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  • 301.
    Olsson, Jeanette
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    New Techniques for Chiral Separations2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Gas chromatography (GC) has been utilized for the study of enantiomer resolution of the atropisomers of PCBs, o,p´-DDD and o,p´-DDT. Different substituents and concentrations of cyclodextrin, capillary dimensions and type of stationary phase films have been investigated to achieve the resolution of as many of the atropisomers on one column as possible. The results indicated that the butyl substitution of 6-hydroxyl and the methyl substitution of 2- and 3-hydroxyl were the most promising for the enantiomeric separation. Using Capillary Electrophoresis (CE), the trimers and monomers of PM-β-CDs were compared for enantiomeric resolution, as well as comparing the cationic PMMA-β-CD with the anionic HS-β-CD. In these studies the trimer did not show an improved resolution for mepivacaine, when compared to the equimolar concentration of the monomer. The cationic CD gave increased resolution values for ibuprofen when compared to the anionic CD. A scheme for reversing enantiomeric elution order of both the basic propranolol and acidic ibuprofen is also presented, with the aim of facilitating the detection of impurities in a high sample loading. The detection of 1% of each enantiomer of propranolol, and 1% of R(-)-ibuprofen, was demonstrated, with elution prior to the tailing peak of the corresponding enantiomer. Dimethylacrylamide-coated capillaries were used in this work, and the stability of this coating was demonstrated, giving a highly reduced electroosmotic flow for up to six months. Enantiomeric baseline separations of omeprazole and 5-hydroxyomeprazole have also been achieved with both CE and Open Tubular Capillary Electrochromatography (OT-CEC) methods. With CE-UV, both a non-aqueous method (using HDMS-β-CD) and an aqueous method (using HS-β-CD) were used for enantiomeric resolution of the two racemates. Resolution of omeprazole was also achieved using CE-Electrospray Ionization-Mass Spectrometry (ESI-MS). In OT-CEC, avidin was immobilized on the inside surface of a fused silica capillary and was employed as chiral selector for the enantiomeric baseline resolution of omeprazole and 5-hydroxyomeprazole.

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  • 302.
    Olsson, Jeanette
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Blomberg, Lars G.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Enantioseparation of Omeprazole and its Metabolite 5-Hydroxyomeprazole using Open Tubular Capillary Electrochromatography with Immobilized Avidin as Chiral Selector2008In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 875, no 1, p. 329-332Article in journal (Refereed)
    Abstract [en]

    The present paper demonstrates the enantiomeric separation of omeprazole and its metabolite 5-hydroxyomeprazole performed with open tubular capillary electrochromatography (OT-CEC). The protein avidin was used as the chiral selector. Avidin was immobilized by a Schiffs base type of reaction where the protein was via glutaraldehyde covalently bonded to the amino-modified wall of a fused-silica capillary, 50 μm i.d. Both racemates were baseline resolved. Resolution was 1.9 and 2.3, respectively, using ammonium acetate buffer, pH 5.8, 5% methanol, with UV-detection. These values of resolution using OT-CEC are higher than earlier published results regarding chiral separation of omeprazole and 5-hydroxyomeprazole on packed CEC. The number of theoretical plates also indicated good separation efficiency.

  • 303. Olsson, Jeanette
    et al.
    Marlin, Nicola D.
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Enantiomeric Separation of Omeprazole Enantiomers by Aqueous Capillary Electrophoresis using UV and MS detection2007In: Chromatographia, 66 (2007) 421-425Article in journal (Refereed)
  • 304. Olsson, Jeanette
    et al.
    Stegander, Filip
    Marlin, Nicola
    Wan, Hong
    Blomberg, Lars G
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Enantiomeric separation of omeprazole and its metabolite 5-OH-omeprazole using non-aqueous capillary electrophoresis,2006In: J. Chromatogr. A., 1129 (2006) 291-295Article in journal (Refereed)
  • 305.
    Olsson, Robert
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Lestelius, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science.
    Important fluid properties for Imbibition into Coating Layers2005Conference paper (Refereed)
  • 306.
    Olsson, Robert
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre.
    Yang, Li
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Lestelius, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Paper Surface Centre. Karlstad University, Faculty of Technology and Science, Materials Science.
    Flexographic ink transfer and setting due to coating polarity and printing conditions2006Conference paper (Refereed)
  • 307.
    Petersson, Patrik
    et al.
    AstraZeneca R&D Lund, SE-221 87 Lund, Sweden.
    Forssén, Patrik
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Edström, Lena
    Department of Physical and Analytical Chemistry, BMC Box 577, SE-751 23 Uppsala, Sweden.
    Samie, Farzad
    AstraZeneca Nordic Headquarters (ISMO), Södertälje.
    Tatterton, Stephen
    AstraZeneca R&D Charnwood, Loughborough, Leicestershire LE11 5RH, UK.
    Clarke, Adrian
    AstraZeneca R&D Charnwood, Loughborough, Leicestershire LE11 5RH, UK.
    Fornstedt, Torgny
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Why ultra high performance liquid chromatography produces more tailing peaks than high performance liquid chromatography, why it does not matter and how it can be addressed2011In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1218, no 39, p. 6914-6921Article in journal (Refereed)
    Abstract [en]

