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  • 1. Abel, S
    et al.
    Bäbler, Matthäus
    ETH, Inst Chem & Bioengn, Dept Chem & Appl Biosci.
    Arpagaus, C
    Mazzotti, M
    Stadler, J
    Two-fraction and three-fraction continuous simulated moving bed separation of nucleosides2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1043, no 2, p. 201-210Article in journal (Refereed)
    Abstract [en]

     A new experimental set-up and a new simulated moving bed (SMB) operation are presented in this work. A desktop SMB unit developed as a modification of the commercial AKTA(TM) explorer working platform has been utilized for the separation of different mixtures of nucleosides. Both two fraction and three fraction SMB separations have been carried out, the latter made possible by the adoption of a new SMB configuration and operating mode (three fraction SMB, 3F-SMB, operation). Experiments demonstrate the feasibility of the 3F-SMB operation, and confirm the trends predicted based on considerations about retention of the components to be separated along the unit. 

  • 2.
    Agaton, Charlotta
    et al.
    KTH, Superseded Departments, Biotechnology.
    Falk, Ronny
    KTH, Superseded Departments, Biotechnology.
    Uhlén, Mathias
    KTH, Superseded Departments, Biotechnology.
    Hober, Sophia
    KTH, Superseded Departments, Biotechnology.
    Selective enrichment of monospecific polyclonal antibodies for antibody-based proteomics efforts2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1043, p. 33-40Article in journal (Refereed)
    Abstract [en]

    A high stringency protocol, suitable for systematic purification of polyclonal antibodies, is described. The procedure is designed to allow the generation of target protein-specific antibodies suitable for functional annotation of proteins. Antibodies were generated by immunization with recombinantly produced affinity-tagged target proteins. To obtain stringent recovery of the antibodies, a two-step affinity chromatography principle was devised to first deplete the affinity tag-specific antibodies followed by a second step for affinity capture of the target protein-specific antibodies. An analytical dot-blot array system was developed to analyze the cross-reactivity of the affinity-purified antibodies. The results suggest that the protocol can be used in a highly parallel and automated manner to generate mono-specific polyclonal antibodies for large-scale, antibody-based proteomics efforts, i.e. affinity proteomics.

  • 3. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Solid-phase extraction and gas chromatographic-mass spectrometric identification of degradation products from enhanced environmentally degradable polyethylene1995In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 690, no 2, p. 207-217Article in journal (Refereed)
  • 4.
    Aldaeus, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Lin, Yuan
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Amberg, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Roeraade, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Multi-step dielectrophoresis for separation of particles2006In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1131, no 1-2, p. 261-266Article in journal (Refereed)
    Abstract [en]

    A new concept for separation of particles based on repetitive dielectrophoretic trapping and release in a flow system is proposed. Calculations using the finite element method have been performed to envision the particle behavior and the separation effectiveness of the proposed method. As a model system, polystyrene beads in deionized water and a micro-flow channel with arrays of interdigited electrodes have been used. Results show that the resolution increases as a direct function of the number of trap-and-release steps, and that a difference in size will have a larger influence on the separation than a difference in other dielectrophoretic properties. About 200 trap-and-release steps would be required to separate particles with a size difference of 0.2%. The enhanced separation power of dielectrophoresis with multiple steps could be of great importance, not only for fractionation of particles with small differences in size, but also for measuring changes in surface conductivity, or for separations based on combinations of difference in size and dielectric properties.

  • 5. Anderson, M. E.
    et al.
    Aslan, D.
    Clarke, A.
    Roeraade, Johan
    KTH, Superseded Departments, Chemistry.
    Hagman, G.
    Evaluation of generic chiral liquid chromatography screens for pharmaceutical analysis2003In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1005, no 02-jan, p. 83-101Article in journal (Refereed)
    Abstract [en]

    Two different automated generic liquid chromatography screens for the separation of chiral compounds of pharmaceutical interest have been evaluated. The test set comprised 53 chemically diverse chiral compounds involving 55 enantiomeric pairs from the pharmaceutical industry (i.e. starting materials, synthetic intermediates and drug substances). The first screen utilised four polysaccharide-based columns with five mobile phases and showed enantioselectivity for 87% of the test compounds. The second screen employed three macrocyclic glycopeptide columns with two mobile phases and showed enantioselectivity for 65% of the test compounds. Merging of the two screening procedures resulted in an enantioselectivity for 96% of the chiral compounds. It is anticipated that the systematic use of the automated chiral HPLC screens described in this report will substantially reduce the necessary time for method development of pharmaceutically related chiral analytical methods.

  • 6.
    Andersson, Robert
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    On-line gas chromatographic analysis of higher alcohol synthesis products from syngas2012In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1247, p. 134-145Article in journal (Refereed)
    Abstract [en]

    An on-line gas chromatographic (GC) system has been developed for rapid and accurate product analysis in catalytic conversion of syngas (a mixture of H-2 and CO) to alcohols, so called "higher alcohol synthesis (HAS)". Conversion of syngas to higher alcohols is an interesting second step in the route of converting coal, natural gas and possibly biomass to liquid alcohol fuel and chemicals. The presented GC system and method are developed for analysis of the products formed from syngas using alkali promoted MoS2 catalysts, however it is not limited to these types of catalysts. During higher alcohol synthesis not only the wanted short alcohols (similar to C-2-C-5) are produced, but also a great number of other products in smaller or greater amounts, they are mainly short hydrocarbons (olefins, paraffins, branched, non-branched), aldehydes, esters and ketones as well as CO2, H2O. Trace amounts of sulfur-containing compounds can also be found in the product effluent when sulfur-containing catalysts are used and/or sulfur-containing syngas is feed. In the presented GC system, most of them can be separated and analyzed within 60 min without the use of cryogenic cooling. Previously, product analysis in "higher alcohol synthesis" has in most cases been carried out partly on-line and partly off-line, where the light gases (gases at room temp) are analyzed on-line and liquid products (liquid at room temp) are collected in a trap for later analysis off-line. This method suffers from many drawbacks compared to a complete on-line GC system. In this paper an on-line system using an Agilent 7890 gas chromatograph equipped with two flame ionization detectors (FID) and a thermal conductivity detector (TCD), together with an Agilent 6890 with sulfur chemiluminescence dual plasma detector (SCD) is presented. A two-dimensional GC system with Deans switch (heart-cut) and two capillary columns (HP-FFAP and HP-Al2O3) was used for analysis of the organic products on the FIDs. Light inorganic gases (H-2, CO, CO2, N-2) and methane were separated on packed columns and quantified with the TCD. The "sulfur GC" was optimized for on-line trace level sulfur analysis in hydrocarbon matrices and used to understand to which degree sulfur is released from the catalyst and incorporated into the liquid product, and if so in which form. The method provides excellent quantitative measurements with a carbon material balance near 99.5% (carbon in/carbon out) for individual measurement points.

