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  • 1.
    Adeniyi, Omotayo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Osmanaj, Blerina
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry, University of Prishtina, Prishtina, Republic of Kosovo.
    Manavalan, Gopinathan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Berisha, Avni
    Department of Chemistry, University of Prishtina, Prishtina, Republic of Kosovo.
    Tesfalidet, Solomon
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Reagentless impedimetric immunosensor for monitoring of methotrexate in human blood serum using multiwalled carbon nanotube@polypyrrole/polytyramine film electrode2024In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 268, no Part 1, article id 125316Article in journal (Refereed)
    Abstract [en]

    Ensuring effective monitoring of methotrexate (MTX) levels in the bloodstream of cancer patients undergoing high-dose methotrexate chemotherapy is crucial to prevent potentially harmful side effects. However, the absence of portable analytical devices suitable for point-of-care bedside monitoring has presented a significant obstacle to achieving real-time MTX monitoring. In this study, we developed an impedimetric immunosensor that doesn't require reagents for measuring MTX levels in undiluted human blood serum. This reagentless approach simplifies the assay process, enabling rapid and straightforward MTX quantification. The immunosensor transducer was fabricated by electrodepositing conductive network of porous multiwalled carbon nanotube@polypyrrole/polytyramine on screen-printed gold microchip electrode (SP–Au/MWCNT70@PPy-PTA). Polyclonal anti-MTX antibodies were immobilized on the film, acting as the immunorecognition element. Non-specific binding was prevented by blocking the transducer interface with denatured bovine serum albumin (dBSA) fibrils, resulting in SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA film electrode. When MTX binds to the SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA interface, the film conductance and electron transfer resistance changes. This conductivity attenuation allows for electrochemical impedimetric signal transduction without a redox-probe solution. The electrochemical impedance spectroscopy (EIS) results showed increased charge transfer resistance and phase angle as MTX concentrations increased. The SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA demonstrated high sensitivity, with a linear response from 0.02 to 20.0 μM and a detection limit of 1.93 nM. The detection limit was 50 times lower than the intended safe level of MTX in human serum. The immunosensor exhibited minimal cross-reactivity with endogenous MTX analogs and serum proteins. The SP-Au/MWCNT70@PPy-PTA/anti-MTXAb|dBSA immunosensor presents a simple and rapid method for therapeutic drug monitoring compared to traditional immunoassay systems.

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  • 2.
    Adeniyi, Omotayo
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Osmanaj, Blerina
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry, University of Prishtina, 10000 Prishtina, Kosovo.
    Manavalan, Gopinathan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, 20500, Finland.
    Avni, Berisah
    Department of Chemistry, University of Prishtina, 10000 Prishtina, Kosovo.
    Boily, Jean-Francois
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tesfalidet, Solomon
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Engineering of layered iron vanadate nanostructure for electrocatalysis: simultaneous detection of methotrexate and folinic acid in blood serum2023In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, article id 142538Article in journal (Refereed)
    Abstract [en]

    In this study, nanostructure kazakhstanite-like iron vanadate (FexV3xOy.H2O) was synthesized and calcined at different temperatures (100-800 °C) in a nitrogen atmosphere. The material was used to modify screen-printed carbon electrodes to achieve an electrocatalytic effect on the surface. The relationship between calcination conditions and the catalytic performance of the electrode towards the oxidation of chemotherapeutic drugs, including methotrexate (MTX) and folinic acid (FA), was studied. Various spectroscopic, microscopic, and electrochemical methods were used to characterize the synthesized materials. The results show that calcination induces changes in the electronic structure, nanostructure morphology, electroactive surface area, and electrocatalytic performance of the material. Screen-printed carbon electrode modified with FexV3xOy calcinated at 450 °C (SPC/FexV3xOy-450) was used to develop a voltammetric sensor for the determination of MTX and FA in blood serum. The response of the SPC/FexV3xOy-450 towards the electrooxidation of MTX and FA was the highest in comparison to the bare SPC and SPC/FexV3xOy calcined at other temperatures. The SPC/FexV3xOy-450 exhibited a linear relationship over a wide concentration range: 0.005-200 µM for MTX and 0.05-200 µM for FA. The detection limit was 2.85 nM for MTX and 7.79 nM for FA. Compared to conventional methods, the SPC/FexV3xOy-450 sensor had a short response time (5 min) for simultaneous detection of MTX and FA without signal interferences from coexisting electroactive compounds. The accurate and precise determination of MTX in the presence of FA confirmed the potential clinical applications of SPC/FexV3xOy-450 for therapeutic drug monitoring during chemotherapy.

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  • 3. Ahlgren, Joakim
    et al.
    De Brabandere, Heidi
    Reitzel, Kasper
    Rydin, Emil
    Gogoll, Adolf
    Waldeback, Monica
    Sediment phosphorus extractants for phosphorus-31 nuclear magnetic resonance analysis: A quantitative evaluation2007In: Journal of Environmental Quality, ISSN 0047-2425, E-ISSN 1537-2537, Vol. 36, no 3, p. 892-898Article in journal (Refereed)
    Abstract [en]

    The influence of pre-extractant, extractant, and post-extractant on total extracted amounts of P and organic P compound groups measured with 31 P nuclear magnetic resonance (P-31-NMR) in lacustrine sediment was examined. The main extractants investigated were sodium hydroxide (NaOH) and sodium hydroxide ethylenediaminetetraacetic acid (NaOH-EDTA) with bicarbonate buffered dithionite (BD) or EDTA as pre-extractants. Post extractions were conducted using either NaOH or NaOH-EDTA, depending on the main extractant. Results showed that the most efficient combination of extractants for total P yield was NaOH with EDTA as pre-extractant, yielding almost 50% more than the second best procedure. The P compound groups varying the most between the different extraction procedures were polyphosphates and pyrophosphates. NaOH with BD as pre-extractant was the most efficient combination for these compound groups.

  • 4.
    Ahlgren, Ulf
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Imaging shows insulin-producing cells in diabetes2013In: TrAC. Trends in analytical chemistry, ISSN 0165-9936, E-ISSN 1879-3142, Vol. 44, p. III-IIIArticle in journal (Other (popular science, discussion, etc.))
  • 5.
    Alvarez, Laura
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Cordier, Baptiste
    van Teeffelen, Sven
    Cava, Felipe
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Analysis of Gram-negative Bacteria Peptidoglycan by Ultra-performance Liquid Chromatography2020In: Bio-protocol, E-ISSN 2331-8325, Vol. 10, no 19, article id e3780Article in journal (Refereed)
    Abstract [en]

    Bacteria are surrounded by a protective peptidoglycan cell wall. Provided that this structure and the enzymes involved are the preferred target for our most successful antibiotics, determining its structural and chemical complexity is of the highest interest. Traditionally, high-performance liquid chromatography (HPLC) analyses have been performed, but these methods are very time consuming in terms of sample preparation and chromatographic separation. Here we describe an optimized method for preparation of Gram-negative bacteria peptidoglycan and its subsequent analysis by ultra-performance liquid chromatography (UPLC). The use of UPLC in peptidoglycan analyses provides a dramatic reduction of the sample volume and hands-on time required and, furthermore, permits in-line mass spectrometry (MS) of the UPLC resolved muropeptides, thus facilitating their identification. This method improves our capability to perform high throughput analysis to better understand the cell- wall biology.

  • 6.
    Alvarez, Laura
    et al.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Hernandez, Sara B
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    de Pedro, Miguel A
    Cava, Felipe
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Ultra-sensitive, high-resolution liquid chromatography methods for the high-throughput quantitative analysis of bacterial cell wall chemistry and structure2016In: Bacterial cell wall homeostasis: methods and protocols /edited by Hee-Jeon Hong / [ed] Hee-Jeon Hong, New York: Humana Press, 2016, Vol. 1440, p. 11-27Chapter in book (Refereed)
    Abstract [en]

    High-performance liquid chromatography (HPLC) analysis has been critical for determining the structural and chemical complexity of the cell wall. However this method is very time consuming in terms of sample preparation and chromatographic separation. Here we describe (1) optimized methods for peptidoglycan isolation from both Gram-negative and Gram-positive bacteria that dramatically reduce the sample preparation time, and (2) the application of the fast and highly efficient ultra-performance liquid chromatography (UPLC) technology to muropeptide separation and quantification. The advances in both analytical instrumentation and stationary-phase chemistry have allowed for evolved protocols which cut run time from hours (2-3 h) to minutes (10-20 min), and sample demands by at least one order of magnitude. Furthermore, development of methods based on organic solvents permits in-line mass spectrometry (MS) of the UPLC-resolved muropeptides. Application of these technologies to high-throughput analysis will expedite the better understanding of the cell wall biology.

  • 7.
    Andersson, Patrik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ultraviolet absorption spectra of all 209 polychlorinated biphenyls evaluated by principal component analysis1997In: Fresenius' Journal of Analytical Chemistry, ISSN 0937-0633, E-ISSN 1432-1130, Vol. 357, no 8, p. 1088-1092Article in journal (Refereed)
    Abstract [en]

    The ultraviolet absorption spectra of all 209 polychlorinated biphenyls (PCBs) were recorded in the range 200-300 nm and displayed two important absorption maxima, viz., the main-band, lambda(max) 200-225 nm, and the kappa-band, lambda(max) 245-265 nm. By utilising principal component analysis, substitution related spectral characteristics of the PCBs, underlying the main patterns of the spectra, were examined. Captured in the multivariate evaluation were e.g., the importance of chlorine atoms in ortho positions, determining the intensity and existence of the kappa-band, chlorine substitution in para-para position, and the total number of chlorine atoms. The measured UV-spectra of all 209 polychlorinated biphenyls provide important physico-chemical descriptors for use in future quantitative structure-activity and structure-property relationship (QSAR/QSPR) studies.