    The purpose of this study is to demonstrate, with experiments and with computer simulations based on a firm chromatographic theory, that the wide spread perception of that the United States Pharmacopeia tailing factor must be lower than 2 (Tf < 2) is questionable when using the latest generation of LC equipment. It is shown that highly efficient LC separations like those obtained with sub-2 μm porous and 2.7 μm superficially porous particles (UHPLC) produce significantly higher Tf-values than the corresponding separation based on 3 μm porous particles (HPLC) when the same amount of sample is injected. Still UHPLC separations provide a better resolution to adjacent peaks. Expressions have been derived that describe how the Tf-value changes with particle size or number of theoretical plates. Expressions have also been derived that can be used to scale the injection volume based on particle size or number of theoretical plates to maintain the Tf-value when translating a HPLC separation to the corresponding UHPLC separation. An aspect that has been ignored in previous publications. Finally, data obtained from columns with different age/condition indicate that Tf-values should be complemented by a peak width measure to provide a more objective quality measure.

  • 308.
    Pimrote, Wachirawan
    et al.
    Naresuan University, Phayao Campus, Thailand.
    Ratana-Ohpas, Roongroje
    Walailak University, Thailand.
    Renman, Lars
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    A Combination Bismuth Bulk Electrode and Its Use in Adsorptive Constant-Current Stripping Chronopotentiometry for Iron Using Solochrome Violet RS2011In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 23, no 7, p. 1607-1614Article in journal (Refereed)
    Abstract [en]

    A new combination bismuth bulk electrode allowing potentiostatic control to be maintained in a suspended sample drop is described. The electrode was tested by adsorptive constant-current stripping chronopotentiometry for iron-(III) using Solochrome Violet RS.

  • 309. Pruim, Peter
    et al.
    Öhman, Marcus
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Huo, Yuli
    Schoenmakers, Peter J.
    Kok, Wim Th.
    Methacrylate monolithic capillary columns for gradient peptide separations2008In: Journal of chromatography AArticle in journal (Refereed)
  • 310. Reekmans, S
    et al.
    Bernik, D
    Gehlen, M
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Van der Auweraer, M
    De Schryver F, F C
    Change in the Micellar Aggregation Number or in the Size Distribution? A Dynamic Fluorescence Quenching Study of Aqueous Cetyltrimethylammonium Chloride1993In: Langmuir, 1993, 9, 2289-2296Article in journal (Refereed)
  • 311.
    Renman, Lars
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Pimrote, Wachirawan
    Si Thammarat, Nakhon
    Determination of azo dye-based metal complexes by adsorptive stripping chronopotentiometry using a bismuth bulk electrode2010Conference paper (Refereed)
  • 312. Riklund, KE
    et al.
    Makiya, R
    Sundström, Birgitta
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Bäck, O
    Henriksson, R
    Ohietala, S
    Stigbrand, T
    Inhibition of growth of HeLa cell tumours in nude mice by 125I-labelled anticytokeratin and anti-PLAP monoclonal antibodies1991In: Anticancer Res 1991;11:555-560Article in journal (Refereed)
  • 313. Riklund, KE
    et al.
    Makiya, RA
    Sundström, Birgitta
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Thornell, L-E
    Stigbrand, T
    Experimental radioimmunotherapy of HeLa tumours in nude mice with 131I-labelled monoclonal antibodies1990In: Anticancer Res 1990;10:379-384Article in journal (Refereed)
  • 314. Riklund-Åhlström, K
    et al.
    Makiya, R
    Sundström, Birgitta
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Ullén, A
    Stigbrand, T
    Radioimmunotherapy of HeLa cell tumours grafted in nude mice, by a combination of 131I-labelled monoclonal antibodies agains PLAP and cytokeratin1995In: Tumor Targeting 1995;1:239-244Article in journal (Refereed)
  • 315. Roos, C
    et al.
    Stenke, L
    Ohm, L
    Widell, S
    Kumlin, M
    Lindgren, JA
    Tornhamre, Susanne
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Clinical imatinib mesylate treatment induces early normalisation of aberrant neutrophil leukotriene C4 synthase expression and activity in chronic myeloid leukaemia2008In: Br J Haematol. 2008 Sep;142(6):992-5Article in journal (Refereed)
  • 316.
    Roos, Cecilia
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Studies of leukotriene C4 synthase expression and regulation in chronic myeloid leukaemia2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Leukotriene (LT) C4 is generated through conjugation of LTA4 with glutathione by the actions of leukotriene C4 synthase (LTC4S). This biologically potent mediator of asthma and inflammation has also been suggested to play a regulatory role in human myelopoiesis and is overproduced by blood and bone marrow cells from patients with chronic myeloid leukaemia (CML).

