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  • 151. Sukhrobov, Parviz
    et al.
    Numonov, Sodik
    Mamat, Xamxikamar
    Li, Yongtao
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Hu, Guangzhi
    Umeå University, Faculty of Science and Technology, Department of Physics. Key Laboratory of Chemistry of Plant Resources in Arid Regions, State Key Laboratory Basis of Xinjiang Indigenous Medicinal Plants Resource Utilization, Xinjiang Technical Institute of Physics .
    A New Non-Enzymatic Amperometric Sensor Based on Nickel Decorated ZIF-8 Derived Carbon Nanoframe for the Glucose Determination in Blood Samples2018In: International Journal of Electrochemical Science, ISSN 1452-3981, E-ISSN 1452-3981, Vol. 13, no 7, p. 6550-6564Article in journal (Refereed)
    Abstract [en]

    The present study demonstrated a highly sensitive non-enzymatic glucose biosensor in real blood samples based on simple evaluated nickel deposited on N-doped porous carbon modified glassy carbon electrode (Ni/NPC/GCE) by applying electrochemical deposition method. The prepared material initially were characterized by cyclic voltammetry, the morphology structure of the as-prepared samples was observed by SEM, and composition, crystals structure of Ni/NPC were identified by SEM mapping and EDS tests. The Ni/NPC/GCE compared with NPC/GCE and NiNPs/GCE performed the best electrocatalytic behavior towards oxidation of glucose in 0.1 M KOH medium. By applied potential of +0.6 V Ni/NPC/GCE showed very high sensitivity of 3753.78 mu AmM(-1)cm(-2) in linear range of 1-7940 mu M with the correlation coefficient of R-2=0.995. The linear ranges get views above the concentration up to 7940 mu M with the detection limit of 0.3 mu M (S/N= 3). Amperometric time responses of prepared electrode towards different glucose concentrations are 0.8-1.3s. Finally, several positive characteristics such as very high sensitivity, weak working potential, nice anti-interference properties, long stability, good selectivity, and comparison with some other non-enzymatic sensors Ni/NPC/GCE executed high sensitivity, low detection limit and wide linear range to glucose sensing, thus the selected electrode is supplying for future glucose level determination design.

  • 152.
    Sunesson, Anna-Lena
    Umeå University, Faculty of Science and Technology, Department of Chemistry. National Institute for Working Life Analytical Chemistry Division Umeå, Sweden.
    Volatile metabolites from microorganisms in indoor environments: sampling, analysis and identification1995Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Microorganisms are able to produce a wide variety of volatile organic compounds. This thesis deals with sampling, analysis and identification of such compounds, produced by microorganisms commonly found in buildings.

    The volatiles were sampled on adsorbents and analysed by thermal desorption cold trap-injection gas chromatography, with flame ionization and mass-spectrometric detection. The injection was optimized, with respect to the recovery of adsorbed components and the efficiency of the chromatographic separation, using multivariate methods. Eight adsorbents were evaluated with the object of finding the most suitable for sampling microbial volatiles. Among the adsorbents tested, Tenax TA proved to have the best properties for the purpose. Some carbon-containing adsorbents, e.g., Tenax GR and Carbopack B, showed a catalytic effect on thermal decomposition of some compounds, mainly terpene derivatives.

    Five fungal species, Aspergillus versicolor, Pénicillium commune, Cladosporium cladosporioides, Paecilomyces variotii and Phialophora fastigiata, and anactinomycete, Streptomyces albidoflavus, were cultivated on various artificial media and/or building materials. Cultivation was performed in culture flasks, provided with air inlet and outlet tubes. Humidified air was constantly led through the flasks, and samples were taken by attaching adsorbent tubes to the outlet tubes of the flasks. The cultivation medium proved to be of vital importance for metabolite production, quantitatively as well as qualitatively. For Streptomyces albidoflavus the effect of medium, cultivation temperature, and oxygen and carbon dioxide levels in the supplied air on the production of volatiles, was studied using multivariate techniques. The medium and the temperature exerted the largest influence, but the oxygen and carbon dioxide levels also affected the amounts of some metabolites produced.