  • 8.
    Appelblad, Patrik
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences. Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jonsson, Tobias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Determination of C-21 ketosteroids in serum using trifluoromethanesulfonic acid catalyzed precolumn dansylation and 1,1’-oxalyldiimidazole postcolumn peroxyoxalate chemiluminescence detection1998In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 70, no 23, p. 5002-5009Article in journal (Refereed)
    Abstract [en]

    A new procedure for the quantitation of C-21 ketosteroids using trifluoromethanesulfonic acid-catalyzed precolumn dansylation and coupled column liquid chromatographic separation, followed by postcolumn 1,1‘-oxalyldiimidazole peroxyoxalate chemiluminescence detection is presented. In the simultaneous optimization of chromatographic resolution and chemiluminescence intensity, a coupled column chromatographic system and a stopped-flow system were used. An eluent containing 20 mM phosphate buffer at pH 6.7 accomplished an efficient separation of 3α-hydroxy-5β-pregnan-20-one from a mixture containing 10 C-21 ketosteroids. Phosphate buffer also proved to be the most advantageous, among the six buffers tested, for sensitive detection. Experimental design and multivariate data analysis were used to characterize and optimize the postcolumn reaction chemistry in the chromatographic system. A valid full factorial design with excellent predictability showed that the flow rates for both 1,1‘-oxalyldiimidazole and hydrogen peroxide were the factors most strongly affecting the sensitivity of the system. The theoretical plate numbers were above 11 000 for all 10 dansylated ketosteroids. The 3σ detection limit estimated from 3α-hydroxy-5β-pregnan-20-one calibration curve data was 1.6 pmol (n = 4, 125 μL injected) and spiked serum containing 0−74 pmol of this compound showed overall recoveries of 73 ± 9% (n = 12). Quantitation of 3α-hydroxy-5β-pregnan-20-one was finally carried out on 45 serum samples and the results compared to those from a radioimmunoassay (RIA) method. The data acquired with the procedure described in this work compare well with the results from RIA, which confirms the reliability of the new analytical procedure.

  • 9. Appelblad, Patrik
    et al.
    Jonsson, Tobias
    Jiang, Wen
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fast hydrophilic interaction liquid chromatographic separations on bonded zwitterionic stationary phase2008In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 31, no 9, p. 1529-1536Article in journal (Refereed)
    Abstract [en]

    Separation science is an art of obtaining adequate resolution of the desired compounds in minimum time, and with minimum effort in terms of sample preparation and data evaluation. In LC, where selectivity is a main driving force for separation, the availability of different separation modes capable of operating at high flow rates is a way to make combined optimal use of selectivity, efficiency, and speed. The separation of polar and hydrophilic compounds is problematic in RP LC due to the poor retention. Hydrophilic interaction liquid chromatography (HILIC) is a more straightforward separation mode to address this problem. Herein, it is shown that separations in HILIC mode are equally efficient as for RP, providing a potential for very fast separations on short columns. This is not only facilitated by the low viscosity of the mobile phase compositions used, compared to typical RP eluents, but also due to higher column permeability. To exemplify this, baseline separations of uracil and cytosine are shown in less than 4 s and of Tamiflu® and its main metabolite in less than 40 s, both under isocratic conditions. HILIC must therefore be considered having potential for high throughput purposes, and being an attractive candidate as the second separation dimension in 2-D HPLC.

  • 10. Arshadi, Mehrdad
    et al.
    Nilsson, Calle
    Magnusson, Bengt
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gas chromatography-mass spectrometry determination of the pentafluorobenzoyl derivative of methylhydrazine in false morel (Gyromitra esculenta) as a monitor for the content of the toxin gyromitrin2006In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1125, no 2, p. 229-233Article in journal (Refereed)
    Abstract [en]

    The main toxic compound found in false morel (Gyromitra esculenta) is acetaldehyde-N-methyl-N-formylhydrazone (gyromitrin). This paper describes a method of determining the total hydrazones content based on acid hydrolysis of gyromitrin and other related hydrazones in air-dried false morel followed by derivatisation of methylhydrazine with pentafluorobenzoyl chloride. The derivative, tris-pentafluorobenzoyl methylhydrazine (tris-PFB-MH) is analyzed by gas chromatography–mass spectrometry. The overall precision of the method is better than 10% (relative standard deviation) for 0.5 ng/μl methylhydrazine in solution. The minimum detectable concentration of methylhydrazine (tris-PFB-MH) by this method is estimated to be approximately 12 pg/μl, which is equal to 0.3 μg/g dry matter (DM) of false morel.

  • 11.
    Assefa, Anteneh
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Dept. of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden .
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Klanova, Jana
    Wiberg, Karin
    Tracing the sources of PCDD/Fs in Baltic Sea air by using metals as source markers2018In: Environmental Science: Processes & Impacts, ISSN 2050-7887, E-ISSN 2050-7895, Vol. 20, no 3, p. 544-552Article in journal (Refereed)
    Abstract [en]

    The atmosphere is the major contributor of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the Baltic Sea environment. In this study, we investigated the potential of using metals along with PCDD/Fs as markers of important emission sources of PCDD/Fs in air. The air concentrations of PCDD/F congeners (n = 17), other persistent organic pollutants (n = 8) and metals (n = 16) were determined in summer and winter air using high volume samplers at a rural field station (Aspvreten, Sweden) located close to the Baltic Sea coast. During winter, PCDD/F levels were on average 20 times higher than in summer (5.1 +/- 5.8 fg toxicity equivalents (TEQ) m-3 and 0.26 +/- 0.18 fg TEQ m-3, respectively) mostly due to a higher fraction of PCDFs. The increased levels of PCDD/Fs were pronounced mainly in air masses that had travelled from southern (S) and eastern (E) compass sectors. A principal component analysis (PCA) of metal levels in Scots pine (Pinus sylvestris) needles sampled to reflect various air emission source types helped to identify potential marker metals for selected known atmospheric emission sources of PCDD/Fs and to rank among the candidate source types. Brown coal burning, domestic burning and heavy oil burning appeared to be the source types that contribute most of the PCDD/Fs in Baltic Sea air. The current study demonstrates a successful approach for source tracing of PCDD/Fs in air, where integrated indices from seasonal and spatial patterns of PCDD/Fs as well as metal source markers were used to trace and rank sources.

  • 12. Avagyan, Rozanna
    et al.
    Nyström, Robin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boman, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Westerholm, Roger
    Determination of hydroxylated polycyclic aromatic hydrocarbons by HPLC-photoionization tandem mass spectrometry in wood smoke particles and soil samples2015In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 407, no 16, p. 4523-4534Article in journal (Refereed)
    Abstract [en]

    A simple and fast method for analysis of hydroxylated polycyclic aromatic hydrocarbons using pressurized liquid extraction and high performance liquid chromatography utilizing photoionization tandem mass spectrometry was developed. Simultaneous separation and determination of nine hydroxylated polycyclic aromatic hydrocarbons and two hydroxy biphenyls could be performed in negative mode with a run time of 12 min, including equilibration in 5 min. The calibration curves were in two concentration ranges; 1-50 ng/mL and 0.01-50 mu g/mL, with coefficients of correlation R (2) > 0.997. The limits of detection and method quantification limits were in the range of 9-56 pg and 5-38 ng/g, respectively. A two-level full factorial experimental design was used for screening of conditions with the highest impact on the extraction. The extraction procedure was automated and suitable for a large number of samples. The extraction recoveries ranged from 70 to 102 % and the matrix effects were between 92 and 104 %. The overall method was demonstrated on wood smoke particles and soil samples with good analytical performance, and five OH-PAHs were determined in the concentration range of 0.19-210 mu g/g. As far as we know, hydroxylated polycyclic aromatic hydrocarbons were determined in wood smoke and soil samples using photoionization mass spectrometry for the first time in this present study. Accordingly, this study shows that high performance liquid chromatography photoionization tandem mass spectrometry can be a good option for the determination of hydroxylated polycyclic aromatic hydrocarbons in complex environmental samples.

  • 13. Axelsson, Sara
    et al.
    Eriksson, Kåre
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Nilsson, Ulrika
    Determination of resin acids during production of wood pellets-a comparison of HPLC/ESI-MS with the GC/FID MDHS 83/2 method2011In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 13, no 10, p. 2940-2945Article in journal (Refereed)
    Abstract [en]

    Resin acids are constituents of natural and technical products of widespread use. Exposure is known to cause health effects in the airways and on the skin. Liquid chromatography/positive ion electrospray-mass spectrometry (HPLC/pos ESI-MS) was investigated for determination of 7-oxodehydroabietic (7-OXO), dehydroabietic (DHAA) and abietic acid (AA) in wood dust-containing air samples as a derivatisation-free alternative to the GC/FID HSE method 83/2, developed by the Health and Safety Executive UK. The resin acid 7-OXO was measured as a marker for oxidised resin acids, which are known to be the main contact allergens in colophonium. The found detection limits were 0.42 ng m(-3) for 7-OXO, 5.2 ng m(-3) for DHAA and 9.4 ng m(-3) for AA, respectively, which are considerably lower than with the GC/FID method (24, 115 and 89 ng m(-3)). The two methods correlated well, although consistently and significantly lower concentrations of 7-OXO were detected with LC/MS. The higher concentration of this compound with MDHS 83/2 is suggested to be an artefact from the derivatisation step in the presence of soluble wood dust remains.