    We investigated the expression and activity of LTC4S in normal and leukemic myeloid cells of different degrees of maturity. Normal cells displayed the highest expression and activity in the most immature cells, and it decreased with increasing maturity. The expression and activity of LTC4S followed the same pattern in corresponding CML cell fractions, however with a consistently higher expression and activity than seen in the normal cells. LTC4S could not be detected at the protein level in normal mature neutrophils but LTC4S mRNA could be amplified from total RNA. However, in cytoplasmic extracts from these cells LTC4S mRNA could not be detected.

    To study a possible posttranscriptional regulation we synthesised a LTC4S RNA. Cytosolic extracts from CML neutrophils, in contrast to normal neutrophil extracts, degraded this RNA, suggesting that the aberrant expression of LTC4S in CML neutrophils is not caused by stabilisation of LTC4S mRNA in the cytosol.

    We also show the first in vivo evidence of an increased LTC4S activity. Thus, CML patients were found to have significantly higher levels of the LTC4 metabolite LTE4 in their urine compared to healthy individuals.

    Imatinib is an inhibitor of BCR-ABL, a tyrosine kinase believed to induce and maintain the malignant transformation in CML. In vivo treatment with imatinib normalised the aberrant LTC4S expression seen in CML neutrophils. We could detect a significant decrease in LTC4S activity already within two weeks of therapy, without any effect on the presence of BCR-ABL.

    To further explore the possible connection between BCR-ABL and LTC4S, a CML cell line that expresses active LTC4S was identified. Surprisingly, upon treatment of KCL22 cells with imatinib there was a dose- and time-dependent increase in the enzyme activity. Real-time RT-PCR showed an increase in LTC4S mRNA levels, which could explain the increased enzyme activity.

    Taken together, the expression pattern of LTC4S during myeloid differentiation further implies a role for LTC4 in normal and leukemic myelopoiesis. The upregulated expression of LTC4S in CML seems to be a down-stream step in BCR-ABL-induced signalling.