  • 7.
    Björkholm, Eva
    et al.
    Arbetsmiljöinstitutet.
    Hultman, Annika
    Arbetsmiljöinstitutet.
    Rudling, Jan
    Arbetsmiljöinstitutet.
    Determination of chlorine and chlorine dioxide in workplace air by impinger collection and ion-chromatographic analysis1988In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, no 457, p. 409-414Article in journal (Refereed)
  • 8.
    Burman, Lina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Höglund, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Solid-Phase Microextraction for Qualitative and Quantitative Determination of Migrated Degradation Products of Antioxidants in an Organic Aqueous Solution2005In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1080, no 2, p. 107-116Article in journal (Refereed)
    Abstract [en]

     Low molecular weight aromatic substances may migrate out from plastic packaging to their contents, especially if they consist of organic aqueous solutions or oils. It is, therefore, extremely important to be able to identify and quantify any migrated substances in such solutions, even at very low concentrations. We have in this work investigated and evaluated the use of solid-phase microextraction for the specific task of extraction from an organic aqueous solution such as a simulated pharmaceutical solution consisting of 10 vol.% ethanol in water. The goal was furthermore to investigate the possibility of simultaneously identifying and quantifying the substances in spite of differences in their chemical structures. Methods were developed and evaluated for extraction both with direct sampling and with headspace sampling. Difficulties appeared due to the ethanol in the solution and the minute amounts of substances present. We have shown that a simultaneous quantification of migrated low molecular weight degradation products of antioxidants using only one fibre is possible if the extraction method and temperature are adjusted in relation to the concentration levels of the analytes. Comparions were made with solid-phase extraction.

  • 9. Collen, A.
    et al.
    Penttila, M.
    Stalbrand, H.
    Tjerneld, F.
    Veide, Andres
    KTH, Superseded Departments, Biotechnology.
    Extraction of endoglucanase I (Cel7B) fusion proteins from Trichoderma reesei culture filtrate in a poly(ethylene glycol)phosphate aqueous two-phase system2002In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 943, no 1, p. 55-62Article in journal (Refereed)
    Abstract [en]

    Endoglucanases (EGI) (endo-1,4-beta-D-glucan-4-glucanohydrolase, EC 3.2.1.4, Cel7B) of Trichoderma reesei are industrially important enzymes. Thus, there is a great need for development of a primary recovery method suitable for large-scale utilization. In this study we present a concept applicable for large-scale purification of an EGI fusion protein by one-step extraction in a poly(ethylene glycol) PEG-sodium/potassium phosphate aqueous two-phase system. EGI is a two-module enzyme composed of an N-terminal catalytic module and a C-terminal cellulose binding module (CBM) separated by a glycosylated linker region. Partitioning of six different EGI constructs, containing the C-terminal extensions (WP)(2), (WP)(4) or the amphiphilic protein hydrophobin I (HFB) of T. reesei instead of the CBM were studied to evaluate if any of the fusions could improve the partition coefficient sufficiently to be suitable for large-scale production. All constructs showed improved partitioning in comparison to full length EGI. The (WP)(4) extensions resulted in 26- to 60-fold improvement of partition coefficient. Consequently, a relative minor change in amino acid sequence on the two-module protein EGI improved the partition coefficient significantly in the PEG 4000-sodium/potassium phosphate system. The addition of HFBI to EGI clearly enhanced the partition coefficient (K=1.2) in comparison to full-length EGI (K=0.035). Partitioning of the construct with (WP)(4) fused to the catalytic module and a short sequence of the linker [EGI(core-P5)(WP)(4)] resulted in the highest partition coefficient (K=54) and a yield of 98% in the PEG phase. Gel electrophoresis showed that the construct with the (WP)(4) tag attached after a penta-proline linker could be purified from the other bulk proteins by only a single-step separation in the PEG 4000-sodium/potassium phosphate system. This is a major improvement in comparison with the previously studied model (ethylene oxide-propylene oxide)-dextran system. Hence, this construct will be suitable for further optimization of the extraction of the enzyme in a PEG 4000-sodium/potassium phosphate system from culture filtrate.

  • 10. EMMER, Åsa
    et al.
    JANSSON, M
    ROERAADE, J
    IMPROVED CAPILLARY ZONE ELECTROPHORETIC SEPARATION OF BASIC-PROTEINS, USING A FLUOROSURFACTANT BUFFER ADDITIVE1991In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 547, no 1-2, p. 544-550Article in journal (Refereed)
  • 11. Emmer, Åsa
    et al.
    JANSSON, M
    ROERAADE, J
    SEPARATION OF PIG-LIVER ESTERASE ISOENZYMES AND SUBUNITS BY CAPILLARY ZONE ELECTROPHORESIS IN THE PRESENCE OF FLUORINATED SURFACTANTS1994In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 672, no 1-2, p. 231-236Article in journal (Refereed)
  • 12. Emmer, Åsa
    et al.
    ROERAADE, J
    CAPILLARY ELECTROPHORESIS, COMBINED WITH AN ONLINE MICRO POSTCOLUMN ENZYME ASSAY1994In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 662, no 2, p. 375-381Article in journal (Refereed)
  • 13. Gonzalez, Nelida J. D.
    et al.
    Borg-Karlson, Anna-Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Pettersson Redeby, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Noziere, Barbara
    Krejci, Radovan
    Pei, Yuxin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dommen, Josef
    Prevot, Andre S. H.
    New method for resolving the enantiomeric composition of 2-methyltetrols in atmospheric organic aerosols2011In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 51, p. 9288-9294Article in journal (Refereed)
    Abstract [en]

    In order to facilitate the determination of the primary and secondary origin of atmospheric organic aerosols, a novel method involving chiral capillary gas chromatography coupled with mass spectrometry has been developed and validated. The method was focused on the analysis of 2-methylerythritol and 2-methylthreitol, considered to be tracers of secondary organic aerosols from the oxidation of atmospheric isoprene. The method was validated by performing various tests using authentic standards, including pure enantiomeric standards. The result showed that the analytical method itself does not affect the enantiomeric composition of the samples analyzed. The method was applied on atmospheric aerosols from a boreal forest collected in Aspvreten, Sweden and on laboratory samples obtained from liquid phase oxidation of isoprene and smog chamber experiments. Aerosol samples contained one enantiomer of 2-methylerythritol in significantly larger quantities than the others. In contrast, the liquid-phase oxidation of isoprene and its gas-phase oxidation in the smog chamber produced all enantiomers in equal quantities. The results obtained where the enantiomer fraction, EF, is larger than 0.50 suggest that 2-methyltetrols in atmospheric aerosols may also have biological origin. Information about the differences between enantiomer fractions obtained using this method brings new insights in the area of atmospheric aerosols.