  • 14.
    Axner, Ove
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Galbács, Gábor
    University of Szeged, Szeged, Hungary.
    Laser spectrometric techniques in analytical atomic spectrometry2012In: Encyclopedia of analytical chemistry, John Wiley & Sons, Ltd , 2012Chapter in book (Refereed)
    Abstract [en]

    The main purpose of this article is to describe the theory, instrumentation, and analytical performance of laser analytical atomic spectrometry, focusing on absorption, fluorescence, and ionization techniques. The structure of the article is such that it first provides an outline of the theory of light-matter interactions that prevail for each type of technique as well as of the most common modulation techniques, primarily, wavelength modulation (WM). This is followed by a section that covers the most important types of instrumentation used. The article finally provides a detailed discussion on the specific instrumentation, mode of operation, use, performance, and applications (both analytical and diagnostic) of each technique. In terms of laser atomic absorption, the focus of the discussion is on the use of approaches to enhance the detection capability by either reducing the amount of noise (as is done by the wavelength modulation absorption spectrometry (WMAS) technique) or by providing an extended interaction length (giving rise to cavity-enhanced absorption spectrometry (CEAS) techniques in general, and cavity ring-down spectrometry (CRDS) in particular). Laser atomic fluorescence techniques (often referred to as laser-excited atomic fluorescence spectrometry (LEAFS)) as well as laser ionization techniques (termed either laser-enhanced ionization (LEI) or resonance ionization spectrometry (RIS)) are also covered in some detail. It is shown that several of these techniques are capable of detecting a variety of elements in liquid samples down to low picogram per milliliter (pg mL−1) or parts-per-trillion (ppt) concentrations and in low femtogram amounts. Also other properties of the techniques, e.g. selectivity and linear dynamic range (LDR), are in general superior to those of conventional (nonlaser-based techniques).

  • 15.
    Bataineh, Mahmoud
    et al.
    Department of Chemistry, Trent University, ON, Peterborough, Canada.
    Schymanski, Emma L.
    Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Esch-sur-Alzette, Luxembourg.
    Gallampois, Christine M.J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Recent analytical methods for risk assessment of emerging contaminants in ecosystems2021In: Pollution Assessment for Sustainable Practices in Applied Sciences and Engineering, Elsevier, 2021, p. 739-778Chapter in book (Refereed)
    Abstract [en]

    The analysis of emerging contaminants (ECs) remains a dynamic and challenging field because this involves analyzing chemicals with widely varying properties in a large variety of environmental matrices. Usually, concentration levels of ECs are particularly low, such that sensitive and selective analytical methods are required for their analysis. This chapter focuses on five classes of ECs (pharmaceuticals and personal care products, disinfection by-products, perfluorinated compounds, polybrominated diphenyl ethers, and benzotriazoles and dioxane [B and D]) in terms of their occurrence and level of detection. It also highlights the rule of regulatory agencies on the EC detection limit. Sampling techniques used to detect ECs in different environmental matrices are discussed, such as (1) water grab samples from inland and offshore; (2) large-volume solid-phase extraction for water samples; (3) passive samplers (Polar Organic Chemical Integrative Sampler, Chemcatcher, Altesil SR sheet, and semipermeable membrane devices); (4) sediment grab samples (Van Veen and gravity-free fall corer); (5) biota grab samples with different trophic levels (sediment microorganisms, mussels, fish, and mammals; and (6) air passive samplers (inland and/or offshore). In addition, the latest progress is reviewed in sample preparation, extraction, and cleanup.

  • 16. Bergknut, Magnus
    et al.
    Persson, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Skyllberg, Ulf
    Molecular characterization of brominated persistent pollutants using extended X-ray absorption fine structure (EXAFS) spectroscopy2008In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 390, no 3, p. 921-928Article in journal (Refereed)
    Abstract [en]

    X-ray absorption fine structure (EXAFS) spectroscopy spectra were collected for three brominated persistent pollutants: 6-bromo-2,4,5-trichlorophenol (BrTriClP), pentabromophenol (PentaBrP) and 3,3',5,5'-tetrabromobisphenol A (TBBA). The substances were selected to be symmetrical (BrTriClP and TBBA) or asymmetrical (PentaBrP) with respect to the atomic Br positions and to differ in the number of bromine and other halide atoms, as well as their relative positions. The asymmetrical PentaBrP was modelled with special detail as not all bromine atoms have identical coordination environments. The studied substances displayed unique EXAFS spectra, which could be used to determine the molecular structure in fair detail. We conclude that EXAFS spectroscopy is a suitable technique for molecular characterization of the comparatively complex molecules within the class of compounds of brominated organic persistent pollutants. A detailed understanding of the EXAFS spectra of the pure compounds opens up possibilities to study the interactions with soil and sediment matrices by means of EXAFS spectroscopy. Figure Brominated organic persistent pollutants are characterized by EXAFS spectroscopy.

  • 17.
    Björklund, Sofie
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Weidemann, Eva
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå Energi AB, Umeå, Sweden.
    Yeung, Leo W.
    Man-Technology-Environment Research Centre (MTM), School of Science and Technology, Örebro University, Örebro, Sweden.
    Jansson, Stina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Occurrence of per- and polyfluoroalkyl substances and unidentified organofluorine in leachate from waste-to-energy stockpile: a case study2021In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 278, article id 130380Article in journal (Refereed)
    Abstract [en]

    Per- and polyfluoroalkyl substances (PFASs) are a diverse group of chemicals used in consumer products, which will inevitably end up in waste streams. Landfills are widely recognized secondary point sources of PFASs, but other types of waste management sites have received less attention. Therefore, in a case study presented here we investigated releases of PFASs from temporarily stored waste by determining quantities of 34 PFASs in leachate from a Waste-to-Energy stockpile (45 000 ± 2000 tonnes) during five months in 2019. We also measured extractable organofluorine (EOF) to account for PFASs not included in the target list. The mean total concentration of the 34 PFAS (Σ34PFAS) was 211 ± 31 ng/L, and short-chain (C4–C7) perfluorocarboxylic acids (PFCAs) accounted for 56–60% of the total. Moreover, we found that Σ34PFAS only accounted for 12% ± 4% of EOF detected in the leachate. Our results demonstrate that waste stockpiles are previously unexplored sources of PFASs in the environment, and the dominance of short-chain PFCAs is consistent with observed profiles of contaminants in landfill leachates.

  • 18.
    Blum, Kristin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Targeted and untargeted analysis of organic contaminants from on-site sewage treatment facilities: Removal, fate and environmental impact2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    On-site sewage treatment facilities (OSSFs) are widely used all over the world to treat wastewater when large-scale sewage treatment plants (STPs) are not economically feasible. Although there is great awareness that the release of untreated wastewater into the environment can lead to water-related diseases and eutrophication, little is known about organic contaminants and their removal by OSSFs, environmental load and fate. Thus, this PhD thesis aims to improve the knowledge about treatment efficiencies in current OSSFs, the environmental impact and fate of contaminants released from OSSFs, as well as how biochar fortification in sand filter (soil beds) OSSFs might increase removal of these contaminants. State-of-the-art analytical techniques for untargeted and targeted analyses were used and the results evaluated with univariate and multivariate statistics.

    Environmentally-relevant contaminants discharged from OSSFs were identified using untargeted analysis with two-dimensional gas chromatography mass spectrometry (GC×GC-MS) and a MS (NIST) library search in combination with a prioritization strategy based on environmental relevance. A method was successfully developed for the prioritized contaminants using solid phase extraction and GC×GC-MS, and the method was also applicable to untargeted analysis. This method was applied to several studies. The first study compared treatment efficiencies between STP and soil beds and showed that treatment efficiencies are similar or better in soil beds, but the removal among the same type of treatment facilities and contaminants varied considerably. Hydrophilic contaminants were generally inadequately removed in both types of treatment facilities and resulted in effluent levels in the nanogram per liter range.

    Additionally, several prioritized and sometimes badly removed compounds were found to be persistent, mobile, and bioavailable and two additional, untargeted contaminants identified by the NIST library search were potentially mobile. These contaminants were also found far from the main source, a large-scale STP, at Lake Ekoln, which is part of the drinking water reservoir Lake Mälaren, Sweden. The study also showed that two persistent, mobile and bioavailable contaminants were additionally bioaccumulating in perch. Sampling for this study was carried out over several seasons in the catchment of the River Fyris. Parts of this catchment were affected by OSSFs, other parts by STPs. Potential ecotoxicological risks at these sites were similar or higher at those affected by STPs compared to those affected by OSSFs. Mass fluxes per capita were calculated from these levels, which were higher at STP-affected than at OSSF-affected sites in summer and autumn, but not in winter. Possibly, the diffuse OSSF emissions occur at greater average distances from the sampling sites than the STP point emissions, and OSSF-affected sites may consequently be more influenced by fate processes.

    The studies carried out suggested that there is a need to improve current treatment technologies for the removal of hydrophilic contaminants. Thus, the final study of this thesis investigated char-fortified sand filters (soil beds) as potential upgrades for OSSFs using a combination of advanced chemical analysis and quantitative structure-property relationship modeling. Removal efficiencies were calculated from a large variety of contaminants that were identified by untargeted analysis using GC×GC-MS and liquid chromatography ion mobility mass spectrometry as well as library searches (NIST and Agilent libraries). On average, char-fortified sand filters removed contaminants better than sand, partly due to an enhanced removal of several hydrophilic contaminants with heteroatoms. After a two-year runtime, sorption and particularly biodegradation must have contributed to the removal of these compounds.

    Generally, the combination of targeted and untargeted analysis has proven valuable in detecting a large variety of organic contaminants, as well as unexpected ones. The results imply that OSSFs have similar or better removal efficiencies, similar or lower environmental risks and similar or lower mass fluxes per capita, compared to STPs. Biochar fortification can improve the removal of organic contaminants in soil beds, but further research is needed to find technologies that reduce the discharge of all types of organic contaminants.