  • 317.
    Roos, Cecilia
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Erlandsson, Ann
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Tornhamre, Susanne
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Effect of imatinib mesylate on leukotriene C4 synthase in a Philadelphia-positive cell lineManuscript (Other academic)
  • 318.
    Roos, Cecilia
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Stenke, Leif
    Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Sweden.
    Ohm, Lotta
    Division of Hematology, Karolinska University Hospital Solna, Karolinska Institutet, Sweden.
    Widell, Susanne
    Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Sweden.
    Kumlin, Maria
    Institute of Environmental Medicine, Division of Physiology, Unit for Experimental Asthma and Allergy Research, Karolinska Institutet, Sweden.
    Lindgren, Jan Åke
    Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Sweden.
    Tornhamre, Susanne
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Clinical imatinib mesylate treatment induces early normalisation of abberant neutrophil leukotriene C4 synthase expression and activity in chronic myeloid leukemia2008In: British Journal of Haematology, ISSN 0007-1048, E-ISSN 1365-2141, Vol. 142, no 6, p. 992-995Article in journal (Refereed)
  • 319.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Balance between photoactivation and photoinhibition of photosystem II in Chlamydomonas reinhardtii lacking the 23 kDa extrinsic subunit1995Conference paper (Refereed)
  • 320.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Changes in the oxidation state of cytochrome b-559 and tyrosine-D during in vivo photoactivation of phgotosystem II1998In: Garab, G (ed.) Photosynthesis:Mechanisms and Effects, Vol II pp 1097-1100,Article in journal (Refereed)
  • 321.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Coupled modification of the acceptor side of photosystem II during photoactivation of the oxygen evolving complex1998Report (Other academic)
  • 322.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Coupled modification of the acceptor-side of photosystem II during photoactivation of the oxygen evolving complex1998Report (Other academic)
  • 323.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Photoactivation and photoinhibition of photosystem II in a mutant of Chlamydomonas reinhardtii lacking the 23 kDa extrinsic subunit1995Other (Other (popular science, discussion, etc.))
  • 324.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Photoactivation is less efficient in a mutant of Chlamydomonas reinhardtii lacking the 23 kDa extrinsic subunit of Photosystem II1996Other (Other (popular science, discussion, etc.))
  • 325.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Protection of photosystem II from Photodamage during the Assembly of the Water Oxidizing Complex1999In: Ph.D. Thesis, Lund UniversityArticle in journal (Refereed)
  • 326.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Studies of oxygen evolution and photoinhibition in a photosystem II mutant of Chlamydomonas reinhardtii1993Report (Other academic)
  • 327.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Studies of oxygen evolution and photoinhibition in a photosystem II mutant of Chlamydomonas reinhardtii1993Report (Other academic)
  • 328.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    The 23 kDa extrinsic subunit of PS II is essential for efficient photoactivation1996Other (Other (popular science, discussion, etc.))
  • 329.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    The balance between photoactivation and photoinhibition studied in a mutant of Chlamydomonas reinhardtii lacking the 23 kDa extrinsic subunit of PS II1994Report (Other academic)
  • 330.
    Rova, Maria
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    The interrelationship between photoactivation and photoinhibition in a mutand of Chlamydomonas reinhardtii lacking the 23 kDa psb P protein of photosystem II1994Report (Other academic)
  • 331.
    Rova, Maria
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Franzén, Lars-Gunnar
    Department of Biochemistry, Arrhenius laboratories of Natural Science.
    Fredriksson, Per-Olof
    Styring, Stenbjörn
    Photosystem II in a mutant of Chlamydomonas reinhardtii lacking the 23 kDa psb protein shows increased sensitivity to photoinhibition in the absence of chloride1994In: Photosynthesis Research, Vol. 39, no 1, p. 77-83-Article in journal (Refereed)
  • 332.
    Rova, Maria
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Franzén, Lars-Gunnar
    Fredriksson, Per-Olof
    Styring, Stenbjörn
    Photosystem II in a mutant of Chlamydomonas reinhardtii lacking the 23kDa psbP protein shows increased sensitivity to photoinhibition in the absence of chloride1994In: Photosynthesis Research, ISSN 0166-8595, E-ISSN 1573-5079, Vol. 39, p. 75-83Article in journal (Refereed)
  • 333.
    Rova, Maria
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Mamedov, Fikret
    Magnusson, Ann
    Fredriksson, Per-Olof
    Styring, Stenbjörn
    Coupled Activation of the Donor and the Acceptor Side of Photosystem II during Photoactivation of the Oxygen Evolving Cluster1998In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 37, p. 11039-11045Article in journal (Refereed)
  • 334.
    Rova, Maria
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Mc Ewen, Birgitta
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Fredriksson, Per-Olof
    Styring, Stenbjörn
    Balance between photoactivation and photoinhibition of photosystem II in Chlamydomonas reinhardtii lacking the 23 kDa extrinsic subunit1995Conference paper (Other (popular science, discussion, etc.))
  • 335.
    Rova, Maria
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Mc Ewen, Birgitta
    Karlstad University, Division for Environmental Sciences.
    Fredriksson, Per-Olof
    Styring, Stenbjörn
    Photoactivation and Photoinhibition Are Competing in a Mutant of Chlamydomonas reinhardtii Lacking the 23-kDa Extrinsic Subunit of Photosystem II1996In: The Journal of Biological Chemistry, Vol. 271, no 46, p. 28918-28924Article in journal (Refereed)
  • 336.
    Said, Rana
    et al.
    Huddinge Univ Hosp, Dept Clin Pharmacol, S-17176 Stockholm, Sweden..
    Kamel, Mohamed
    Huddinge Univ Hosp, Dept Clin Pharmacol, S-17176 Stockholm, Sweden..
    El-Beqqali, Aziza
    Huddinge Univ Hosp, Dept Clin Pharmacol, S-17176 Stockholm, Sweden..
    Abdel-Rehim, Mohamed
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad Univ, Dept Chem & Biomed Sci, Fac Sci & Technol, S-65188 Karlstad, Sweden.;AstraZeneca R&D, Dept Clin Pharmacol, S-15185 Sodertalje, Sweden.;AstraZeneca R&D, DMPK, S-15185 Sodertalje, Sweden..
    Microextraction by packed sorbent for LC-MS/MS determination of drugs in whole blood samples2010In: Bioanalysis, ISSN 1757-6180, E-ISSN 1757-6199, Vol. 2, no 2, p. 197-205Article in journal (Refereed)
    Abstract [en]