    The produced volatile metabolites were identified by mass spectrometry and reference compounds. Alcohols, ketones, sulphur compounds and terpenes were most frequently found, but hydrocarbons, ethers and esters were also produced by some species. Among the most commonly produced metabolites, which are also suggested as potential indicator substances for excessive growth of microorganisms in buildings, were 3-methyl-1-butanol, 2-methyl-1-butanol, 3-methyl-2-butanone, 3-methyl-2-pentanone, dimethyl disulphide, -methylfuran, 2,5-dimethylfuran and geosmin.

  • 153.
    Surowiec, Izabella
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Sartorius Stedim Data Analytics, Tvistevägen 48, 907 36 Umeå, Sweden.
    Skotare, Tomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjögren, Rickard
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Sartorius Stedim Data Analytics, Tvistevägen 48, 907 36 Umeå, Sweden.
    Gouveia-Figueira, Sandra C.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Orikiiriza, Judy Tatwan
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Normark, Johan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Sartorius Stedim Data Analytics, Tvistevägen 48, 907 36 Umeå, Sweden.
    Joint and unique multiblock analysis of biological data: multiomics malaria study2019In: Faraday discussions (Online), ISSN 1359-6640, E-ISSN 1364-5498, Vol. 218, p. 268-283Article in journal (Refereed)
    Abstract [en]

    Modern profiling technologies enable obtaining large amounts of data which can be later used for comprehensive understanding of the studied system. Proper evaluation of such data is challenging, and cannot be faced by bare analysis of separate datasets. Integrated approaches are necessary, because only data integration allows finding correlation trends common for all studied data sets and revealing hidden structures not known a priori. This improves understanding and interpretation of the complex systems. Joint and Unique MultiBlock Analysis (JUMBA) is an analysis method based on the OnPLS-algorithm that decomposes a set of matrices into joint parts containing variation shared with other connected matrices and variation that is unique for each single matrix. Mapping unique variation is important from a data integration perspective, since it certainly cannot be expected that all variation co-varies. In this work we used JUMBA for integrated analysis of lipidomic, metabolomic and oxylipin datasets obtained from profiling of plasma samples from children infected with P. falciparum malaria. P. falciparum is one of the primary contributors to childhood mortality and obstetric complications in the developing world, what makes development of the new diagnostic and prognostic tools, as well as better understanding of the disease, of utmost importance. In presented work JUMBA made it possible to detect already known trends related to disease progression, but also to discover new structures in the data connected to food intake and personal differences in metabolism. By separating the variation in each data set into joint and unique, JUMBA reduced complexity of the analysis, facilitated detection of samples and variables corresponding to specific structures across multiple datasets and by doing this enabled fast interpretation of the studied system. All this makes JUMBA a perfect choice for multiblock analysis of systems biology data.

  • 154.
    Surowiec, Izabella
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Vikström, Ludvig
    Hector, Gustaf
    Johansson, Erik
    Vikström, Conny
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Generalized Subset Designs in Analytical Chemistry2017In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 89, no 12, p. 6491-6497Article in journal (Refereed)
    Abstract [en]

    Design of experiments (DOE) is an established methodology in research, development, manufacturing, and production for screening, optimization, and robustness testing. Two-level fractional factorial designs remain the preferred approach due to high information content while keeping the number of experiments low. These types of designs, however, have never been extended to a generalized multilevel reduced design type that would be capable to include both qualitative and quantitative factors. In this Article we describe a novel generalized fractional factorial design. In addition, it also provides complementary and balanced subdesigns analogous to a fold-over in two-level reduced factorial designs. We demonstrate how this design type can be applied with good results in three different applications in analytical chemistry including (a) multivariate calibration using microwave resonance spectroscopy for the determination of water in tablets, (b) stability study in drug product development, and (c) representative sample selection in clinical studies. This demonstrates the potential of generalized fractional factorial designs to be applied in many other areas of analytical chemistry where representative, balanced, and complementary subsets are required, especially when a combination of quantitative and qualitative factors at multiple levels exists.