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  • 19.
    Blum, Kristin M.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University.
    Gallampois, Christine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, Patrik L.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Renman, G.
    Renman, A.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comprehensive assessment of organic contaminant removal from on-site sewage treatment facility effluent by char-fortified filter beds2019In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 361, p. 111-122Article in journal (Other academic)
    Abstract [en]

    The removal of organic contaminants from wastewater using cost-efficient and easily accessible methods have been increasingly studied in recent years. Most studies have focused on municipal sewage treatment plants; however, our study investigated treatment with char-fortified filter beds for on-site sewage treatment facilities (OSSFs). OSSFs are commonly used in rural and semi-urban areas all over the world to treat wastewater to reduce eutrophication and water-related diseases. To screen for a wide range of organic contaminants in order to improve the understanding of wastewater treatment efficiency and molecular properties, samples were taken from an OSSF field study site that used three filter types: sand, char-fortified sand, and char-fortified gas concrete. First, we screened for organic contaminants with state-of-the-art gas chromatography and liquid chromatography mass spectrometry-based targeted and untargeted analysis and then we developed quantitative structure-property relationship models to find the key molecular features responsible for the removal of organic contaminants. We identified 74 compounds, of which 24 were confirmed with reference standards. Amongst these 74 compounds were plasticizers, UV stabilizers, fragrances, pesticides, surfactant and polymer impurities, pharmaceuticals and their metabolites, and many biogenic compounds. Sand filters that are sometimes used as a last treatment step in OSSFs can remove hydrophobic contaminants. The addition of biochar significantly increases the removal of these and a few hydrophilic compounds (Wilcoxon signed-rank test, α = 0.05). Gas concrete did not appear to be suitable for the removal of organic contaminants. This study showed that, besides hydrophobic effects, biodegradation is the most important removal pathway in long-term field applications. However, further improvements are necessary to remove very hydrophilic contaminants as they were not removed with sand and biochar-fortified sand.

  • 20.
    Blum, Kristin M.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gao, Qiuju
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ahrens, L.
    Gros, M.
    Wiberg, K.
    Andersson, Patrik L.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mass fluxes per capita of organic contaminants from on-site sewage treatment facilities2018In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, no 201, p. 864-873Article in journal (Other academic)
    Abstract [en]

    This study is the first attempt to quantify environmental fluxes per capita of organic contaminants discharged from on-site sewage treatment facilities (OSSFs) in affected recipients. Five sites were monitored around the River Fyris in Sweden: three mainly affected by OSSFs and two mainly affected by municipal sewage treatment plants (STPs). Gas chromatography-mass spectrometry was used to determine environmental concentrations of 30 anthropogenic contaminants, including organophosphorus compounds, rubber and plastic additives, UV stabilizers, fragrances, surfactant ingredients and polycyclic aromatic hydrocarbons. Uni- and multivariate statistical analysis of the most frequently detected contaminants showed that median fluxes per capita of tris(1,3-dichloro-2-propyl) phosphate, tris(1-chloro-2-propyl) phosphate, tris(2-chloroethyl) phosphate, and n-butylbenzene sulfonamide were similar at OSSF and STP sites, but the mass fluxes per capita of tris-(2-butoxyethyl) phosphate, 2-(methylthio)benzothiazole, and galaxolide, were significantly lower (~2 to 3-fold) at OSSF sites than at STP sites (Mann-Whitney, α = 0.05). Differences between these sites were larger in samples collected in summer and autumn than in samples collected in winter. Deviations likely originated from differences in treatment technology and distances between source and sampling sites. Further studies are needed to characterize mass fluxes per capita of contaminants in waters that directly receive discharges from OSSFs.

  • 21.
    Bouchet, Sylvain
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Analytical developments for the determination of monomethylmercury complexes with low molecular mass thiols by reverse phase liquid chromatography hyphenated to inductively coupled plasma mass spectrometry2014In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1339, p. 50-58Article in journal (Refereed)
    Abstract [en]

    The behavior of monomethylmercury (MMHg) is markedly influenced by its distribution among complexes with low molecular mass (LMM) thiols but analytical methodologies dedicated to measure such complexes are very scarce up to date. In this work, we selected 15 LMM thiols often encountered in living organisms and/or in the environment and evaluated the separation of the 15 corresponding MMHg-thiol complexes by various high performance liquid chromatography (HPLC) columns. Two C18 (Phenomenex Synergi Hydro-RP and LunaC18(2)), two phenyl (Inertsil Ph 3 and 5 mu m) and one mixed-mode (Restek Ultra IBD) stationary phases were tested for their retention and resolution capacities of the various complexes. The objective was to find simple separation conditions with low organic contents in the mobile phase to provide optimal conditions for detection by inductively coupled plasma mass spectrometry (ICPMS). The 15 complexes were synthesized in solution and characterized by electrospray ionization-mass spectrometry (ESI-MS). The C18 columns tested were either not resolutive enough or too retentive. The 3 pm phenyl stationary phase was able to resolve 10 out of the 15 complexes in less than 25 min, under isocratic conditions. The mixed-mode column was especially effective at separating the most hydrophilic complexes (6 complexes out of the 15), corresponding to the main LMM thiols found in living organisms. The detection limits (DLs) for these two columns were in the low nanomolar range and overall slightly better for the phenyl column. The possibilities offered by such methodology were exemplified by monitoring the time-course concentrations of four MMHg-thiol complexes within a phytoplankton incubation containing MMHg in the presence of an excess of four added thiols. 

  • 22.
    Bratthäll, Tove
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Figueira, Joao
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nording, Malin L.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Influence of divalent cations on the extraction of organic acids in coffee determined by GC-MS and NMR2024In: Heliyon, E-ISSN 2405-8440, Vol. 10, no 5, article id e26625Article in journal (Refereed)
    Abstract [en]

    The perceived flavor of coffee varies depending on the composition of the brewing water, and the influencing mechanisms are poorly understood. To investigate the effect of dissolved divalent cations on the extraction of organic acids in coffee, magnesium and calcium chloride salts were added pre- and post-brew. Citric, malic, lactic and quinic acid were analyzed using gas chromatography – mass spectrometry and nuclear magnetic resonance techniques. At concentrations typically found in drinking water, the salts resulted in limited variation of the acid content, while ten-fold higher salt concentrations produced more pronounced variations. Comparisons between pre- and post-brew additions showed similar acid content in most cases, suggesting that extraction of acids proceeds independent of the water composition. Interactions taking place post-brew may, however, influence the perceived flavor. A scientific basis for water quality recommendations in the coffee industry is long overdue and this work provides experimental and analytical contributions to continued research.

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  • 23.
    Bruce, Stephen J
    et al.
    Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Jonsson, Pär
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Antti, Henrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Cloarec, Olivier
    Technologie Servier, 45000 Orleans, France.
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Marklund, Stefan L
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Moritz, Thomas
    Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Evaluation of a protocol for metabolic profiling studies on human blood plasma by combined ultra-performance liquid chromatography/mass spectrometry: From extraction to data analysis2009In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 372, no 2, p. 237-249Article in journal (Refereed)
    Abstract [en]

    The investigation presented here describes a protocol designed to perform high-throughput metabolic profiling analysis on human blood plasma by ultra-performance liquid chromatography/mass spectrometry (UPLC/MS). To address whether a previous extraction protocol for gas chromatography (GC)/MS-based metabolic profiling of plasma could be used for UPLC/MS-based analysis, the original protocol was compared with similar methods for extraction of low-molecular-weight compounds from plasma via protein precipitation. Differences between extraction methods could be observed, but the previously published extraction method was considered the best. UPLC columns with three different stationary phases (C8, C18, and phenyl) were used in identical experimental runs consisting of a total of 60 injections of extracted male and female plasma samples. The C8 column was determined to be the best for metabolic profiling analysis on plasma. The acquired UPLC/MS data of extracted male and female plasma samples was subjected to principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS–DA). Furthermore, a strategy for compound identification was applied here, demonstrating the strength of high-mass-accuracy time-of-flight (TOF)/MS analysis in metabolic profiling.

  • 24.
    Bui, Nhat Thi Hong
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Polyhydroxyl and Polyphosphorylcholine functionalized Silica for Hydrophilic interaction liquid Chromatography- Synthesis, characterization and application2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on the development of new stationary phases for use in hydrophilic interaction liquid chromatography using TRIS-based and phosphorylcholine typed monomers and porous silica particles as starting substrates. In this thesis, several ways of polymerizing highly hydrophilic mono­mers onto pore surfaces of silica supports are described, based on several “grafting from” schemes. “Controlled/living” radical polymerizations including atom transfer radical polymerization (ATRP) and iniferter-mediated polymerization in conjunction with conventional free radical polymerization are demonstrated to be successful tools for grafting different hydrophilic monomers (polyhydroxyl and phosphorylcholine [meth]acrylamide/acrylates) onto the silica surfaces. Reaction solvents are proven to play an essential role to achieve efficient graft polymerization of activated silica surfaces with these amphiphilic vinylic monomers, which is difficult because of their restricted access to the activated surface in solvents that can be used because of solubility constraints.

    Two tentacle TRIS-based polymer grafted silica, namely TRIS-WAX – TRIS functionality bonded to silica via a C–N–C imine bond and TRIS-Amide – TRIS bonded to silica via an amide bond, prove to be useful as stationary phases for hydrophilic interaction chromatography (HILIC).The TRIS-WAX exhibits a mixed mode hydrophilic partitioning and weak anion exchange (HILIC/WAX) retention mechanism while retention by hydrophilic partitioning is the dominant mechanism on the neutral TRIS-Amide phase which lacks weak anion exchange (WAX) properties. Interestingly, both these phases have selectivities that are radically different from most commercial HILIC stationary phases.

    Finally, a method is demonstrated for synthesizing a stratified (graft-copolymerized) silica material based on N,N′-methylenebisacrylamide and 2-methacryloyloxyethyl phosphorylcholine (MPC) using a “controlled/living” photoiniferter-mediated polymerization from the N,N-diethyldithiocarbamate iniferter moiety immobilized silica surfaces. This polymerization method proves to be successful for graft-blockcopolymerization of different highly hydrophilic monomers onto the activated surfaces of porous silica. In this way, silica surfaces are grafted with a cross-linked amide-based hydrogel, on top of which a tentacle zwitterionic phosphorylcholine-typed layer is synthesized. The resulted material proves to be useful for HILIC separations and possesses different selectivity for the tested organic acids compared to that of commercial ZIC-cHILIC stationary phase.