    Background: Microextraction by packed sorbent (MEPS) is used as an online sample-preparation method. The determination of local anesthetics lidocaine, ropivacaine and bupivacaine directly in human blood was performed using MEPS online with LC-MS/MS. Results: The range of the calibration curves in whole blood was 10-10000 nmol/l. The lower limit of quantification was set to 10.0 nmol/l. The accuracy of the quality control samples ranged from 85 to 97%. The interday precision of the studied analytes was within the range 1-5%. The regression correlation coefficient (r(2)) was over 0.995 for all runs. The present method is rapid, reliable and robust and may be used for therapeutic drug monitoring of studied analytes in whole blood. Conclusion: This assay allows the analysis of drugs in human blood directly. Sample preparation is simple and automated. The assay reduced the handling time and the cost, and could handle small volumes of whole blood samples (25 mu l).

  • 337.
    Samuelsson, Jörgen
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Enmark, Martin
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Forssén, Patrik
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Fornstedt, Torgny
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Highlighting Important Parameters Often Neglected in Numerical Optimization of Preparative Chromatography2012In: Chemical Engineering & Technology, ISSN 0930-7516, E-ISSN 1521-4125, Vol. 35, no 1, p. 149-156Article in journal (Refereed)
    Abstract [en]

    When a chromatographic separation process is numerically optimized, a number of input parameters to the column model need to be accurately determined, and the accuracy will affect the reliability of the predicted optimal operational conditions. Furthermore, the numerical accuracy of the solution to the column model will have similar impact. The input parameters holdup volume, injection profiles, and the selection of an algorithm for solving the column model were investigated. Errors in parameters or a numerical error in the solution of the column model were found to lead to a prediction of a product fraction where the set purity and/or yield requirements are not met.

  • 338.
    Samuelsson, Jörgen
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Enmark, Martin
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Högblom, Joakim
    Eka Chemicals.
    Forssén, Patrik
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Fornstedt, Torgny
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Characterization of adsorption in SFC: An evaluation of methods used in LC2012Conference paper (Refereed)
    Abstract [en]

    Recently the pharmaceutical industry has started to replace HPLC with SFC because of incentives to lower the environmental impact and as well as increasing performance. Reliable characterization of the adsorption processes in SFC, is therefore of utmost importance. The key thermodynamic phase system information is obtained by rigorous determination of adsorption isotherms over a broad concentration range. If properly processed, this data gives not only correct information about the degree of heterogeneity but also the values of the energy of interactions and monolayer capacities of each individual type of adsorption site in the phase system; ultimately, this can result in identification of the types of interactions (dipole-dipole, van der Waals interactions etc.). In this study, we will present the transfer of LC adsorption characterization methods to SFC conditions using several model compounds with several different methods for adsorption isotherm determination traditionally applied with success in LC, and now modified for SFC. We have limited our investigation to methanol as modifier and used the operational conditions, temperature and backpressure most typically observed in industrial settings; in addition, we have used commercial standard SFC-equipment. The results clearly shows that adsorption isotherm determinations in SFC are considerably more complicated than in LC; we will go through the most important pitfalls and give guidelines for more rigorous determinations of adsorption data in SFC. This is an industrial – academic cooperation in the Fundamental Separation Science Group www.separationscience.se