  • 155. Taubald, H.
    et al.
    Tonderski, K.
    Andersson, L.
    Ronnberg, R.
    Ahlgren, J.
    Oxygen isotopes in phosphate as a tracer for sources and pathways of catchment P in stream water2010In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 74, no 12, p. A1030-A1030Article in journal (Other academic)
  • 156.
    Tesfalidet, Solomon
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Determination of Organometallic Compounds Using Species Specific Isotope Dilution and GC-ICP-MS2012In: Advanced Gas Chromatography: Progress in Agricultural, Biomedical and Industrial Applications / [ed] Mustafa Ali Mohd, INTECH, 2012, p. 389-404Chapter in book (Refereed)
  • 157.
    Torell, Frida
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Skotare, Tomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Multi-Tissue Metabolomics Integration Utilising Hierarchical Modelling and Data Integration MethodsManuscript (preprint) (Other academic)
  • 158.
    Trygg, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gabrielsson, Jon
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lundstedt, T.
    Data Preprocessing: Background Estimation, Denoising, and Preprocessing ...2009In: Comprehensive Chemometrics: Chemical and Biochemical Data Analysis, VOL 1-4 / [ed] Steven Brown, Romà Tauler, Beata Walczak, AMSTERDAM: Elsevier, 2009, p. A1-A8Chapter in book (Other academic)
  • 159.
    Trygg, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johansson, Erik
    Umetrics AB.
    Eliasson, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Optimization of Data Processing Parameters2012Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Abstract: Described are computer-based methods and apparatuses, including computer program products, for optimizing data processing parameters. A data set is received that represents a plurality of samples. The data set is processed using a data processing algorithm that includes one or more processing stages, each stage using a respective first set of data processing parameters to generate processed data. A design of experiment model is generated for the data processing algorithm based on the processed data and a set of response values. For each stage of the data processing algorithm, a second set of data processing parameters is calculated based on at least the design of experiment model.

  • 160.
    Trygg, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wold, Svante
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umetrics AB.
    Orthogonal signal projection2003Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Abstract: The invention regards a method and an arrangement for filtering or pre-processing most any type of multivariate data exemplified by NIR or NMR spectra measured on samples in order to remove systematic noise such as base line variation and multiplicative scatter effects. This is accomplished by differentiating the spectra to first or second derivatives, by Multiplicative Signal Correction (MSC), or by similar filtering methods. The pre-processing may, however, also remove information from the spectra, as well as other multiple measurement arrays, regarding (Y) (the response variables). Provided is a variant of PLS that can be used to achieve a signal correction that is as close to orthogonal as possible to a given (y) vector or (Y) matrix. Hence, ensuring that the signal correction removes as little information as possible regarding (Y). A filter according to the present invention is named Orthogonal Partial Least Squares (OPLS).

  • 161.
    Veenaas, Cathrin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Developing tools for non-target analysis and digital archiving of organic urban water pollutants2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes efforts to develop robust methods for the creation and use of digital archives of environmental samples, and proposes guidelines based on the results. Digital archives are repositories that store environmental samples digitally. Traditionally, samples are stored physically in environmental specimen banks over long time periods. However, this has several drawbacks, for example degradation effects and limited accessibility. During the course of my PhD project I developed methods that allow the comprehensive analysis of sewage sludge samples. Sewage sludge is a complex matrix that contains many commercial chemicals. In addition, sewage treatment plants form a link between the human society that generates the sewage and the environment, making sewage sludge a very interesting matrix to analyze. The developed methods enable analysis and subsequent identification of compounds of all sizes and with diverse chemical characteristics. I further explain how unknown compounds can be identified (non-target screening) using mass spectral analysis and several other approaches (e.g. retention indices).

    The thesis is divided into three parts. In the first part, Data Generation, I describe the development of sample preparation methods for analyzing sewage sludge with gas chromatography (GC) and liquid chromatography (LC) coupled to high resolution mass spectrometry (HRMS). For the GC approach, two methods involving use of different extraction techniques, solvents, and matrix reduction techniques are presented while for the LC approach different extraction techniques are compared. The methods have been developed to enable the generation of data suitable for digital archiving. In the second part of the thesis, Data Evaluation, I present ways to find and identify compounds of interest. Firstly, time trend analyses provide a way to prioritize pollutants, for example by focusing on pollutants that are increasing with time. Thousands of compounds with significant time trends were detected and several hundred of them were tentatively identified. Compounds with strong increasing trends included, for example, UV-filters from sunscreens. Secondly, a new retention index system for comprehensive two‑dimensional chromatography (GC×GC) is introduced to characterize compounds in terms of their retention times in the second dimension. The new retention index system is based on co-injection of polyethylene glycols and was validated for various compounds of diverse classes. Thirdly, I tested different ways to predict GC×GC retention times or indices. Those methods include a multivariate prediction (PLS) approach using molecular descriptors, which proved to be the best approach, and use of commercially available software. The last part of my thesis, Data Archiving, discusses requirements to create digital archives and how they can be used. Here I present the current state and options for archiving data files, and give recommendations for each step, from sample collection, through instrumental analysis to storage of the final data.