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  • 25. Butina, Karen
    et al.
    Löffler, Susanne
    Rhen, Mikael
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Department of Microbiology, Tumor and Cell Biology, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden.
    Richter-Dahlfors, Agneta
    Electrochemical sensing of bacteria via secreted redox active compounds using conducting polymers2019In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 297, article id 126703Article in journal (Refereed)
    Abstract [en]

    Bacterial infections and antibiotic resistance represent major global threats to public health. Current diagnostics use culture based assays that are reliable but slow, hence appealing for new rapid methods. Here we describe redox sensing as a novel concept for rapid, label-free detection of bacteria. We utilize a two-electrode poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) based sensor for detection of bacterially secreted redox-active compounds. Using purified redox-active compounds, we show the ability of the sensor to detect and quantify compounds in micromolar concentrations within minutes. When applied for detection and quantification of Salmonella, we show that secreted, low molecular weight redox compounds cause reduction of the PEDOT:PSS electrode. A potential role of redox sensing in infection diagnostics was demonstrated as uropathogenic strains of E. coli., Staphylococcus, Enterococcus, Pseudomonas, Proteus, and Klebsiella spp., major causes of complicated urinary tract infections, were successfully detected in complex media or processed urine. Since numerous bacterial species are capable of extracellular electron transfer, redox sensing may find use as a generic method for bacterial detection with applications in research laboatories, the clinic and industry alike.

  • 26.
    Byström, Emil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Porous polymeric materials for chromatography: Synthesis, functionalization and characterization2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Separation science is heavily reliant on materials to fulfill ever more complicated demands raised by other areas of science, notably the rapidly expanding molecular biosciences and environmental monitoring. The key to successful separations lies in a combination of physical properties and surface chemistry of stationary phases used in liquid chromatographic separation, and this thesis address both aspects of novel separation materials.

    Methods: The thesis accounts for several approaches taken during the course of my graduate studies, and the main approaches have been i) to test a wild-grown variety of published methods for surface treatment of fused silica capillaries, to ascertain firm attachment of polymeric monoliths to the wall of microcolumns prepared in silica conduits; ii) developing a novel porogen scheme for organic monoliths including polymeric porogens and macromonomers; iii) evaluating a mesoporous styrenic monolith for characterization of telomers intended for use in surface modification schemes and; iv) to critically assess the validity of a common shortcut used for estimating the porosity of monoliths prepared in microconduits; and finally v) employing plasma chemistry for activating and subsequently modifying the surface of rigid, monodisperse particles prepared from divinylbenzene.

    Results: The efforts accounted for above have resulted in i) better knowledge of the etching and functionalization parameters that determine attachment of organic monoliths prepared by radical polymerization to the surface of silica; ii) polar methacrylic monoliths with a designed macroporosity that approaches the desired "connected rod" macropore morphology; iii) estab¬lishing the usefulness of monoliths prepared via nitroxide mediated polymerization in gradient polymer elution chromatography; iv) proving that scanning electron microscopy images are of limited value for assessing the macroporous properties of organic monoliths, and that pore measurements on externally polymerized monolith cocktails do not represent the porous properties of the same cocktail polymerized in narrow confinements; and v) showing that plasma bromination can be used as an activation step for rigid divinylbenzene particles to act as grafting handles for epoxy-containing telomers, that can be attached in a sufficiently dense layer and converted into carboxylate cation exchange layer that allows protein separations in fully aqueous eluents.

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  • 27.
    Byström, Emil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Viklund, Camilla
    Merck SeQuant AB, Umeå.
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Differences in porous characteristics of styrenic monoliths prepared by controlled thermal polymerization in molds of varying dimensions2010In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 33, no 2, p. 191-199Article in journal (Refereed)
    Abstract [en]

    Nitroxide-mediated polymerization was used as a model system for preparing styrenic monolithic materials with significant mesopore contents in different mold formats, with the aim of assessing the validity of pore characterization of capillary monoliths by analysis of parallel bulk polymerized precursor solution. Capillary monoliths were prepared in 250 mm id fused silica tubes (quadruplicate samples, in total 17 m), and the batch polymerizations were carried out in parallel in 100 mL microvials and regular 2mL glass vials, both in quintuplicate. The monoliths recovered from the molds were characterized for their meso- and macroporous properties by nitrogen sorptiometry (three repeated runs on each sample), followed by a single analysis by mercury intrusion porosimetry. A total of 14 monolith samples were thus analyzed. A Grubbs’ test identified one regular vial sample as an outlier in the sorptiometric surface area measurements, and data from this sample were consequently excluded from the pore size calculations, which are based on the same nitrogen sorption data, and also from the mercury intrusion data set. The remaining data were subjected to single factor analyses of variance analyses to test if the porous properties of the capillary monoliths were different from those of the bulk monoliths prepared in parallel. Significant differences were found between all three formats both in their meso and macroporous properties. When the dimension was shrunk from conventional vial to capillary size, the specific surface area decreased from 52.274.7 to 34.671.7m2/g. This decrease in specific surface area was accompanied by a significant shift in median diameter of the through-pores, from 31073.9 to 544713 nm. None of these differences was obvious from the scanning electron micrographs that were acquired for each sample type. The common practice of determining the mesopore characteristics from analysis of samples prepared by parallel bulk polymerization and looking for changes in the macropore structure by visual assessment of SEMs are therefore both rather questionable, at least for monoliths of the kind used in this study.

  • 28.
    Bäcklund, Nils
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Brattsand, Göran
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Israelsson, Marlen
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Ragnarsson, Oskar
    Burman, Pia
    Edén Engström, Britt
    Høybye, Charlotte
    Berinder, Katarina
    Wahlberg, Jeanette
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Dahlqvist, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Reference intervals of salivary cortisol and cortisone and their diagnostic accuracy in Cushing's syndrome2020In: European Journal of Endocrinology, ISSN 0804-4643, E-ISSN 1479-683X, Vol. 182, no 6, p. 569-582Article in journal (Refereed)
    Abstract [en]

    Objective: The challenge of diagnosing Cushing's syndrome (CS) calls for high precision biochemical screening. This study aimed to establish robust reference intervals for, and compare the diagnostic accuracy of, salivary cortisol and cortisone in late-night samples and after a low-dose (1 mg) dexamethasone suppression test (DST).

    Design and methods: Saliva samples were collected at 08:00 and 23:00 h, and at 08:00 h, after a DST, from 22 patients with CS and from 155 adult reference subjects. We also collected samples at 20:00 and 22:00 h from 78 of the reference subjects. Salivary cortisol and cortisone were analysed with liquid chromatography-tandem mass spectrometry. The reference intervals were calculated as the 2.5th and 97.5th percentiles of the reference population measurements. Diagnostic accuracies of different tests were compared, based on areas under the receiver-operating characteristic curves.

    Results: The upper reference limits of salivary cortisol and cortisone at 23:00 h were 3.6 nmol/L and 13.5 nmol/L, respectively. Using these reference limits, CS was detected with a sensitivity (95% CI) of 90% (70-99%) and specificity of 96% (91-98%) for cortisol, and a 100% (84-100%) sensitivity and 95% (90-98%) specificity for cortisone. After DST, cortisol and cortisone upper reference limits were 0.79 nmol/L and 3.5 nmol/L, respectively. CS was detected with 95% (75-100%) sensitivity and 96% (92-99%) specificity with cortisol, and 100% (83-100%) sensitivity and 94% (89-97%) specificity with cortisone. No differences in salivary cortisol or cortisone levels were found between samples collected at 22:00 and 23:00 h.

    Conclusion: Salivary cortisol and cortisone in late-night samples and after DST showed high accuracy for diagnosing CS, salivary cortisone being slightly, but significantly better.

  • 29.
    Bäcklund, Nils
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Brattsand, Göran
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Lundstedt, Staffan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Aardal, Elisabeth
    Department of Clinical Chemistry, Linköping University, Linköping, Sweden; Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden.
    Bartuseviciene, Inga
    Department of Clinical Chemistry, Karolinska University Hospital, Stockholm, Sweden.
    Berinder, Katarina
    Department of Molecular Medicine and Surgery, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden; Department of Endocrinology, Karolinska University Hospital, Stockholm, Sweden.
    Höybye, Charlotte
    Department of Molecular Medicine and Surgery, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden; Department of Endocrinology, Karolinska University Hospital, Stockholm, Sweden.
    Burman, Pia
    Department of Endocrinology, Skåne University Hospital, Malmö, Sweden.
    Edén Engström, Britt
    Department of Medical Sciences, Endocrinology and Mineral Metabolism, Uppsala University, Uppsala, Sweden; Department of Endocrinology and Diabetes, Uppsala University Hospital, Uppsala, Sweden.
    Isaksson, Anders
    Department of Clinical Chemistry and Pharmacology, Lund University, Lund, Sweden.
    Blomgren, Anders
    Department of Clinical Chemistry and Pharmacology, Lund University, Lund, Sweden.
    Ragnarsson, Oskar
    Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Wallenberg Center for Molecular and Translational Medicine, University of Gothenburg, Gothenburg, Sweden; Department of Endocrinology, Sahlgrenska University Hospital, Göteborg, Sweden.
    Rüetschi, Ulrika
    Department of Clinical Chemistry, Sahlgrenska University Hospital, Gothenburg, Sweden.
    Wahlberg, Jeanette
    School of Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden; Department of Medicine, Örebro University Hospital, Örebro, Sweden.
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Dahlqvist, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Salivary cortisol and cortisone in diagnosis of Cushing's syndrome: a comparison of six different analytical methods2023In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 61, no 10, p. 1780-1791Article in journal (Refereed)
    Abstract [en]

    Objectives: Salivary cortisol and cortisone at late night and after dexamethasone suppression test (DST) are increasingly used for screening of Cushing’s syndrome (CS). We aimed to establish reference intervals for salivary cortisol and cortisone with three liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques and for salivary cortisol with three immunoassays (IAs), and evaluate their diagnostic accuracy for CS.

    Methods: Salivary samples at 08:00 h, 23:00 h and 08:00 h after a 1-mg DST were collected from a reference population (n=155) and patients with CS (n=22). Sample aliquots were analyzed by three LC-MS/MS and three IA methods. After establishing reference intervals, the upper reference limit (URL) for each method was used to calculate sensitivity and specificity for CS. Diagnostic accuracy was evaluated by comparing ROC curves.

