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  • 1.
    Bylund, Dan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Norström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Essén, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Analysis of low molecular mass organic acids in natural waters by ion exclusion chromatography tandem mass spectrometry2007In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1176, no 1-2, p. 89-93Article in journal (Refereed)
    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.

  • 2.
    Fredriksson, Mattias
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Petersson, Patrik
    AstraZeneca.
    Axelsson, Bengt-Olof
    AstraZeneca.
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    A component tracking algorithm for accelerated and improved liquid chromatography-mass spectrometry method development2010In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1217, no 52, p. 8195-8204Article in journal (Refereed)
    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.

  • 3.
    Fredriksson, Mattias
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Petersson, Patrik
    Jörntén-Karlsson, Magnus
    Axelsson, Bengt-Olof
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    An objective comparison of pre-processing methods for enhancement of liquid chromatography-mass spectrometry data2007In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1172, no 2, p. 135-150Article in journal (Refereed)
    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.

  • 4. Moberg, My
    et al.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Markides, Karin
    Novel approach to the determination of structurally similar hydroxamate siderophores by column-switching capillary liquid chromatography coupled to mass spectrometry2003In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1020, no 1, p. 91-97Article in journal (Refereed)
    Abstract [en]

    In this study a new approach to determine three different siderophores (ferrichrome, ferrichrysin, ferricrocin) in natural soil solutions as well as in cultures of fungi is presented. The method includes enrichment of the analytes on a short pre-column, packed with C18 material, and subsequent highly selective separation of the analytes on a capillary porous graphitic carbon (PGC) column. In contrast to normal C18 packing materials, porous graphitic carbon offers chromatographic resolution between the three very similar analytes. The selectivity of the method is enhanced even further by the electrospray ionization (ESI) mass spectrometric detection. The combination of a short pre-column and a packed capillary separation column results in a method with high sensitivity. Reported detection limits, defined as the concentration giving the signal-to-noise ratio 3:1, is 27.7 pM for ferrichrome, 46.1 pM for ferricrocin and 37.4 pM for ferrichrysin.

1 - 4 of 4
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