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  • 1.
    Shariatgorji, Mohammadreza
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Spacil, Zdenek
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Maddalo, Gianluca
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Cardenas, Lourdes B.
    Plant Biology Division, Institute of Biological Sciences, University of the Philippines Los Banos, College, Laguna 4031, The Philippines.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Matrix-free thin-layer chromatography/laser desorption ionization mass spectrometry for facile separation andidentification of medicinal alkaloids2009In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 23, no 23, p. 3655-3660Article in journal (Refereed)
    Abstract [en]

    Quaternary protoberberine alkaloids belong to a pharmaceutically important class of isoquinoline alkaloids associated with bactericidal, fungicidal, insecticidal and antiviral activities. As traditional medicine gains wider acceptance, quick and robust analytical methods for the screening and analysis of plants containing these compounds attract considerable interest. Thin-layer chromatography (TLC) combined with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a powerful technique but suffers from dilution of the TLC bands resulting in decreased sensitivity and masking of signals in the low-mass region both due to addition of matrix. This study integrates for the first time conventional silica gel TLC and laser desorption ionization mass spectrometry (LDI-MS) thus eliminating the need for any external matrix. Successful separation of berberine (Rf = 0.56) and palmatine (Rf = 0.46) from Berberis barandana including their identification by MS are demonstrated. Furthermore, a robust electrospray ionization (ESI)-MS method utilizing residual sample from TLC for quantification of berberine applying selected reaction monitoring and standard addition method is presented. The amount of berberine in the plant root prepared for the study was determined to be 0.70% (w/w). Copyright © 2009 John Wiley & Sons, Ltd.

  • 2.
    Spacil, Z
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Eriksson, J
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    LC-MS/MS identification of -N-methylamino-L-alanine in Cyanobacteria Chromatography and Tandem Mass Spectrometry2009Conference paper (Other academic)
  • 3.
    Spacil, Zdenek
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Eriksson, J
    Jonasson, S
    Bergman, B
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Identification of -N-methylamino-L-alanine (BMAA) in Cyanobacteria2009In: Abstracts / 12th EuCheMS International conference on chemistry and the environment: 14-17 June 2009, Stockholm university, Stockholm, Sweden, 2009Conference paper (Other academic)
  • 4.
    Spacil, Zdenek
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Eriksson, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Jonasson, Sara
    Stockholm University, Faculty of Science, Department of Botany.
    Rasmussen, Ulla
    Stockholm University, Faculty of Science, Department of Botany.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Analytical protocol for identification of BMAA and DAB in biologicalsamples2010In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 135, p. 127-132Article in journal (Refereed)
    Abstract [en]

     

    b

    -N-methylamino-L-alanine (BMAA) is a non-protein amino acid, thought to be inflicting neurodegenerative diseases related to ALS/PDC in human beings. Due to conflicting data concerning the presence of BMAA in various biological matrixes, we present a robust and sensitive method for high confidence identification of BMAA after derivatization by 6-aminoquinolyl-N

    -hydroxysuccinimidyl carbamate (AQC). The efficient sample pretreatment in combination with LC-MS/MS SRM enables chromatographic separation of BMAA from the isomer 2,3-diaminobutyric acid (DAB). The method is applicable for selective BMAA/DAB detection in various biological samples ranging from a prokaryotic cyanobacterium to eukaryotic fish.

  • 5.
    Spacil, Zdenek
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Novakova, Lucie
    Department of Analytical Chemistry, Faculty of Pharmacy, Charles University in Prague, Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic.
    Solich, Petr
    Department of Analytical Chemistry, Faculty of Pharmacy, Charles University in Prague, Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic.
    Analysis of phenolic compounds by high performance liquidchromatography and ultra performance liquid chromatography2008In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 76, no 1, p. 189-199Article in journal (Refereed)
    Abstract [en]

    Two novel chromatographic methods both based on utilization of sub-2-micron particle columns were developed for the analysis of phenolic compounds in this work. An HPLC system was equipped with C18 silica-based analytical column (50 mm × 4.6 mm, 1.8 μm) and a UPLC system with ethylene-bridged hybrid C18 analytical column (100 mm × 2.1 mm, 1.7 μm).