    Results: URLs for salivary cortisol at 23:00 h were similar for the LC-MS/MS methods (3.4–3.9 nmol/L), but varied between IAs: Roche (5.8 nmol/L), Salimetrics (4.3 nmol/L), Cisbio (21.6 nmol/L). Corresponding URLs after DST were 0.7–1.0, and 2.4, 4.0 and 5.4 nmol/L, respectively. Salivary cortisone URLs were 13.5–16.6 nmol/L at 23:00 h and 3.0–3.5 nmol/L at 08:00 h after DST. All methods had ROC AUCs ≥0.96.

    Conclusions: We present robust reference intervals for salivary cortisol and cortisone at 08:00 h, 23:00 h and 08:00 h after DST for several clinically used methods. The similarities between LC-MS/MS methods allows for direct comparison of absolute values. Diagnostic accuracy for CS was high for all salivary cortisol and cortisone LC-MS/MS methods and salivary cortisol IAs evaluated.

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  • 30.
    Cant, David J. H.
    et al.
    National Physical Laboratory, Teddington, UK.
    Pei, Yiwen
    National Physical Laboratory, Teddington, UK.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ramstedt, Madeleine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Marques, Sara S.
    Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal.
    Segundo, Marcela A.
    Department of Chemical Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal.
    Parot, Jeremie
    Department of Biotechnology and Nanomedicine, SINTEF Industry, Trondheim, Norway.
    Molska, Alicja
    Department of Biotechnology and Nanomedicine, SINTEF Industry, Trondheim, Norway.
    Borgos, Sven E.
    Department of Biotechnology and Nanomedicine, SINTEF Industry, Trondheim, Norway.
    Shard, Alexander G.
    National Physical Laboratory, Teddington, UK.
    Minelli, Caterina
    National Physical Laboratory, Teddington, UK.
    Cryo-XPS for surface characterization of nanomedicines2023In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 127, no 39, p. 8220-8227Article in journal (Refereed)
    Abstract [en]

    Nanoparticles used for medical applications commonly possess coatings or surface functionalities intended to provide specific behavior in vivo, for example, the use of PEG to provide stealth properties. Direct, quantitative measurement of the surface chemistry and composition of such systems in a hydrated environment has thus far not been demonstrated, yet such measurements are of great importance for the development of nanomedicine systems. Here we demonstrate the first use of cryo-XPS for the measurement of two PEG-functionalized nanomedicines: a polymeric drug delivery system and a lipid nanoparticle mRNA carrier. The observed differences between cryo-XPS and standard XPS measurements indicate the potential of cryo-XPS for providing quantitative measurements of such nanoparticle systems in hydrated conditions.

  • 31.
    Carlsson, Sofia
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Installation of a hydride generation system coupled to atomic absorption spectrometry in Vientiene, Laos PDR - Determination of arsenic in water samples 2012Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Until now, the possibility for the personnel at the National University of Lao PDR (NUOL) to perform analysis of arsenic in drinking water as well as water used for agriculture has been limited to indication sticks, giving only a vague indication of the presence and levels of arsenic. Due to the lack of adequate and sensitive analytical instruments the levels of arsenic are relatively unknown in Lao People Democratic Republic (Lao PDR). A simple method of analyzing arsenic in water is using atomic absorption spectroscopy (AAS) coupled to a hydride generation system (HG). In support of this project, an HG with an AAS-oven has been delivered and installed at the inorganic lab at NUOL. The system has been optimized and tested and the personnel at the university have been instructed and trained in how to use the system. Sampling and analysis were supposed to be executed although this part of the project encountered many problems and could not be performed in a satisfactory way. Problems mainly came from lack of material, i.e. distilled water, and knowledge as well as monsoon weather conditions making the sampling impossible.

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  • 32.
    Cedergren, Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nordmark, Ulrika
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Determination of water in NIST reference material for mineral oils2000In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 72, no 14, p. 3392-3395Article in journal (Refereed)
    Abstract [en]

    The accuracy of the reference concentrations of moisture in electrical insulating oil RM 8506 and lubricating oil RM 8507 (both of mineral type) and specified by the National institute of Standards and Technology (NIST) as containing 39.7 and 76.8 ppm (w/w) water, respectively, has recently been the subject of debate in this journal. To shed some further light on this controversy, we report in this correspondence results for these oils obtained by two additional methods, one based on specially designed reagents for diaphragm-free Karl Fischer (KF) coulometry and the other based on the concept of stripping at elevated temperature/continuous KF coulometry. A positive interference effect was shown to take place for RM 8506 when the direct coulometric method was used. If the results are corrected for this, the values including six different procedures varied in the range 13.5-15.6 ppm (w/w). For RM 8507, all values were between 42.5 and 47.2 ppm (w/w), which means that the values recommended by NIST for both reference oils using volumetric titration are about twice as high as those obtained with the other techniques. A possible explanation for this discrepancy is presented.

  • 33. Chaintreau, Alain
    et al.
    Fieber, Wolfgang
    Sommer, Horst
    Gilbert, Alexis
    Yamada, Keita
    Yoshida, Naohiro
    Pagelot, Alain
    Moskau, Detlef
    Moreno, Aitor
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Reniero, Fabiano
    Holland, Margaret
    Guillou, Claude
    Silvestre, Virginie
    Akoka, Serge
    Remaud, Gerald S
    Site-specific C-13 content by quantitative isotopic C-13 nuclear magnetic resonance spectrometry: a pilot inter-laboratory study2013In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 788, p. 108-113Article in journal (Refereed)
    Abstract [en]

    Isotopic C-13 NMR spectrometry, which is able to measure intra-molecular C-13 composition, is of emerging demand because of the new information provided by the C-13 site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic C-13 NMR as a routine tool. This paper describes the first collaborative study of intra-molecular C-13 composition by NMR. The main goals of the ring test were to establish intra-and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic C-13 NMR was then assessed on vanillin from three different origins associated with specific delta C-13(i) profiles. The standard deviation was, on average, between 0.9 and 1.2 parts per thousand for intra-variability. The highest standard deviation for inter-variability was 2.1%. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of delta C-13(i) in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results.

    (C) 2013 Elsevier B.V. All rights reserved.

  • 34.
    Chelcea, Ioana C.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ahrens, Lutz
    Örn, Stefan
    Mucs, Daniel
    Andersson, Patrik L.
    Investigating the OECD database of per- and polyfluoroalkyl substances - chemical variation and applicability of current fate models2020In: Environmental Chemistry, ISSN 1448-2517, E-ISSN 1449-8979, Vol. 17, no 7, p. 498-508Article in journal (Refereed)
    Abstract [en]

    Environmental context A diverse range of materials contain organofluorine chemicals, some of which are hazardous and widely distributed in the environment. We investigated an inventory of over 4700 organofluorine compounds, characterised their chemical diversity and selected representatives for future testing to fill knowledge gaps about their environmental fate and effects. Fate and property models were examined and concluded to be valid for only a fraction of studied organofluorines. Many per- and polyfluoroalkyl substances (PFASs) have been identified in the environment, and some have been shown to be extremely persistent and even toxic, thus raising concerns about their effects on human health and the environment. Despite this, little is known about most PFASs. In this study, the comprehensive database of over 4700 PFAS entries recently compiled by the OECD was curated and the chemical variation was analysed in detail. The analysis revealed 3363 individual PFASs with a huge variation in chemical functionalities and a wide range of mixtures and polymers. A hierarchical clustering methodology was employed on the curated database, which resulted in 12 groups, where only half were populated by well-studied compounds thus indicating the large knowledge gaps. We selected both a theoretical and a procurable training set that covered a substantial part of the chemical domain based on these clusters. Several computational models to predict physicochemical and environmental fate related properties were assessed, which indicated their lack of applicability for PFASs and the urgent need for experimental data for training and validating these models. Our findings indicate reasonable predictions of the octanol-water partition coefficient for a small chemical domain of PFASs but large data gaps and uncertainties for water solubility, bioconcentration factor, and acid dissociation factor predictions. Improved computational tools are necessary for assessing risks of PFASs and for including suggested training set compounds in future testing of both physicochemical and effect-related data. This should provide a solid basis for better chemical understanding and future model development purposes.

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  • 35.
    Chen, Yang-Er
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. College of Life Sciences, Sichuan Agricultural University, Ya'an, China.
    Yuan, Shu
    Schröder, Wolfgang P.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparison of methods for extracting thylakoid membranes of Arabidopsis plants2016In: Physiologia Plantarum, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 156, no 1, p. 3-12Article in journal (Refereed)
    Abstract [en]

    Robust and reproducible methods for extracting thylakoid membranes are required for the analysis of photosynthetic processes in higher plants such as Arabidopsis. Here, we compare three methods for thylakoid extraction using two different buffers. Method I involves homogenizing the plant material witha metal/glass blender; method II involves manually grinding the plant materialin ice-cold grinding buffer with a mortar and method III entails snap-freezing followed by manual grinding with a mortar, after which the frozen powder is thawed in isolation buffer. Thylakoid membrane samples extracted using each method were analyzed with respect to protein and chlorophyll content, yields relative to starting material, oxygen-evolving activity, protein complex content and phosphorylation. We also examined how the use of fresh and frozen thylakoid material affected the extracts’ contents of protein complexes. The use of different extraction buffers did not significantly alter the protein contentof the extracts in any case. Method I yielded thylakoid membranes with the highest purity and oxygen-evolving activity. Method III used low amounts of starting material and was capable of capturing rapid phosphorylation changes in the sample at the cost of higher levels of contamination. Method II yielded thylakoid membrane extracts with properties intermediate between those obtained with the other two methods. Finally, frozen and freshly isolated thylakoid membranes performed identically in blue native-polyacrylamide gel electrophoresis experiments conducted in order to separate multimeric protein supracomplexes.