  • 162.
    Veenaas, Cathrin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A retention index system for comprehensive two-dimensional gas chromatography using polyethylene glycols2018In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1536, p. 67-74Article in journal (Refereed)
    Abstract [en]

    The characterization and identification of compounds in complex real-world samples is quite difficult and new concepts and workflows are highly desirable. Retention indices (RIs) are widely used in gas chromatography (GC) to support the identification of unknown compounds. Several attempts have been made to introduce a similar concept for the second dimension in comprehensive two-dimensional (2D) GC (GC × GC) but, an easily applicable and robust system remains elusive. In the present study, a new RI system for GC × GC was developed. Polyethylene glycols (PEGs) were used in combination with a simple linear regression, with n-alkanes as reference points for virtually unretained compounds and PEG homologs as reference compounds for second-dimension RIs (PEG-2I). The n-alkanes were assigned a PEG-2I of zero and the distance between consecutive PEG homologs from PEG-2 (diethylene glycol) and higher were assigned a PEG-2I value of 10. We used ethylene glycol and PEG-2 through PEG-10 as reference compounds, thereby covering a PEG-2I range from 20.0 for ethylene glycol, over 50.0 for diethylene glycol (PEG-2) to 130.0 for decaethylene glycol (PEG-10); additional PEGs can be added to cover a wider polarity range. The PEG-2I system was initially evaluated using a 30 m × 0.25 mm non-polar (5% phenyl, 0.25 μm film thickness) first-dimension column and a 1.6 m × 0.18 mm polar (50% phenyl, 0.18 μm film thickness) second-dimension column. This system was validated for use with non-polar first-dimension columns and a semi-polar (50% phenyl) second-dimension column, and exhibited robustness to changes in the carrier gas flow velocity, oven temperature ramping rate, and secondary oven temperature offset. An average relative standard deviation of 2.7%, equal to a 95% confidence interval of 1.27 PEG-2I units, was obtained for the PEG-2I values of 72 environmental pollutants. Additionally, the system was found to be applicable over a wide range of boiling points (in the current case, from n-heptane to n-dotriacontane (C7-C32)) and can be used with various column dimensions. Changing the second-dimension column to either a narrower 0.1 mm column or a wider 0.25 mm column, yielded similar 95%-percentiles to that of the 0.18 mm column, differing by only 3.20 and 2.80 PEG-2I units, respectively. Moreover, methods for improving the system were suggested.

  • 163.
    Veenaas, Cathrin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Methodology for non-target screening of sewage sludge using comprehensive two-dimensional gas chromatography coupled to high-resolution mass spectrometry2017In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 409, no 20, p. 4867-4883Article in journal (Refereed)
    Abstract [en]

    To investigate the wide range of pollutants occurring in sewage sludge, an analytical method for comprehensive nontarget screening is needed. To the best of our knowledge, no procedures currently exist for the full screening of organic contaminants in sewage sludge, which is the ultimate goal of this project. We developed non-discriminating sample preparation methods for gas chromatography-mass spectrometry (GC-MS) analysis. Pressurized liquid extraction (PLE) was used for extraction, with in-line (silica gel selective PLE, SPLE) or off-line clean-up (gel permeation chromatography, GPC). This combination allowed the analysis of non-polar compounds of all sizes and small semi-polar and non-polar compounds. The results show that the combination of SPLE and PLE with GPC is suitable for analysis of established as well as new contaminants. Both methods were validated for 99 compounds with different properties. For all GC suitable analytes, either one of the methods produced acceptable recoveries (64 to 136%). As a test, the two methods were used for non-target screening of Swedish sewage sludge. A tiered approach was used to tentatively identify the sludge contaminants. In total, 1865 and 1593 compounds were found of which 321 and 192 compounds were tentatively identified for the PLE and SPLE method, respectively. For a comprehensive coverage of contaminants, the two methods should be used together, with the PLE method covering a wider polarity range and the SPLE method a wider size range. In addition, polar substances will require liquid chromatography-mass spectrometry analysis, the method for which will be developed soon.