  • 14.
    Groning, Mikael
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Hakkarainen, Minna
    KTH, Superseded Departments, Polymer Technology.
    Multiple headspace solid-phase microextraction of 2-cyclopentyl-cyclopentanone in polyamide 6.6: possibilities and limitations in the headspace analysis of solid hydrogen-bonding matrices2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1052, no 02-jan, p. 61-68Article in journal (Refereed)
    Abstract [en]

    The interactions between a polar analyte, 2-cyclopentyl-cyclopentanone, and a solid polar matrix, polyamide 6.6, during multiple headspace solid-phase microextraction (MHS-SPME) were studied. Strong hydrogen bonding between the analyte and the matrix was observed and shown to cause slow migration and adsorption of the analyte. These matrix effects led to erroneous quantitation despite the use of multiple headspace extraction. Addition of water disrupted the hydrogen bonding between the analyte and the matrix and a valid quantitation was achieved. The addition of water also increased the sensitivity and allowed the identification of 2,5-bis(cyclopentyl)-1-cyclopentanone. The amount of 2-cyclopentyl-cyclopentanone in five different polyamide 6.6 samples was measured using the developed multiple headspace solid-phase microextraction method with water-displacer. The measured concentrations were in the range of 1.44-15.61 mug/g. These concentrations were up to 30% higher than the concentrations measured after microwave-assisted extraction (MAE), which indicates incomplete recovery by MAE. The use of water as a displacer eliminated the matrix effects and complete recovery of the analyte was achieved by MHS-SPME.

  • 15.
    Gräslund, Torbjörn
    et al.
    KTH, Superseded Departments, Biochemistry and Biotechnology.
    Ehn, Maria
    KTH, Superseded Departments, Biochemistry and Biotechnology.
    Gunnel, Lundin
    KTH, Superseded Departments, Biochemistry and Biotechnology.
    Hedhammar, My
    KTH, Superseded Departments, Biochemistry and Biotechnology.
    Uhlén, Mathias
    KTH, Superseded Departments, Biochemistry and Biotechnology.
    Nygren, Per-Åke
    KTH, Superseded Departments, Biochemistry and Biotechnology.
    Hober, Sophia
    KTH, School of Biotechnology (BIO), Proteomics.
    Strategy for highly selective ion-exchange capture using a charge-polarizing fusion partner2002In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 942, no 1-2, p. 157-166Article in journal (Refereed)
    Abstract [en]

    To achieve efficient recovery of recombinantly produced target proteins using cation-exchange chromatography, a novel basic protein domain is used as a purification handle. The proteolytic instability usually encountered for basic peptide tags is avoided by the use of a highly constrained α-helical domain based on staphylococcal protein A into which positively charged amino acids have been introduced. Here we show that this domain, consisting of 58 amino acids with a calculated isoelectric point (pI) of 10.5, can be used to efficiently capture different fused target proteins, such as a bacterial DNA polymerase (Klenow fragment), a viral protease (3C) and a fungal lipase (Cutinase). In contrast to standard cation-exchange chromatography, efficient capture can be achieved also at a pH value higher than the pI of the fusion protein, demonstrated here by Zbasic-Klenow polymerase (pI≈5.8) and ZZ-Cutinase-Zbasic (pI≈7.2) both purified at a pH of 7.5. These results show that the Zbasic domain is able to confer a regional concentration of positive charge on the fusion protein even at a relatively high pH. Hence, the data suggest that this domain could be used for highly efficient and selective capture of target proteins at conditions where most host-cell proteins do not bind to the chromatographic resin. The obtained purity after this one-step procedure suggests that the strategy could be an alternative to standard affinity chromatography. Methods for site-specific proteolysis of the fusion proteins to release native target proteins are also discussed.

  • 16. Gröning, M.
    et al.
    Hakkarainen, Minna
    KTH, Superseded Departments, Polymer Technology.
    Headspace solid-phase microextraction - a tool for new insights into the long-term thermo-oxidation mechanism of polyamide 6.62001In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 932, no 02-jan, p. 1-11Article in journal (Refereed)
    Abstract [en]

    Low-molecular-mass products formed. during thermo-oxidation of polyamide 6.6 at 100 degreesC were extracted by headspace solid-phase microextraction and identified by GC-MS. A total of 18 degradation products of polyamide 6.6 were identified. In addition some low-molecular-mass products originating from the lubricants were detected. The identified degradation products were categorized into four groups where compounds within each group contain the same structural feature. In groups A, B and C several new thermo-oxidation products of polyamide 6.6 were identified including cyclic imides, pyridines and structural fragments from the original polyamide chain. 1-Pentyl-2,5-pyrrolidinedione (pentylsuccinimide) showed the largest increase in abundance during oxidation. The cyclopentanones in group D were already present in the un-aged material. Their amounts decreased during ageing and they are thus not formed during thermo-oxidation of polyamide 6.6 at 100 degreesC. The identified thermo-oxidation products can be formed as a result of extensive oxidation of the hexamethylenediamine unit in the polyamide backbone. The degradation products pattern shows that the long-term thermo-oxidative degradation, just like thermal degradation and photo-oxidation of polyamide 6.6, starts at the N-vicinal methylene groups.

  • 17.
    Gröning, Mikael
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Hakkarainen, Minna
    KTH, Superseded Departments, Polymer Technology.
    Correlation between emitted and total amount of 2-cyclopentyl-cyclopentanone in polyamide 6.6 allows rapid assessment by HS and HS-SPME under non-equilibrium conditions2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1052, no 02-jan, p. 151-159Article in journal (Refereed)
    Abstract [en]

    A correlation was found between the emitted and total amount of 2-cyclopentyl-cyclopentanone in polyamide 6.6. The emitted amounts were measured by GC-MS after headspace (HS) or headspace solid-phase microextraction (HS-SPME) and the total content was determined after microwave-assisted extraction (MAE). The correlation was valid also under non-equilibrium conditions, which allows rapid assessment of 2-cyclopentyl-cyclopentanone content in polyamide 6.6 by headspace techniques. The incubation time needed for non-equilibrium headspace analysis could be reduced from 5 h to 45 min if the PA66 granules were milled to powder prior to extraction. However, to reach equilibrium between the analyte in the solid sample and the headspace still required 12 h of incubation at 80degreesC. The long incubation time is explained by slow diffusion rate due to the strong hydrogen bonding between analyte and matrix and the relatively high crystallinity of polyamide 6.6. The headspace extraction profile showed several equilibrium-like patterns that are easily mistaken for the real equilibrium.