  • 339.
    Samuelsson, Jörgen
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Fornstedt, Torgny
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Recent Developments on the Elution by Characteristic Points Method for Rapid and Accurate Determination of Adsorption Isotherms2011Other (Other academic)
    Abstract [en]

    Adsorption isotherms are the most important pieces of information needed to understand the analytical and preparative separation system. Several methods are used for their determinations. In this poster we will analyze the elution by characteristic point method (ECP) that is faster and also consumes less amounts analyte and solvent as compared to classic methods such as the frontal analysis (FA) and the perturbation peak method. Classically, ECP is conducted by integrating the diffuse part of an overloaded elution profile, which means that just one single overloaded elution profile and a calibration curve is needed to determine the adsorption isotherm. However, the ECP method is derived assuming that the column has infinite efficiency and that the injection profile is rectangular. All deviation from this will lead to errors in the determined adsorption isotherm. Because the adsorption isotherm is also integrated, a continuous diffuse part of the elution profiles is required. This means that adsorption isotherms from only tailing and fronting peaks could classically only be determined. In this poster we will present: (i) A method to experimentally achieve rectangular injection-profiles [1]. (ii) Determination of the raw slope of the adsorption isotherm data without integrating the elution profile. (iii) Strategies to expand the ECP method for the determination of more complex adsorption isotherms including such containing inflection points [3]. [1] J. Samuelsson, T. Fornstedt, Anal. Chem. 80 (2008) 7887. [2] J. Samuelsson, T. Undin, A. Törncrona, T. Fornstedt, J. Chromatogr. A 1217 (2010) 7215. [3]. J. Samuelsson, T. Undin, T. Fornstedt, J. Chromatogr. A, under review

  • 340.
    Samuelsson, Jörgen
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Fornstedt, Torgny
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Forssén, Patrik
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Högblom, Joakim
    Eka Chemicals.
    A Holistic View on Optimization of Preparative Liquid Chromatography – Importance of Column Properties and Design.2012Conference paper (Refereed)
    Abstract [en]

    Several important studies based on firm theory ground - have been made on the different parameters of importance in chromatographic process optimizations during the recent years. In this presentation we take an holistic view by investigating i) the relative importance of the operational parameters and column properties and ii) how these effect the optimal column design. For optimization we used an advanced global response surface method combined with local gradient methods. As a model system we used the practical problem of purification of one or both optical isomers of a racemate. In the first part, we investigated the relative importance of stationary phase characteristics such as: (i) the retention factor, (ii) the selectivity, (iii) the saturation capacity (iv), the efficiency and (v) the maximum allowed operational pressure. In the second part we investigated how the optimal column design for a preparative separation problem is affected by column properties, such as particle size, and optimization constraints, such as required yield. The investigation showed – in contrast to what is generally believed – that the saturation capacity of the stationary phase is of minor importance, instead the maximum allowed operational pressure is one of the most important parameter. Moreover, smaller size packing materials always shows much lower solvent consumption. This is a great environmental and economical advantage of using smaller packing materials. Rules of thumbs, derived from the holistic optimizations, will be given for industrial preparative settings in the batch mode.

  • 341.
    Samuelsson, Jörgen
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Undin, Torgny
    Uppsala University.
    Fornstedt, Torgny
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Expanding the elution by characteristic point method for determination of various types of adsorption isotherms2011In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 24, p. 3737-3742Article in journal (Refereed)
    Abstract [en]

    Important improvements have recently been made on the elution by characteristic point (ECP) method to increase the accuracy of the determined adsorption isotherms. However, the method has so far been limited/used for only type I adsorption isotherms (e.g. Langmuir, Tóth, bi-Langmuir). In this study, general strategies are developed to expand the ECP method for the determination of more complex adsorption isotherms including such containing inflection points. We will exemplify the methodology with type II, type III and type V isotherms. Guidelines are given for how to determine such isotherms using the ECP method and for the experimental considerations that must be taken into account or that may be eliminated in the particular case.