    In total 34 phenolic substances were divided into groups of phenolic acids, flavonoids, catechins and coumarins and were analysed in sequence using different gradient methods. System suitability test data, including repeatability of retention time and peak area, mean values of asymmetry factor, resolution, peak capacity and the height equivalent of a theoretical plate were determined for each gradient method by 10 replicate injections. The developed methods were applied in the analysis of real samples (grape wines, teas).

  • 6.
    Spacil, Zdenek
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Shariatgorji, Mohammadreza
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Amini, Nahid
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Solich, Petr
    Department of Analytical Chemistry, Faculty of Pharmacy, Charles University in Prague, Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Matrix-less laser desorption/ionisation mass spectrometry of polyphenols in red wine2009In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 23, no 12, p. 1834-1840Article in journal (Refereed)
    Abstract [en]

    Matrix-assisted laser desorption/ionisation (MALDI) of small molecules is challenging and in most cases impossible due to interferences from matrix ions precluding analysis of molecules <300-500 Da. A common matrix such as ferulic acid belongs to an important class of compounds associated with antioxidant activity. If the shared phenolic structure is related to the propensity as an active MALDI matrix then it follows that direct laser desorption/ionisation should be possible for polyphenols. Indeed matrix-less laser desorption/ionisation mass spectrometry is achieved whereby the analyte functions as a matrix and was used to monitor low molecular weight compounds in wine samples. Sensitivity ranging from 0.12-87 pmol/spot was achieved for eight phenolic acids (4-coumaric, 4-hydroxybenzoic, caffeic, ferulic, gallic, protocatechuic, syringic, vanillic) and 0.02 pmol/spot for trans-resveratrol. Additionally, 4-coumaric, 4-hydroxybenzoic, caffeic, ferulic, gallic, syringic, vanillic acids and trans-resveratrol were identified in wine samples using accurate mass measurements consistent with reported profiles based on liquid chromatography (LC)/MS. Minimal sample pre-treatment make the technique potentially appropriate for fingerprinting, screening and quality control of wine samples. Copyright © 2009 John Wiley & Sons, Ltd.

  • 7.
    Spáčil, Zdeněk
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Mass Spectrometry of Biologically Active Small Molecules: Focusing on polyphenols, alkaloids and amino acids2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The foci of this dissertation are on advanced liquid chromatography (LC) separation and mass spectrometry (MS) techniques for the analysis of small bioactive molecules. In addition to discussing general aspects of such techniques the results from analyses of polyphenols (PPs), alkaloids and amino acids published in five appended studies are presented and discussed. High efficiency and well understood principles make LC the method of choice for separating analytes in many kinds of scientific investigations. Moreover, when LC is coupled to an MS instrument, analytes are separated in two stages: firstly they are separated and pre-concentrated in narrow bands using LC and then separated according to their mass-to-charge (m/z) ratios in the MS instrument. Some MS instruments can provide highly accurate molecular weight measurements and mass resolution allowing identification of unknown compounds based purely on MS data, thus making prior separation unnecessary. However, prior separation is essential for analyzing substances in most complex matrices – especially useful is the ultra-high performance LC (UHPLC). The advantages of using UHPLC rather than HPLC for the analysis of PPs in tea and wine were evaluated in one of the studies this thesis is based upon. The phenolic composition of red wine was also examined, using a novel LDI technique, following solid phase extraction (SPE). A class of small aromatic molecules (medicinally important alkaloids) also proved to be amenable to straightforward analysis, by thin layer chromatography (TLC) work-up followed by LDI-MS. Finally, a LC-MS method for monitoring neurotoxins (β-N-methyl-amino-L-alanine and 2,3-diaminobutyric acid) in complex biological matrices was developed and applied. Overall, the studies show that careful attention to the physicochemical properties of analytes can provide insights that can greatly facilitate the development of alternative methods to analyze them, e.g. by LDI.

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