  • 18.
    Hakkarainen, Minna
    KTH, Superseded Departments, Polymer Technology.
    Qualitative and quantitative solid-phase microextraction gas chromatographic-mass spectrometric determination of the low-molecular-mass compounds released from poly(vinyl chloride)/polycaprolactone-polycarbonate during ageing2003In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1010, no 1, p. 9-16Article in journal (Refereed)
    Abstract [en]

    A solid-phase microextraction (SPME) method was developed to quantitatively determine the amount of 6-hydroxyhexanoic acid in aqueous solutions. The SPME method in combination with GC-MS was then applied to identify and quantify the low-molecular-mass compounds migrating from a new poly(vinyl chloride) (PVC) material, PVC/polycaprolactone-polycarbonate (PCL-PC) during ageing in water. It was shown that only a small amount of 6-hydroxyhexanoic acid, the final hydrolysis product of PCL-PC, migrated from the blend during ageing at 37 and 70 degreesC. If, however, the temperature was raised to 100 degreesC rapid hydrolysis of PCL-PC resulted. In addition to 6-hydroxyhexanoic acid, 6-hydroxyhexanoic acid dimer, caprolactone, different carboxylic acids, acetophenone and phenol were identified. SPME-GC-MS was also applied to monitor the low-molecular-mass compounds migrating from the PVC/PCL-PC blend during thermo-oxidation.

  • 19.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Solid-phase extraction and subsequent gas-chromatography-mass spectrometry analysis for identification of complex mixtures of degradation products in starch-based polymers1996In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 741, p. 251-263Article in journal (Refereed)
  • 20. Hansson, E.
    et al.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Multiple headspace single-drop microextraction - a new technique for quantitative determination of styrene in polystyrene2006In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1102, no 1-2, p. 91-95Article in journal (Refereed)
    Abstract [en]

    Single-drop microextraction (SDME), an emerging miniaturised extraction technique, was for the first time combined with multiple headspace extraction (MHE) to enable the quantitative determination of volatiles in solid matrixes by SDME technique. The concept of multiple headspace single-drop microextraction (MHS-SDME) was then applied for quantitative determination of styrene in polystyrene (PS) samples. Good linearity for the multiple headspace extraction was obtained when the migration of styrene was facilitated by grinding the samples and incubating them for 1 h at 150 degrees C prior the first extraction. Two microlitres of butyl acetate was used as the single-drop microextraction solvent and the extraction time was 5 min per cycle. The relative standard deviation (RSD) for single-drop microextraction of styrene standard at n = 6 was 7.6%. Linearity was shown for styrene concentrations between 0.005 and 0.75 mu g/ml (R-2 = 0.999). This corresponds to total amount of styrene between 0.1 and 15 mu g. The limit of quantitation for styrene standard at S/N 10 was 0.005 mu g/ml. The developed method was validated against and showed good agreement with an earlier reported dissolution-precipitation method.

  • 21.
    Hedhammar, My
    et al.
    KTH, School of Biotechnology (BIO), Proteomics.
    Hober, Sophia
    KTH, School of Biotechnology (BIO), Proteomics.
    Z(basic) - A novel purification tag for efficient protein recovery2007In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1161, no 1-2, p. 22-28Article in journal (Refereed)
    Abstract [en]

    A positively charged protein domain, Z(basic) can be used as a general purification tag to achieve efficient recovery of recombinantly produced target proteins using cation-exchange chromatography. To construct a protein domain usable for ion-exchange chromatography, the surface of protein Z was engineered to be highly charged, which allowed for selective capture of target proteins on a cation-exchanger at physiological pH values. Interestingly, the novel domain, denoted Z(basic) was shown to be selective also under denaturing conditions and could preferably be used for purification of proteins solubilised from inclusion bodies. Moreover, a flexible process for solid-phase refolding was developed, using Z(basic) as a reversible linker to the cation-exchanger resin. This procedure has the inherited advantage of combining purification and refolding into a single step and still enabling elution of a concentrated product in a suitable buffer. This article summarizes development and use of the Z(basic), tag in small and pilot-plant-scale downstream processing.

  • 22.
    Hult, E L
    et al.
    KTH, Superseded Departments, Chemistry.
    Emmer, Åsa
    KTH, Superseded Departments, Chemistry.
    Roeraade, Johan
    KTH, Superseded Departments, Chemistry.
    Capillary electrophoretic separation of acidic and basic proteins in the presence of cationic and anionic fluorosurfactants1997In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 757, no 1-2, p. 255-262Article in journal (Refereed)
  • 23. JANSSON, M
    et al.
    EMMER, ÅSA
    ROERAADE, J
    LINDBERG, U
    HOK, B
    MICROVIALS ON A SILICON-WAFER FOR SAMPLE INTRODUCTION IN CAPILLARY ELECTROPHORESIS1992In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 626, no 2, p. 310-314Article in journal (Refereed)
  • 24.
    Karlsson, S.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Banhidi, Z.G.
    Albertsson, A-C.
    Detection by high-performance liquid chromatography of polyamines formed by clostridial putrefaction of caseins1988In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 442, p. 267-277Article in journal (Refereed)
  • 25.
    Karlsson, S.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Sares, C.
    Renstad, R,
    Albertsson, A-C.
    Gas chromatographic, liquid chromatographic and gas chromatographic-mass spectrometric identification of degradation products in accelerated aged microbial polyhydroxyalkanoates1994In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 669, no 1-2, p. 97-102Article in journal (Refereed)
  • 26.
    Karlsson, Sigbritt
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Identification by headspace gas chromatography-mass spectrometry of in vitro degradation products of homo-and copolymers of L- and D,L-lactide and 1,5-dioxepan-2-one1994In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 688, p. 251-259Article in journal (Refereed)
  • 27. Kepka, C.
    et al.
    Collet, E.
    Roos, F.
    Tjerneld, F.
    Veide, Andres
    KTH, School of Biotechnology (BIO), Bioprocess Technology.
    Two-step recovery process for tryptophan tagged cutinase: Interfacing aqueous two-phase extraction and hydrophobic interaction chromatography2005In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1075, no 02-jan, p. 33-41Article in journal (Refereed)
    Abstract [en]

    In this work, the interfacing of a poly(ethylene glycol) (PEG)-phosphate aqueous two-phase system with hydrophobic interaction chromatography (HIC) for primary recovery of an intracellular protein was evaluated. As a model protein, a recombinant cutinase furnished with a tryptophan-proline (WP) peptide tag was used and produced intracellularly in Escherichia coli (E. coli). E. coli cell homogenate was partitioned in a two-phase system and the top phase yield, concentration and purity of the tagged ZZ-cutinase-(WP)(4) was evaluated as function of polymer sizes, system pH and phase volume ratio. The partition behaviour of cell debris, total protein and endotoxin was also monitored. In the HIC part, the chromatographic yield and purity was investigated with respect to ligand hydrophobicity, dilution of loaded top phase and elution conditions. Based on the results, a recovery process was demonstrated where a PEG 1500-K-Na phosphate salt aqueous two-phase system was interfaced with a HIC column. The interfacing was facilitated by the Trp-tagged peptide. The tagged ZZ-cutinase-(WP)4 was obtained in a PEG-free phase and purified to > 95% purity according to silver stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels with a total yield of 83% during the two-step recovery process. © 2005 Elsevier B.V. All rights reserved.