  • 342.
    Samuelsson, Jörgen
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Undin, Torgny
    Uppsala University, Sweden.
    Törncrona, Anders
    Eka Chemicals AB, Sweden.
    Fornstedt, Torgny
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Improvement in the generation of adsorption isotherm data in the elution by characteristic points method-: the ECP-slope approach2010In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1217, no 46, p. 7215-7221Article in journal (Refereed)
    Abstract [en]

    The elution by characteristic points (ECP) method is a very rapid and precise method for determination of the phase system equilibrium of phase systems in broad solute concentration ranges. Thus, the method is especially suitable for rapid characterization of high efficient separation systems. One important source of error, the effects by the post-loop dispersion, was eliminated in a recent investigation. In this study, the systematic error caused by the selection of the integration starting point at concentration equal to 0 is eliminated. This is done by developing and validating a new procedure for isotherm data generation; the ECP-slope method. The method generates raw slope data of the adsorption isotherm instead of raw adsorption data by integrations as the classical ECP does. Both numerical and experimental data were used for the comparison of the classical ECP approach with the slope-ECP method

  • 343.
    Samuelsson, Jörgen
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Ņsberg, Dennis
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Enmark, Martin
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Fornstedt, Torgny
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Forssén, Patrik
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Modeling Competitive Adsorption Isotherms in Gradient Elution Nonlinear Reversed Phase Liquid Chromatography.2012Conference paper (Refereed)
    Abstract [en]

    Several important studies – based on firm theory ground - have been made on the different parameters of importance in chromatographic process optimizations during the recent years. In this presentation we take an holistic view by investigating i) the relative importance of the operational parameters and column properties and ii) how these effect the optimal column design. For optimization we used an advanced global response surface method combined with local gradient methods. As a model system we used the practical problem of purification of one or both optical isomers of a racemate. In the first part, we investigated the relative importance of stationary phase characteristics such as: (i) the retention factor, (ii) the selectivity, (iii) the saturation capacity (iv), the efficiency and (v) the maximum allowed operational pressure. In the second part we investigated how the optimal column design for a preparative separation problem is affected by column properties, such as particle size, and optimization constraints, such as required yield. The investigation showed – in contrast to what is generally believed – that the saturation capacity of the stationary phase is of minor importance, instead the maximum allowed operational pressure is one of the most important parameter. Moreover, smaller size packing materials always shows much lower solvent consumption. This is a great environmental and economical advantage of using smaller packing materials. Rules of thumbs, derived from the holistic optimizations, will be given for industrial preparative settings in the batch mode.

  • 344. Sau, S
    et al.
    Solanki, B.
    Orprecio, R.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences. Karlstad University, Faculty of Technology and Science, Materials Science.
    Evans, CH
    Higher-Order Cyclodextrin Complexes: The Naphthalene System2004In: J. Inclusion Phenom. Macrocyclic Chem., 2004, 48, 173-180Article in journal (Refereed)
  • 345.
    Sjöde, Anders
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Chemical characterization in the biorefinery of lignocellulose: Formation and management of oxalic acid and analysis of feedstocks for bioethanol production2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The pulp and paper industry is entering a new era. Pulp mills will be transformed to biorefineries that produce not only pulp, but also biofuels and novel products from lignocellulose. This thesis addresses problems connected with the industrial transition to environmental-friendly technologies and the implementation of the biorefinery concept.

    Peroxide bleaching and enhanced recirculation of process water may lead to increased problems with oxalate scaling. Enzymatic elimination of the oxalate problem could be the ultimate industrial solution. The activities of oxalate oxidase, oxalate decarboxylase and a novel oxalate-degrading enzyme provided by Novozymes have been tested in industrial bleaching filtrates. Chemical characterization of the filtrates was used in combination with multivariate data analysis to identify potential enzyme inhibitors. A method based on oxalate oxidase was developed to determine the levels of oxalic acid in process water.

    The precursors of oxalic acid formed during bleaching of pulp have been reassessed. New experimental data indicate that alkaline oxidative degradation of dissolved carbohydrates is the main source of oxalic acid. These findings are contradictory to previous hypotheses, which have been focused on lignin. Xylan was more important than lignin as precursor of oxalic acid under peroxide-bleaching conditions. Hot-water extraction of hemicelluloses from softwood mechanical pulp prior to the peroxide-bleaching stage reduced the formation of oxalic acid by one third.