  • 36.
    Claeson, Anna-Sara
    et al.
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Gouveia-Figueira, Sandra C.
    Swedish Metabolomics Centre (SMC), Umeå, Sweden.
    Stenlund, Hans
    Swedish Metabolomics Centre (SMC), Umeå, Sweden.
    Johansson, Annika I.
    Swedish Metabolomics Centre (SMC), Umeå, Sweden.
    A standardized protocol for comparable analysis of GSH/GSSG by UHPLC-ESI-MSMS for human plasma2019In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1104, p. 67-72Article in journal (Refereed)
    Abstract [en]

    Variability in the levels of GSH and GSSG in plasma is suggested to derive from inadequate pre-processing methods. The aim of this study was to develop a protocol for comparable and reliable measurements of GSH/GSSG. Venous blood from 8 healthy individuals were collected and divided into 7 different pre-processing procedures. For three of the samples an extraction mixture was added after 0 (baseline), 4 and 8 min and for three of the samples the extraction mixture was added at different times during defrost. A worst case scenario where a sample was left in a cool box during 6 h was also included. The samples were analyzed with UHPLC-ESIMSMS. A large difference in the levels of GSH and GSSG were identified and it was clearly associated with the sample handling procedures. A sample left untreated for 4 min will have significantly reduced amount of GSH. Stability tests showed that the level of GSH was reduced after 3 months in -80 degrees C.

  • 37.
    Claeson, Anna-Sara
    et al.
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Lindberg, Richard H.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gouveia-Figueira, Sandra
    Nording, Malin L.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Feasibility and reliability of measures of bioactive lipids in human plasma and nasal mucosa2022In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1206, article id 123357Article in journal (Refereed)
    Abstract [en]

    Analysis of bioactive lipids is increasingly useful in clinical studies, and there is a need for non-invasive and easy-to-use sampling methods that meet the demands of reliability. Samples that can be taken by a non-professional and that can be taken repeatedly so as to provide more detailed information about the inflammatory process are often desired. In this study, the feasibility of non-invasive sampling of nasal mucosa and saliva for the analysis of bioactive lipid mediators (e.g. oxylipins and endocannabinoids) was evaluated in a pilot study (n = 10). In a second study, the reliability (relative and absolute) of sampling of these lipid mediators derived from nasal mucosa and from plasma was assessed by calculation of the intraclass correlation coefficient and Bland–Altman’s limit of agreement. Samples were taken at the same time of day on two occasions from a cohort of individuals with and without building-related intolerance (n = 37). Nasal mucosa proved to be a suitable matrix for the analysis of bioactive lipids and was therefore included in the study on reliability together with the plasma samples. Relative reliability varied among the identified oxylipins and endocannabinoids. Arachidonic acid derivatives showed generally better reliability. Absolute reliability measures also varied indicating that only a subset of the oxylipins and endocannabinoids were suitable as biomarkers in either nasal mucosa or plasma and should therefore be used with caution for that purpose.

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  • 38.
    Claeson, Anna-Sara
    et al.
    County Council of Västerbotten, Umeå, Sweden.
    Sandström, Maria
    County Council of Västerbotten, Umeå, Sweden.
    Sunesson, Anna-Lena
    County Council of Västerbotten, Umeå, Sweden.
    Volatile organic compounds (VOCs) emitted from materials collected from buildings affected by microorganisms2007In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 9, no 3, p. 240-245Article in journal (Refereed)
    Abstract [en]

    In this study mould damaged materials, including carpet, concrete, gypsum board, insulation, plastic, sand and wood, from 20 different buildings with moisture problems were collected. To study emissions from these materials both conventional methods for sampling, such as collection on Tenax TA, were used as well as complementary methods for sampling a wider spectrum of compounds, such as more volatile VOCs, amines and aldehydes. Analysis was carried out using gas chromatography and high-performance liquid chromatography. Mass spectrometry was used for identification of compounds. Alcohols and ketones were almost exclusively emitted from the materials after they had been wet for a week. Acids were also emitted in large quantities from wet gypsum board and plastic. No primary or secondary amines could be identified, but two tertiary amines, trimethylamine and triethylamine, were emitted from sand contaminated by Bacillus. The most common moulds found were Penicillium and Aspergillus. A multivariate method (partial least squares, PLS) was used to investigate the emission patterns from the materials. Materials with bacterial growth had a different VOC profile to those with only mould growth.

  • 39.
    Claeson, Anna-Sara
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Sunesson, Anna-Lena
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Identification using versatile sampling and analytical methods of volatile compounds from Streptomyces albidoflavus grown on four humid building materials and one synthetic medium2005In: Indoor Air, ISSN 0905-6947, E-ISSN 1600-0668, Vol. 15, no Suppl 9, p. 41-47Article in journal (Refereed)
  • 40.
    Claeson, Anna-Sara
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Östin, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Sunesson, Anna-Lena
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Development of a LC-MS/MS method for the analysis of volatile primary and secondary amines as NIT (naphthylisothiocyanate) derivatives2004In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 378, no 4, p. 932-939Article in journal (Refereed)
    Abstract [en]

    High-performance liquid chromatography with mass spectrometric detection was used for the structure elucidation of eighteen primary and secondary amines and ammonia derivatised with naphthylisothiocyanate (NIT). A fragmentation scheme was established using reference compounds and the scheme was applied to real air samples from a tyre repair shop and from the air above a bacterial culture. The sampling was performed using a solid sorbent, XAD-2, impregnated with NIT, and the derivatives were extracted with acetonitrile and analysed with LC-MS/MS. A three-step process was developed for screening and identifying of volatile amines. The first step, selected reaction monitoring; SRM was applied in order to screen the samples for NIT derivatives. In the second step, a precursor ion scan gave the [M+H]+ ion, and in the third step a product ion scan gave the fragments needed for identification. The detection limits varied between 0.12 and 0.25 ng μL−1 when screening for unknown derivatised amines. It was possible to separate and identify all the amines with the structural information obtained and the method proved to be general, sensitive and well suited for sampling and analysis of complex environmental samples.

  • 41.
    Courtois, Julien
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Monolithic separation media synthesized in capillaries and their applications for molecularly imprinted networks2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis describes the synthesis of chromatographic media using several different approaches, their characterizations and applications in liquid chromatography. The steps to achieve a separation column for a specific analyte are presented. The main focus of the study was the design of novel molecularly imprinted polymers.

    Attachment of monolithic polymeric substrates to the walls of fused silica capillaries was studied in Paper I. With a broad literature survey, a set of common methods were tested by four techniques and ranked by their ability to improve anchoring of polymers. The best procedure was thus used for all further studies.

    Synthesis of monoliths in capillary columns was studied in Paper II. With the goal of separating proteins without denaturation, various monoliths were polymerized in situ using a set of common monomers and cross-linkers mixed with poly(ethylene glycol) as porogen. The resulting network was expected to present “protein-friendly pores”. Chemometrics were used to find and describe a set of co-porogens added to the polymerization cocktails in order to get good porosity and flow-through properties.

    Assessment of the macroporous structure of a monolith was described in Paper III. An alternative method to mercury intrusion porosimetry was proposed. The capillaries were embedded in a stained resin and observed under transmission electron microscope. Images were then computed to determine the pore sizes.

    Synthesis of molecularly imprinted polymers grafted to a core mono-lith in a capillary was described in Paper IV. The resulting material, imprinted with local anaesthetics, was tested for its chromatographic performance. Similar imprinted polymers were characterized by microcalorimetry in Paper V. Finally, imprinted monoliths were also synthesized in a glass tube and further introduced in a NMR rotor to describe the interactions between stationary phase and template in Paper VI.

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  • 42.
    Dahlberg, Tobias
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Andersson, Magnus
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Optical design for laser tweezers Raman spectroscopy setups for increased sensitivity and flexible spatial detection2021In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 60, no 16, p. 4519-4523Article in journal (Refereed)
    Abstract [en]

    We demonstrate a method to double the collection efficiency in Laser Tweezers Raman Spectroscopy (LTRS) by collecting both the forward and back-scattered light in a single-shot multitrack measurement. Our method can collect signals at different sample volumes, granting both the pinpoint spatial selectivity of confocal Raman and the bulk sensitivity of non-confocal Raman simultaneously. Further, we display that our approach allows for reduced detector integration time and laser power. To show this, we measure the Raman spectra of both polystyrene beads and bacterial spores. For spores, we can trap them at 2.5 mW laser power and acquire a high signal-to-noise ratio Power spectrum of the CaDPA peaks using an integration time of 2 x 30 seconds. Thus, our method will enable the monitoring of biological samples sensitive to high intensities for longer times. Additionally, we demonstrate that by a simple modification, we can add polarization sensitivity and retrieve extra biochemical information. 

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  • 43.
    D'Amario, Luca
    et al.
    Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden; Department of Physics, Freie Universität Berlin, Berlin, Germany.
    Stella, Maria Bruna
    Department of Chemistry and Industrial Chemistry, University of Pisa, Pisa, Italy.
    Edvinsson, Tomas
    Department of Materials Science and Engineering, Uppsala University, Uppsala, Sweden.
    Persico, Maurizio
    Department of Chemistry and Industrial Chemistry, University of Pisa, Pisa, Italy.
    Messinger, Johannes
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Dau, Holger
    Department of Physics, Freie Universität Berlin, Berlin, Germany.
    Towards time resolved characterization of electrochemical reactions: electrochemically-induced Raman spectroscopy2022In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 13, no 36, p. 10734-10742Article in journal (Refereed)
    Abstract [en]

    Structural characterization of transient electrochemical species in the sub-millisecond time scale is the all-time wish of any electrochemist. Presently, common time resolution of structural spectro-electrochemical methods is about 0.1 seconds. Herein, a transient spectro-electrochemical Raman setup of easy implementation is described which allows sub-ms time resolution. The technique studies electrochemical processes by initiating the reaction with an electric potential (or current) pulse and analyses the product with a synchronized laser pulse of the modified Raman spectrometer. The approach was validated by studying a known redox driven isomerization of a Ru-based molecular switch grafted, as monolayer, on a SERS active Au microelectrode. Density-functional-theory calculations confirmed the spectral assignments to sub-ms transient species. This study paves the way to a new generation of time-resolved spectro-electrochemical techniques which will be of fundamental help in the development of next generation electrolizers, fuel cells and batteries.