  • 28.
    Kloskowski, Adam
    et al.
    KTH, Superseded Departments, Chemistry.
    Pettersson, Johan
    KTH, Superseded Departments, Chemistry.
    Roeraade, Johan
    KTH, Superseded Departments, Chemistry.
    Thick film traps with an irregular film: Preparation and evaluation2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1035, no 2, p. 159-165Article in journal (Refereed)
    Abstract [en]

    A new method for preparation of sorbent-based ultra-thick film traps for concentration of trace volatile components from gaseous matrices is described. The procedure is based on blowing a prepolymer (polydimethylsiloxane) through a capillary tube, forming an irregular film of stationary phase. Subsequently, the prepolymer is immobilized in a few seconds by heating to 200 °C. Evaluation of the performance of the new traps showed that the loss of efficiency, compared to regular smooth film traps is only on the order of 20–30%. In terms of breakthrough volume, this loss in performance is rather insignificant. The technology is extremely simple and allows a rapid and cheap production of a large number of ultra-thick film traps, even in non-specialized laboratories. The method can be applied to any type of cross-linkable stationary phase, thereby expanding the scope of sorbent-based trapping and preconcentration concept. Many applications are anticipated in trace and ultra-trace analysis in a wide range of fields, such as environmental chemistry, polymers, food and process analysis.

  • 29. Liapis, A. I.
    et al.
    Grimes, B. A.
    Lacki, K.
    Neretnieks, Ivars
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Modeling and analysis of the dynamic behavior of mechanisms that result in the development of inner radial humps in the concentration of a single adsorbate in the adsorbed phase of porous adsorbent particles observed in confocal scanning laser microscopy experiments: diffusional mass transfer and adsorption in the presence of an electrical double layer2001In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 921, no 2, p. 135-145Article in journal (Refereed)
    Abstract [en]

    A theoretical model for adsorption of a single charged adsorbate that accounts for the presence of an electrical double layer in the pores of adsorbent particles is constructed and solved. The dynamic behavior of the mechanisms of the model can result in the development of inner radial humps (concentration rings) in the concentration of a single charged analyte (adsorbate) in the adsorbed phase of porous adsorbent particles. The results of the present work demonstrate the implication of the concept regarding the effect of the presence of an electrical double layer in the pores of adsorbent particles and the induced interactions between the electrostatic potential distribution and the mechanisms of mass transport of the species by diffusion, electrophoretic migration, and adsorption. Furthermore, the mechanisms of the model could explain qualitatively the development of the concentration ring (hump) observed in confocal scanning laser microscopy experiments.

  • 30.
    Lindström, Annika
    et al.
    KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology.
    Hakkarainen, Minna
    KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology.
    Development of a solid-phase extraction method for simultaneous extraction of adipic acid, succinic acid and 1,4-butanediol formed during hydrolysis of poly(butylene adipate) and poly(butylene succinate2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1022, no 1-2, p. 171-177Article in journal (Refereed)
    Abstract [en]

    A solid-phase extraction (SPE) method was developed for the simultaneous extraction of dicarboxylic acids and diols formed during hydrolysis of poly(butylene succinate), PBS, and poly(butylene adipate), PBA. Four commercial non-polar SPE columns, three silica based: C-8, C-18, C-18 (EC), and one resin based: ENV+, were tested for the extraction of succinic acid, adipic acid and 1,4-butanediol, the expected final hydrolysis products of PBS and PBA. ENV+ resin was chosen as a solid-phase, because it displayed the best extraction efficiency for 1,4-butanediol and succinic acid. Linear range for the extracted analytes was 1-500 ng/mul for adipic acid and 2-500 ng/mul for 1,4-butanediol and succinic acid. Detection and quantification limits for the analytes were between 1-2 and 2-7 ng/mul, respectively, and relative standard deviations were between 3 and 7%. Good repeatability and low detection limits made the developed SPE method and subsequent gas chromatography-mass spectrometry (GC-MS) analysis a sensitive tool for identification and quantification of hydrolysis products at early stages of degradation.

  • 31. Liu, Jun
    et al.
    Kisonen, Victor
    Willfor, Stefan
    Xu, Chunlin
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience.
    Profiling the substitution pattern of xyloglucan derivatives by integrated enzymatic hydrolysis, hydrophilic-interaction liquid chromatography and mass spectrometry2016In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1463, p. 110-120Article in journal (Refereed)
    Abstract [en]

    Plant polysaccharides constitute arguably the most complex family of biomacromolecules in terms of the stereochemistry and regiochemistry of their intramolecular linkages. The chemical modification of such polysaccharides introduces an additional level of complexity for structural determinations. We have developed an integrated analytical procedure combining selective enzymatic hydrolysis, hydrophilic interaction liquid chromatography (HILIC), and mass spectrometry (MS) to describe the substitution pattern of xyloglucan (XyG) and its chemo-enzymatic derivatives (cationic, anionic, and benzyl aminated). Enzymatic hydrolysis of XyG derivatives by a xyloglucan-specific endoglucanase (XEG) generates oligosaccharides amenable for mass spectrometric identification with distinct structures, based on enzymatic substrate recognition and hydrolytic pattern. Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-ToF-MS) and electrospray ionisation mass spectrometry (ESI-MS) offer qualitative mass profiling of the chemical derivatives. Separation and identification of the complex oligosaccharide profiles released by enzymatic hydrolysis is achieved by hyphenation of hydrophilic interaction liquid chromatography with mass spectrometry (HILIC-ESI-MS). Further fragmentation by tandem mass spectrometry (ESI-MS/MS) in positive mode enables the structural sequencing of modified XyG oligosaccharides and the identification of the substituent position without further derivatisation. This integrated approach can be used to obtain semi-quantitative information of the substitution pattern of hemicellulose derivatives, with fundamental implications for their modification mechanisms and performance.