    Lignocellulosic materials were characterized chemically with regard to their suitability as feedstocks in biorefineries producing bioethanol. Four agricultural and agro-industrial residues were investigated; cassava stalks, peanut shells, rice hulls, and sugarcane bagasse. Pretreated sugarcane bagasse was the material that was most susceptible to hydrolysis by cellulolytic enzymes. Waste fiber sludges from three pulp mills were characterized. The waste fiber sludge with the lowest content of lignin was hydrolyzed most efficiently by the enzymes. Oligomeric xylan fragments were isolated as by-products from a waste fiber sludge. Hydrolysis of the waste fiber sludges resulted in solid residues with improved fuel properties. The waste fibers were found to be suitable as a feedstock for the production of biofuels in a pulp mill-based biorefinery.

  • 346.
    Sjöde, Anders
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Jönsson, Leif J.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Nilvebrant, Nils-Olof
    STFI-Packforsk AB, Swedish Pulp and Paper Research Institute, Stockholm.
    Xylan is more important than lignin as precursor of oxalic acid during peroxide bleaching of mechanical pulpManuscript (Other academic)
  • 347.
    Sjöde, Anders
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Winestrand, Sandra
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Nilvebrant, Nils-Olof
    STFI-Packforsk AB, Swedish Pulp and Paper Research Institute, Stockholm.
    Jönsson, Leif J.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Enzyme-based control of oxalic acid in the pulp and paper industry2008In: Enzyme and microbial technology, ISSN 0141-0229, E-ISSN 1879-0909, Vol. 43, p. 78-83Article in journal (Refereed)
  • 348.
    Smedja Bäcklund, Anna
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    c Cytochromes as Electron Carriers in Microbial Chlorate Respiration2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Microbial respiration of oxochlorates is important for the biotreatment of effluents from industries where oxochlorates are produced or handled. Several bacterial species are capable to use perchlorate and/or chlorate as an alternative electron acceptor in absence of oxygen. The present study deals with the electron transport from the membrane-bound components to the periplasmic chlorate reductase, in the gram-negative bacterium Ideonella dechloratans. Both chlorate reductase and the terminal oxidase of I. dechloratans were found to utilize soluble c cytochromes as electron donors. For further investigation, two major heme-containing components were purified and characterized. The most abundant was a 9 kDa c-type cytochrome (class I), denoted cytochrome c-Id1. This protein was shown to serve as electron donor for both chlorate reductase, and for a terminal oxidase. The other major component was a 55 kDa homotetrameric cytochrome c', (class II). A function for this cytochrome could not be demonstrated but it does not appear to serve as electron donor to chlorate reductase. A gene predicted to encode a soluble c cytochrome was found in close proximity to the gene cluster for chlorate reduction. The predicted sequence did not match any of the cytochromes discussed above. The gene was cloned and expressed heterologously, and the resulting protein was investigated as a candidate electron donor for chlorate reductase. Electron transfer from this protein could not be demonstrated, suggesting that the gene product does not serve as immediate electron donor for chlorate reductase.

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  • 349.
    Smedja Bäcklund, Anna
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Electron transport in microbial chlorate respiration2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Several bacterial species are capable to use perchlorate and/or chlorate as an alternative electron acceptor in absence of oxygen. Microbial respiration of oxochlorates is important for biotreatment of effluent from industries where oxochlorates are produced or handled. One of these species, the Gram-negative Ideonella dechloratans, is able to reduce chlorate but not perchlorate. Two soluble enzymes, chlorate reductase and chlorite dismutase, participate in the conversion of chlorate into chloride and molecular oxygen. The present study deals with the electron transport from the membrane-bound components to the periplasmic chlorate reductase. Soluble c cytochromes were investigated for their ability to serve as electron donors to chlorate reductase. The results show that a 6 kDa c cytochrome serves as electron donor for chlorate reductase. This cytochrome also serves as electron donor for a terminal oxidase in the reduction of oxygen that is produced in the course of chlorate respiration. A gene encoding a soluble c cytochrome was found in close proximity to the gene cluster for chlorate reduction. This gene was cloned and expressed heterologously, and the resulting protein was investigated as a candidate electron donor for chlorate reductase. Electron transfer from this protein could not be demonstrated, suggesting that the gene product does not serve as immediate electron donor for chlorate reductase.

     

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  • 350.
    Smedja Bäcklund, Anna
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Bohlin, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Gustavsson, Niklas
    Department of Biochemistry, Lund University.
    Nilsson, Thomas
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Periplasmic c Cytochromes and Chlorate Reduction in Ideonella dechloratans2009In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 75, p. 2439-2445Article in journal (Refereed)
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