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  • 44. De Brabandere, Heidi
    et al.
    Danielsson, Rolf
    Sjoberg, Per J. R.
    Ahlgren, Joakim
    Rydin, Emil
    Waldeback, Monica
    Sediment extraction and clean-up for organic phosphorus analysis by electrospray ionization tandem mass spectrometry2008In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 74, no 5, p. 1175-1183Article in journal (Refereed)
    Abstract [en]

    A method to prepare NaOH sediment extracts for organic P compound analysis with electrospray ionization tandem mass spectrometry (ESI-MS-MS) was developed on natural samples. Ion exchange, rotary evaporation and mass cut-off filtering proved to be suitable for sample preparation. Samples were analyzed with ESI-MS-MS, and reproducibility and repeatability of the method was calculated. In addition, P-31-nuclear magnetic resonance Spectroscopy (P-31 NMR)was used to measure recovery of different P compound groups such as orthophosphate (Ortho-P), orthophosphate monoesters (Monoester-P), orthophosphate diesters (Diester-P) and pyrophosphates (Pyro-P). The developed sample preparation method resulted in an easy-to-spray liquid for the ESI-MS-MS instrumentation. The overall P recovery was 65% and P-31 NMR showed that Diester-P, possibly in the form of DNA, was apparently lost through the filtering step most likely due to their size. Variances in the total intensities of the MS scans (relative standard deviation (R.S.D.) 35-54%) were for about 50% due to repeated MS runs. Covariances of the peaks in the MS spectra were calculated to be for about 30% due to the sample preparation procedure. Finally, with the ESI-MS-MS approach, 11 peaks in the mass spectra were found likely to represent phosphate containing compounds. (c) 2007 Elsevier B.V. All rights reserved.

  • 45. De Samber, Björn
    et al.
    De Rycke, Riet
    De Bruyne, Michiel
    Kienhuis, Michiel
    Sandblad, Linda
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Bohic, Sylvain
    Cloetens, Peter
    Urban, Constantin F.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Polerecky, Lubos
    Vincze, Laszlo
    Effect of sample preparation techniques upon single cell chemical imaging: A practical comparison between synchrotron radiation based X-ray fluorescence (SR-XRF) and Nanoscopic Secondary Ion Mass Spectrometry (nano-SIMS)2020In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 1106, p. 22-32Article in journal (Refereed)
    Abstract [en]

    Analytical capabilities of Nanoscopic Secondary Ion Mass Spectrometry (nano-SIMS) and Synchrotron Radiation based X-ray Fluorescence (SR nano-XRF) techniques were compared for nanochemical imaging of polymorphonuclear human neutrophils (PMNs). PMNs were high pressure frozen (HPF), cryosubstituted, embedded in Spurr's resin and cut in thin sections (500 nm and 2 mu m for both techniques resp.) Nano-SIMS enabled nanoscale mapping of isotopes of C, N, O, P and S, while SR based nano-XRF enabled trace level imaging of metals like Ca, Mn, Fe, Ni, Cu and Zn at a resolution of approx. 50 nm. The obtained elemental distributions were compared with those of whole, cryofrozen PMNs measured at the newly developed ID16A nano-imaging beamline at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. Similarities were observed for elements more tightly bound to the cell structure such as phosphorus and sulphur, while differences for mobile ions such as chlorine and potassium were more pronounced. Due to the observed elemental redistribution of mobile ions such as potassium and chlorine, elemental analysis of high pressure frozen (HPF), cryo-substituted and imbedded cells should be interpreted critically. Although decreasing analytical sensitivity occurs due to the presence of ice, analysis of cryofrozen cells - close to their native state - remains the golden standard. In general, we found nanoscale secondary ion mass spectrometry (nano-SIMS) and synchrotron radiation based nanoscopic X-ray fluorescence (SR nano-XRF) to be two supplementary alternatives for nanochemical imaging of single cells at the nanoscale. 

  • 46.
    Dejaegher, Bieke
    et al.
    Fund for Scientific Research, FWO, Vlaanderen, Belgium.
    Heyden, Yvan Vander
    Department of Analytical Chemistry and Pharmaceutical Technology, Research group on chemometrics and separation science, Vrije Universiteit Brussel, Belgium.
    Dumarey, Melanie
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Method development for drug impurity profiling: Part 12010In: LC GC Europe, ISSN 1471-6577, Vol. 23, no 4, p. 218-224Article in journal (Refereed)
    Abstract [en]

    In this Practical Data Handling column, method development for drug impurity profiling is discussed. This first part consists of the first two steps when developing a drug impurity profile: the selection of a suitable chromatographic column and the optimization of the mobile phase pH. Prior to the impurity profiling, the selection of a set of dissimilar chromatographic columns is made (i.e., columns with different selectivities) to be screened with the impurity mixture for selectivity differences.

  • 47.
    Dinh, Ngoc Phuoc
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Investigations of the retention mechanisms in hydrophilic interaction chromatography2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Hydrophilic interaction chromatography is well known as a powerful technique separation of polar and ionizable compound nowadays. However the retention mechanism of the technique is still under debate. Understanding retention mechanism would facilitate the method development using the technique and its future improvement. This was inspiring and became the goal of this thesis.

    This work involves the characterization of the water enriched layer regarding to water and buffer salt accumulation. Twelve HILIC stationary phase with a diverse surface chemistry regarding to function groups and modification type were studied. Effect of water and salt on regarding to the retention mechanism was investigated by correlating the adsorption data to the retention of selected solutes

    This also involved the characterization of interactions involve in the separation of 21 HILIC columns. Interactions was probe by retention ratio of pair solutes which are characteristic for each specific interaction. The data was evaluate using principle component analysis – a multivariable data analysis method. The model was comprehensive and its outcomes were confirmed by the studies on adsorptions of water and salts.

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    Investigations of the retention mechanisms in hydrophilic interaction chromatography
  • 48.
    Dinh, Ngoc Phuoc
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jonsson, Tobias
    Merck SeQuant AB, S-90719 Umeå, Sweden.
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Accumlations of ammonium acetate on polar materials under HILIC condition and its relation to retention of analytesManuscript (preprint) (Other academic)
    Abstract [en]

    Ammonium acetate is a buffer salt commonly added to mobile phase in HILIC to improve the reproducibility of the retention of analytes. Adding buffer salt would then result to the change in retention and selectivity. In this study, we have developed methods for determine ammonium acetate in form of its hydrolyzed products (ammonium ion and acetate ion) adsorption on twelve different HILIC stationary phases under various mobile phase condition. The effect of functional group and mobile phase compositions on salt adsorption was then discussed. We also tried to develop a method for characterization important retention mechanism of HILIC systems and interpreted them under the relationship with salt adsorption. Adsorption of salt was based on both portioning and electrostatic interaction. Ammonium was found to preferentially adsorb on HILIC stationary phases except Purospher Star NH2 phase. It is worth noting that adding salt to mobile phase can promote partitioning retention mechanism, possibly as a result of phase separation due to salt out effect.

  • 49.
    Dinh, Ngoc Phuoc
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Merck SeQuant AB, Umeå.
    Jonsson, Tobias
    Merck SeQuant AB, Umeå.
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Water uptake on polar stationary phases under conditions for hydrophilic interaction chromatography and its relation to solute retention2013In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1320, p. 33-47Article in journal (Other academic)
    Abstract [en]

    In hydrophilic interaction chromatography, water is known to accumulate on the stationary phase to form a water enriched layer, which is believed to play an important role in the retention mechanism. To gain a better understanding retention mechanism in HILIC, we have determined the water uptake on twelve different HILIC stationary phases. Non-modified and monomerically functionalized silica phases followed a pattern of monolayer formation followed by multiple layer adsorption, while the water uptake on polymerically functionalized silica stationary phase showed the characteristics of formation and swelling of hydrogels. This difference in the nature of water accumulation was found to be related to different water uptake patterns when methanol and tetrahydrofuran were added to 80:20 % (v/v) acetonitrile/water by replacing 5 % of the acetonitrile as tertiary solvents, and also when ammonium acetate was added as buffering electrolyte. The relationship between water uptake and retention mechanism was investigated by looking at the correlation between retention factors of neutral analytes and phase ratios of HILIC columns, calculated either as surface area (adsorption) or volume of the water layer enriched from the acetonitrile/water eluent (partitioning). Regardless of the adsorption or partitioning mechanism, the interaction of neutral analytes and stationary phase could be mainly the hydrogen bonding between analytes and the accumulated water in the water enriched layer.

  • 50.
    Dinh, Ngoc Phuoc
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nguyen, Anh Mai
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Quach, Minh Cam
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shchukarev, Andrei
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Functionalization of epoxy-based monoliths for ion exchange chromatography of proteins2009In: Journal of Separation Science, Vol. 32, no 15-16, p. 2556-2564Article in journal (Refereed)
    Abstract [en]

    Macroporous epoxy-based monoliths prepared by emulsion polymerization have been modified for use in ion exchange chromatography (IEC) of proteins. Strong anion exchange functionality was established by iodomethane quaternization of tertiary amine present on the monolith surface as a part of the polymer backbone. The modification pathway to cation exchange materials was via incorporation of glycidyl methacrylate (GMA) brushes which were coated using atom transfer radical polymerization (ATRP). Strong (SO3-) and weak (COO-) cation exchange groups were thereafter introduced onto the GMA-grafted monoliths by reactions with sodium hydrogen sulfite and iminodiacetic acid, respectively. Grafting was confirmed by XPS, gravimetric measurement, and chromatographic behavior of the modified materials toward model proteins. In incubation experiments the proteins were recovered quantitatively with no obvious signs of unfolding after contact with the stationary phase for >2 h. Chromatographic assessments on the functionalized columns as well as problems associated with flow-through modification by ATRP are discussed.

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