  • 32. Mhaka, Byron
    et al.
    Cukrowska, Ewa
    Bui, Bernadette Tse Sum
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Haupt, Karsten
    Tutu, Hlanganani
    Chimuka, Luke
    Selective extraction of triazine herbicides from food samples based on a combination of a liquid membrane and molecularly imprinted polymers2009In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, no 40, p. 6796-6801Article in journal (Refereed)
    Abstract [en]

    A selective extraction technique based on the combination of liquid membrane (microporous membrane liquid-liquid extraction) and molecularly imprinted polymers (MIP) was applied to triazines herbicides in food samples. Simazine, atrazine and propazine were extracted from aqueous food samples through the hydrophobic porous membrane that was impregnated with toluene, which also formed part of the acceptor phase. In the acceptor phase, the compounds were re-extracted onto MIP particles. The extraction technique was optimised for the amount of molecularly imprinted polymers particles in the organic acceptor phase, extraction time, and type of organic acceptor solvent and desorption solvent. An extraction time of 90 min and 50 mg of MIP were found to be optimum parameters. Toluene as the acceptor phase was found to give higher triazines binding onto MIP particles compared to hexane and combinations of diethyl ether and hexane. 90% methanol in water was found to be the best desorption solvent compared to acetonitrile, methanol and water. The selectivity of the technique was demonstrated by extracting spiked lettuce and apple extracts where clean chromatograms were obtained compared to liquid membrane extraction alone or to the microporous membrane liquid-liquid extraction - non-imprinted polymer combination. The MIP showed a certain degree of group specificity and the extraction efficiency in lettuce extract was 79% (0.72) for simazine. 98% (1.55) for atrazine and 86% (3.08) for propazine.

  • 33. Mikkonen, Saara
    et al.
    Ekström, Henrik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry. COMSOL AB, Sweden.
    Thormann, Wolfgang
    High-resolution dynamic computer simulation of electrophoresis using a multiphysics software platform2018In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1532, p. 216-222Article in journal (Refereed)
    Abstract [en]

    The modeling and simulation software COMSOL Multiphysics (R) was recently extended with an electrophoretic transport interface. Its performance was investigated by comparison to results obtained using the 1D dynamic electrophoresis simulators GENTRANS and SIMUL5. Simulations of zone electrophoresis, isotachophoresis, isoelectric focusing and of an oscillating electrolyte system were performed. Smooth profiles were essentially identical indicating that the COMSOL electrophoretic transport interface is able to reproduce results of the 1D simulators. Differences in the way the respective numerical schemes handle steep concentration gradients and associated instabilities were observed. The COMSOL electrophoretic transport interface is expected to be useful as a general model for simulations in 1D, 2D or 3D geometries, as well as for simulations combining electrophoresis with other physical phenomena.

  • 34. Nevanen, T. K.
    et al.
    Soderholm, L.
    Kukkonen, K.
    Suortti, T.
    Teerinen, T.
    Linder, M.
    Soderlund, H.
    Teeri, Tuula T.
    KTH, Superseded Departments, Biotechnology.
    Efficient enantioselective separation of drug enantiomers by immobilised antibody fragments2001In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 925, no 02-jan, p. 89-97Article in journal (Refereed)
    Abstract [en]

    There is an increasing need for methods for efficient enantioselective separation and purification of chiral drugs. Genetic engineering provides the means for generating recombinant antibodies exhibiting extremely high specificity for even small molecular mass compounds. Here, recombinant antibody fragments have been generated for the drug diarylalkyltriazole that contains two chiral centres. Immobilised antibody fragments has been used successfully for efficient, step-wise separation of two enantiomers of the drug. Owing to the antibody specificity, one enantiomer came out in the flow-through, while the bound enantiomer could be specifically eluted. One of the antibodies tolerated solvents required both for dissolving the target molecules and for their elution for extended times and was shown to function over multiple cycles of the separation process.

  • 35.
    Pettersson, Johan
    et al.
    KTH, Superseded Departments, Chemistry.
    Aldaeus, Fredrik
    KTH, Superseded Departments, Chemistry.
    Kloskowski, Adam
    KTH, Superseded Departments, Chemistry.
    Roeraade, Johan
    KTH, Superseded Departments, Chemistry.
    Ultra thick film open tubular traps with an increased inner diameter2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1047, no 1, p. 93-99Article in journal (Refereed)
    Abstract [en]

    In this paper, the concept of open tubular traps, coated with a very thick film of polydimethyldisiloxane for enrichment of trace volatile components has been further explored. From theoretical calculations as well as practical experiments it is demonstrated that it can be advantageous to increase the inner diameter of such traps. For a given sampling flow rate and phase ratio, the plate number of the traps is not dependent on the inner diameter, provided that the linear flow velocity remains sufficiently high to offset the effect of axial diffusion. It is shown that this is due to the basic fact that for a given sampling flow rate, the average linear flow velocity in the trap is inversely proportional to the square of the inner diameter of the trap. However, in contrast to chromatographic separations, the linear flow velocity is not important. Under conditions of a constant phase ratio, an increased inner diameter also increases the amount of sorbent in the trap, which is a key parameter for obtaining high breakthrough volumes. Open tubular traps with an expanded inner diameter have very low pressure drop characteristics, which provides the possibility to construct new, simplified sampling systems.

  • 36.
    Pettersson, Johan
    et al.
    KTH, Superseded Departments, Chemistry.
    Kloskowski, Adam
    KTH, Superseded Departments, Chemistry.
    Zaniol, Carlo
    KTH, Superseded Departments, Chemistry.
    Roeraade, Johan
    KTH, Superseded Departments, Chemistry.
    Automated high-capacity sorption probe for extraction of organic compounds in aqueous samples followed by gas chromatographic analysis2004In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1033, no 2, p. 339-347Article in journal (Refereed)
    Abstract [en]

    An automated high-capacity sorption device for GC analysis of ultra trace components has been developed. The scope of the presented technique was to combine the simplicity of solid-phase microextraction (SPME) with the high extraction efficiency of the stir bar sorptive extraction technology. Sorptive extractions of water samples were performed using polydimethylsiloxane (PDMS) rubber tubing (120 μl) mounted onto a glass rod. The sampling procedure was carried out by a robotic autoinjector. Since the setup is fully automated, unattended and precise time-controlled extraction of samples is possible and makes quantitation with non-equilibrium extractions feasible. The sorption probes are easy to exchange, which facilitates off-line/in-field sampling. The system was evaluated with a test mixture of 44 environmentally hazardous compounds. Detection limits were found to be in the sub-ppt region. The performance of the system was demonstrated with the analysis of polycyclic aromatic hydrocarbons in urban snow.

  • 37.
    Pettersson, Johan
    et al.
    KTH, Superseded Departments, Chemistry.
    Roeraade, Johan
    KTH, Superseded Departments, Chemistry.
    Quantitative accuracy in the gas chromatographic analysis of solvent mixtures2003In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 985, no 1-2, p. 21-27Article in journal (Refereed)
    Abstract [en]

    Quantitative accuracy is of great importance in the analysis of bulk mixtures of solvents, particularly when the analysis is related to quality control of very large product volumes like in solvent recovery plants. Serious errors can be made if the effects of density differences between the pure solvents and volume contractions are not properly addressed. In earlier work, the use of an iterative process for correcting such errors has been suggested. However, in the case of volume contractions and mixtures of several solvents, this procedure is difficult to apply. In the present paper, we describe a simple procedure where calibration curves based on mass concentration are utilized. The densities of calibration mixtures of known compositions are determined with a density meter, in order to provide for correction factors caused by volume contractions. Model experiments with mixtures of water, ethanol, acetone and methanol showed a significant improvement in quantitative accuracy, when the suggested calibration strategy was applied.

