplets turned out to be of importance to both the partitioning coefficients and the instrumental response factor. For example, a general increase in the surface partitioning coefficients for the tetrapentylammonium ion was initially observed when the spray was aiming closer to the sampling orifice. Furthermore, it was shown with a small amount of deuterium labeled electrolyte that the total ionic strength and not just the electrolyte concentration influence the instrumental response factor. (J Am Soc Mass Spectrom 2001, 12, 1002–1010)

  • 45.
    Svanedal, Ida
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Boija, Susanne
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Almesåker, Ann
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Persson, Gerd
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andersson, Fredrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Metal Ion Coordination, Conditional Stability Constants and Solution Behavior of Chelating Surfactant Metal Complexes2014Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, nr 16, s. 4605-4612Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Coordination complexes of some divalent metal ions with the DTPA (diethylenetriaminepentaacetic acid)-based chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of chelation and solution behavior. The headgroup of 4-C 12-DTPA contains eight donor atoms that can participate in the coordination of a metal ion. Conditional stability constants for five transition metal complexes with 4-C12-DTPA were determined by competition measurements between 4-C12-DTPA and DTPA, using electrospray ionization mass spectrometry (ESI-MS). Small differences in the relative strength between the coordination complexes of DTPA and 4-C12-DTPA indicated that the hydrocarbon tail only affected the chelating ability of the headgroup to a limited extent. The coordination of Cu2+ ions was investigated in particular, using UV-visible spectroscopy. By constructing Job's plots, it was found that 4-C12-DTPA could coordinate up to two Cu2+ ions. Surface tension measurements and NMR diffusometry showed that the coordination of metal ions affected the solution behavior of 4-C 12-DTPA, but there were no specific trends between the studied divalent metal complexes. Generally, the effects of the metal ion coordination could be linked to the neutralization of the headgroup charge of 4-C 12-DTPA, and the resulting reduced electrostatic repulsions between adjacent surfactants in micelles and monolayers. The pH vs concentration plots, on the other hand, showed a distinct difference between 4-C12-DTPA complexes of the alkaline earth metals and the transition metals. This was explained by the difference in coordination between the two groups of metal ions, as predicted by the hard and soft acid and base (HSAB) theory.

  • 46.
    Thurdin, Rickard T.
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    van Hees, P. A. W.
    Örebro University, Örebro.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Lundström, Ulla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bio fuel ash in a road construction: Impact on soil solution chemistry2006Inngår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 26, nr 6, s. 599-613Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Limited natural resources and landfill space and increasing amounts of ash produced from incineration of bio fuel and solid wastes have created a demand for useful applications of ash of which road construction is one. Here the environmental impact of a fly ash layer in a reconstructed road was evaluated by studying the soil solution chemistry in the ash layer, at two depths in the soil below and at two depths in the ditch using a centrifugation drainage technique. The road was situated about 20 km west of Sollefteå, (63˚ 16� 33�N, 17˚12�52�E) in the middle of Sweden. Two years after the application of the ash the concentrations of zinc were increasing in the ash layer solutions while concentrations of cadmium were stabilising. Below the ash layer in the road an initial increase of the pH was observed and the concentrations of potassium, sulphate and cadmium showed an increase while copper and mercury showed decreasing concentrations in the road and the ditch soil solutions. The concentrations in the ditch soil solutions were generally much lower compared to the road. Concentrations of calcium in the ash layer solutions indicated that hardening had taken place.

  • 47.
    Thurdin, Rikard
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Lundström, Ulla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    A comparison of sampling methods for environmental monitoring of ash road constructionManuskript (Annet vitenskapelig)
  • 48.
    Vestin, Jenny
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Lundström, Ulla
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Growth and chemical characterisation of Norway spruce grown on alkaline and non-alkaline soilManuskript (Annet vitenskapelig)
  • 49.
    Vestin, Jenny L K
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Lundström, Ulla S
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    The impact of alkaline and non-alkaline parent material on soil solution composition and tree growth: Focus on soils, muntlig presentation 0509152005Konferansepaper (Annet vitenskapelig)
  • 50.
    Vestin, Jenny L. K.
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Norström, Sara H
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Bylund, Dan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Lundström, Ulla S
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Soil solution and stream water chemistry in a forested catchment II: Influence of organic matter2008Inngår i: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 144, nr 2008, s. 271-278Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Differences between recharge and discharge areas in soil forming processes and nutrient conditions were observed in an earlier study of a catchment area in central Sweden (63°07′N, 16°70′E; Vestin, J.L.K., Norström, S.H., Bylund, D., Mellander, P-E., Lundström, U.S., submitted for publication to Geoderma. Soil solution and stream water chemistry in a forested catchment, I Dynamics.). To further examine the factors that determine the soil and stream water properties in the catchment area, the present study focused on the organic dynamics and the association of cations to different size fractions of organic matter. Six sampling plots were established in each of the recharge and discharge areas, respectively, with samples taken in June 2004. Dissolved organic carbon (DOC) and cation concentrations in the soil solution and stream water were determined. In the recharge area, low molecular mass (LMM) organics played an important role in transportation of several cations through the soil profile, inducing the podzolisation process by associating with Al and Fe. In the discharge area close to the stream, high molecular mass (HMM) organics appeared to play a crucial role in transportation of cations. Here the majority of recovered cations were associated with HMM organic matter, inhibiting the podzolisation process. The total concentration of C and DOC was higher than in the recharge area, and the concentration of cations increased with depth in the mineral soil. In the stream water, as in the discharge area soil solution, all carboxylic groups were associated to cations. Both Al and Fe were completely associated with the HMM DOC fraction, which indicated a rapid turnover of LMM DOC in stream water. Thus we conclude that DOC plays an important role in soil forming processes, and that its different size fractions have large effects on the transportation of elements in different soils and in stream water.

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