  • 38.
    Pettersson, Marie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Unelius, Rikard
    Borg-Karlson, Anna-Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Semiochemicals related to the aphid Cinara pillicornis (Hartig) and its host, Picea abies. A method to assign diastereomers of nepetalactone2008In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1180, no 1-2, p. 165-170Article in journal (Refereed)
    Abstract [en]

    Volatiles released by seedlings of Norway spruce infested with the aphid Cinara pilicornis were analyzed using SPME–GC–MS. Among the stress-induced compounds released by the host plant, citronellol, cis–trans-nepetalactone and cis–trans-nepetalactol was found. These compounds originated from the aphids and they were assumed to be pheromone components for this aphid species. To determine the relative stereochemistry of the nepetalactone, a diagnostic method was developed. The method was based on multivariate analysis of tabulated relative intensities of mass fragments of the four nepetalactone diastereomers. In the practical method described, a few pairs of fragments in the mass spectra were compared and, in combination with the Kovat's index, were used to unambiguously identify the relative stereochemistry of the nepetalactone.

  • 39.
    Rudling, Jan
    et al.
    Research Department, National Board of Occupational Safety and Health.
    Björkholm, Eva
    Research Department, National Board of Occupational Safety and Health.
    Irreversibility effects in liquid desorption of organic solvents from activated carbon1987In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 392, p. 239-248Article in journal (Refereed)
  • 40.
    Russom, Aman
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Tooke, Nigel
    Andersson, Helene
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Single nucleotide polymorphism analysis by allele-specific primer extension with real-time bioluminescence detection in a microfluidic device2003In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1014, no 1-2, p. 37-45Article in journal (Refereed)
    Abstract [en]

    A microfluidic approach for rapid bioluminescent real-time detection of single nucleotide polymorphism (SNP) is presented. The method is based on single-step primer extension using pyrosequencing chemistry to monitor nucleotide incorporations in real-time. The method takes advantage of the fact that the reaction kinetics differ between matched and mismatched primer-template configurations. We show here that monitoring the initial reaction in real time accurately scores SNPs by comparing the initial reaction kinetics between matched and mismatched configurations. Thus, no additional treatment is required to improve the sequence specificity of the extension, which has been the case for many allele-specific extension assays. The microfluidic approach was evaluated using four SNPs. Three of the SNPs included primer-template configurations that have been previously reported to be difficult to resolve by allele-specific primer extension. All SNPs investigated were successfully scored. Using the microfluidic device, the volume for the bioluminescent assay was reduced dramatically, thus offering a cost-effective and fast SNP analysis method.

  • 41.
    Steen, Johanna
    et al.
    KTH, School of Biotechnology (BIO), Proteomics.
    Ramström, Margareta
    KTH, School of Biotechnology (BIO), Proteomics.
    Uhlén, Mathias
    KTH, School of Biotechnology (BIO), Proteomics.
    Hober, Sophia
    KTH, School of Biotechnology (BIO), Proteomics.
    Ottosson, Jenny
    KTH, School of Biotechnology (BIO), Proteomics.
    Automated sample preparation method for mass spectrometry analysis on recombinant proteins2009In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1216, no 20, p. 4457-4464Article in journal (Refereed)
    Abstract [en]

    A completely automated procedure for the purification and desalting of proteins with a polyhistidine purification tag prior to mass spectrometry analysis is presented. The system is ideal for rapid quality control and optimization studies and it provides researchers with a straightforward, reliable tool for studies of recombinant proteins. Forty-eight samples can be prepared within 4.5 h and only small cultivation and buffer volumes are needed. In this proof of concept, 19,000-35,000 Da recombinant proteins from both crude and clarified cell lysates were successfully prepared for subsequent analysis by electrospray ionization anti matrix-assisted laser desorption/ionization mass spectrometry as well as by gel electrophoresis.

  • 42. Sullivan, Mitchell A.
    et al.
    Powell, Prudence O.
    Witt, Torsten
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Roura, Eugeni
    Gilbert, Robert G.
    Improving size-exclusion chromatography separation for glycogen2014In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1332, p. 21-29Article in journal (Refereed)
    Abstract [en]

    Glycogen is a hyperbranched glucose polymer comprised of glycogen beta particles, which can also form much larger composite alpha particles. The recent discovery using size-exclusion chromatography (SEC) that fewer, smaller, alpha particles are found in diabetic-mouse liver compared to healthy mice highlights the need to achieve greater accuracy in the size separation methods used to analyze alpha and beta particles. While past studies have used dimethyl sulfoxide as the SEC eluent to analyze the molecular size and structure of native glycogen, an aqueous eluent has not been rigorously tested and compared with dimethyl sulfoxide. The conditions for SEC of pig-liver glycogen, phytoglycogen and oyster glycogen were optimized by comparing two different eluents, aqueous 50 mM NH4NO3/0.02% NaN3 and dimethyl sulfoxide/0.5% LiBr, run through different column materials and pore sizes at various flow rates. The aqueous system gave distinct size separation of alpha- and beta-particle peaks, allowing for a more detailed and quantitative analysis and comparison between liver glycogen samples. This greater resolution has also revealed key differences between the structure of liver glycogen and phytoglycogen.

  • 43.
    Tang, Bing
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Isacsson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Determination of aromatic hydrocarbons in asphalt release agents using headspace solid-phase microextraction and gas chromatography-mass spectrometry2005In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1069, no 2, p. 235-244Article in journal (Refereed)
    Abstract [en]

    The possibility of quantitative analysis of aromatic hydrocarbons in oil-based asphalt release agents was investigated using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). The target analytes studied were benzene, toluene, ethylbenzene, p-, m-, and o-xylene (BTEX) and 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene. Experimental parameters influencing HS-SPME efficiency were studied (equilibration time between sample and headspace and between headspace and SPME fiber, sample amount and sample matrice effects). A HS-SPME method using hexadecane as a surrogate matrice was developed. The detection limit was estimated as 0.03-0.08 ppm (w/w) for the target analytes investigated. Good linearity was observed (R-2 > 0.999) for all calibration curves at high, medium and low concentration level. The repeatability of the method (RSD, relative standard deviation) was found to be less than 10 % (generally less than 5 %) in triplicate samples and approximately 2 % at eight consecutive tests on one and the same sample. The accuracy of the method given by recovery of spiked samples was between 85 and 106 % (generally between 95 and 105 %). The HS-SPME method developed was applied to four commercially available asphalt release agents. External calibration and standard addition approaches were investigated regarding accuracy. The results showed that standard addition generates higher accuracy than external calibration. The contents of target aromatic hydrocarbons in the asphalt release agents studied varied greatly from approximately 0.1-700 ppm. The method described looks promising. and could be a valuable too] for determination of aromatic hydrocarbons in different types of organic matrices.

  • 44.
    Tang, Bing
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Isacsson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
    Determination of aromatic hydrocarbons in bituminous emulsion sealants using headspace solid-phase microextraction and gas chromatography-mass spectrometry2006In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1137, no 1, p. 15-21Article in journal (Refereed)
    Abstract [en]

    The possibility of quantitative determination of aromatic hydrocarbons in bituminous emulsion sealants was investigated using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). The target analytes studied were benzene, toluene, ethylbenzene, p-, m-, and o-xylene (BTEX) as well as 1,3,5- and 1,2,4-trimethylbenzene. Experimental factors influencing HS-SPME efficiency were studied (sample-headspace equilibration time, extraction time and sample matrix effects). A HS-SPME method using surrogate matrix was developed. The detection limit was estimated as approximately 0.1 ppmw for the target analytes investigated. Good linearity was observed (R-2 > 0.997) for all calibration curves obtained. The repeatability of the method (RSD, relative standard deviation) was found less than 10%. The accuracy of the method given by recovery of spiked samples was between 99 and 116%. The HS-SPME method developed was applied to two commercially available bituminous emulsion sealants. External calibration and standard addition approaches were investigated, and statistical paired t-test was performed. The contents of target aromatic hydrocarbons in the sealants studied varied from approximately 0.4 to 150 ppmw. The method developed shows potential as a tool for the determination of aromatic hydrocarbons in emulsified bituminous materials.

  • 45.
    Vilaplana, Francisco
    et al.
    The University of Queensland.
    Gilbert, Robert G.
    The University of Queensland.
    Analytical methodology for multidimensional size/branch-length distributions for branched glucose polymers using off-line 2-dimensional size-exclusion chromatography and enzymatic treatment2011In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 28, p. 4434-4444Article in journal (Refereed)
    Abstract [en]

    Instrumental and procedural optimizations are developed for a new method to obtain 2-dimensional distributions for branched homopolymers based on size and branching. The method uses 2-dimensional off-line size-exclusion chromatography (SEC) and chemical debranching, in this case using debranching enzymes on branched glucose polymers. This treatment, first presented for the 2D weight and number distributions of starch [F. Vilaplana, R.G. Gilbert, Macromolecules 43 (2010) 7321] is applied here to give 2D weight distributions as functions of size and branch length for glycogen, amylose, and native starch containing both amylopectin and amylose. Completely dissolved polysaccharides are first fractionated by size (hydrodynamic volume) using preparative SEC; the collected fractions are then debranched by addition of isoamylase, and the size distributions of the corresponding branches are analyzed for each fraction using analytical SEC with differential refractive index and with multiple-angle laser light scattering detection. Operational parameters have been optimized to provide sufficient separation resolution for each dimension (size of the whole branched macromolecule and size of the resulting branches after debranching) and to minimize degradation. These 2-dimensional distributions bring out new features in the structure of these branched polysaccharides, and offer a useful tool to elucidate relations between biosynthesis, structure, and properties.

  • 46.
    Vilaplana, Francisco
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Patrik
    Eurofins Food and Agro Sweden.
    Ribes-Greus, Amparo
    Instituto de Tecnología de Materiales (ITM), Universidad Politécnica de Valencia.
    Ivarsson, Per
    Eurofins Food and Agro Sweden.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Analysis of brominated flame retardants in styrenic polymers: Comparison of the extraction efficiency of ultrasonication, microwave-assisted extraction and pressurised liquid extraction2008In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1196, no 1-2, p. 139-146Article in journal (Refereed)
    Abstract [en]

    The extraction efficiency of pressurised liquid extraction (PLE), microwave-assisted extraction (MAE), and ultrasonic-assisted extraction (UAE) under different conditions has been compared for the recovery of the most commonly employed brominated flame retardants (BFRs) from styrenic polymeric Matrixes. A HPLC-MS/MS method has been proposed for the simultaneous separation and quantification of tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD) diastereomers, and decabromodiphenyl ether (deca-BDE) in the polymeric extracts. PLE results in complete extraction of TBBPA and HBCD (95-100% recovery), and intermediate recovery Fates for deca-BDE (50%). MAE, on the other hand, gives comparable performance to PLE for HBCD, but lower extraction yields for TBBPA and mainly deca-BDE. Ultrasonication, finally, offers relatively low extraction recoveries (10-50%). The proposed analytical procedures could be used for the effective identification and quantification of BFRs in styrenic plastics and for quality purposes in recycling facilities that deal with styrenic fractions from waste electrical and electronic equipment (WEEE).

  • 47.
    Vilaplana, Francisco
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Martinez-Sanz, Marta
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ribes-Greus, Amparo
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Emission pattern of semi-volatile organic compounds from recycled styrenic polymers using headspace solid-phase microextraction gas chromatography-mass spectrometry2010In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1217, no 3, p. 359-367Article in journal (Refereed)
    Abstract [en]

    The emission of low molecular weight compounds from recycled high-impact polystyrene (HIPS) has been investigated using headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass Spectrometry (GC-MS). Four released target analytes (styrene, benzaldehyde, acetophenone, and 2-phenylpropanal) were selected for the optimisation of the HS-SPME sampling procedure, by analysing operating parameters such as type of SPME fibre (polarity and operating mechanism), particle size, extraction temperature and time. 26 different compounds were identified to be released at different temperatures from recycled HIPS, including residues of polymerisation, oxidated derivates of styrene, and additives. The type of SPME fibre employed in the sampling procedure affected the detection of emitted components. An adsorptive fibre such as carbowax/polydimethylsiloxane (CAR/PDMS fibre) offered good selectivity for both non-polar and polar volatile compounds at lower temperatures: higher temperatures result ill interferences from less-volatile released compounds. An absorptive fibre as polydimethylsiloxane (PDMS) fibre is Suitable for the detection of less-volatile non-polar molecules at higher temperatures. The nature and relative amount of the emitted compounds increased with higher exposure temperature and smaller polymeric particle size. HS-SPME proves to be a suitable technique for screening the emission of semi-volatile organic compounds (SVOCs) from polymeric materials; reliable quantification of the content of target analytes in recycled HIPS is however difficult due to the complex mass-transfer processes involved, matrix effects, and the difficulties in equilibrating the analytical system.

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