  • 164.
    Veenaas, Cathrin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Retention-time prediction in comprehensive two-dimensional gas chromatography to aid identification of unknown contaminants2018In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 410, no 30, p. 7931-7941Article in journal (Refereed)
    Abstract [en]

    Comprehensive two-dimensional (2D) gas chromatography (GC×GC) coupled to mass spectrometry (MS, GC×GC-MS), which enhances selectivity compared to GC-MS analysis, can be used for non-directed analysis (non-target screening) of environmental samples. Additional tools that aid in identifying unknown compounds are needed to handle the large amount of data generated. These tools include retention indices for characterizing relative retention of compounds and prediction of such. In this study, two quantitative structure–retention relationship (QSRR) approaches for prediction of retention times (1tR and 2tR) and indices (linear retention indices (LRIs) and a new polyethylene glycol–based retention index (PEG-2I)) in GC × GC were explored, and their predictive power compared. In the first method, molecular descriptors combined with partial least squares (PLS) analysis were used to predict times and indices. In the second method, the commercial software package ChromGenius (ACD/Labs), based on a “federation of local models,” was employed. Overall, the PLS approach exhibited better accuracy than the ChromGenius approach. Although average errors for the LRI prediction via ChromGenius were slightly lower, PLS was superior in all other cases. The average deviations between the predicted and the experimental value were 5% and 3% for the 1tR and LRI, and 5% and 12% for the 2tR and PEG-2I, respectively. These results are comparable to or better than those reported in previous studies. Finally, the developed model was successfully applied to an independent dataset and led to the discovery of 12 wrongly assigned compounds. The results of the present work represent the first-ever prediction of the PEG-2I.

  • 165.
    Veenaas, Cathrin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Linusson Jonsson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Retention time prediction in comprehensive two-dimensional gas chromatography to aid identification of unknown contaminantsManuscript (preprint) (Other academic)
  • 166. Vidal, Lorena
    et al.
    Robin, Orlane
    Parshintsev, Jevgeni Parshintsev
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Riekkola, Marja-Liisa Riekkola
    Quaternary ammonium-functionalized silica sorbents for the solid-phase extraction of aromatic amines under normal phase conditions2013In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1285, p. 7-14Article in journal (Refereed)
    Abstract [en]

    Quaternary ammonium-functionalized silica materials were synthesized and applied for solid-phase extraction (SPE) of aromatic amines, which are classified as priority pollutants by US Environmental Protection Agency. Hexamethylenetetramine used for silica surface modification for the first time was employed as SPE sorbent under normal phase conditions. Hexaminium-functionalized silica demonstrated excellent extraction efficiencies for o-toluidine, 4-ethylaniline and quinoline (recoveries 101-107%), while for N,N-dimethylaniline and N-isopropylaniline recoveries were from low to moderate (14-46%). In addition, the suitability of 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica as SPE sorbent was tested under normal phase conditions. The recoveries achieved for the five aromatic amines ranged from 89 to 99%. The stability of the sorbent was evaluated during and after 150 extractions. Coefficients of variation between 4.5 and 10.2% proved a high stability of the synthesized sorbent.

    Elution was carried out using acetonitrile in the case of hexaminium-functionalized silica and water for 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica sorbent.After the extraction the analytes were separated and detected by liquid chromatography ultraviolet detection (LC-UV). The retention mechanism of the materials was primarily based on polar hydrogen bonding and π-π interactions. Comparison made with activated silica provedthe quaternary ammonium-functionalized materials to offer different selectivity and better extraction efficiencies for aromatic amines. Finally, 1-alkyl-3-(propyl-3-sulfonate) imidazolium-functionalized silica sorbent was successfully tested for the extraction of wastewater and soil samples.

  • 167.
    Virel, Ana
    et al.
    CIC biomaGUNE, Parque Tecnologico de San Sebastian, Paseo Miramon 182, San Sebastian, Spain .
    Saa, Laura
    Köster, Stephan David
    Pavlov, Valeri
    Ultrasensitive optical detection of hydrogen peroxide by triggered activation of horseradish peroxidase2010In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 135, no 9, p. 2291-2295Article in journal (Refereed)
    Abstract [en]

    Hydrogen peroxide is a very reactive byproduct of many metabolic pathways. We describe an ultra-sensitive colorimetric method to detect hydrogen peroxide based on the reconstitution of apo-horseradish peroxidase with the hemin derivative, hemin di(N,N'-acetyl-hydrazide). Oxidation of the latter by hydrogen peroxide yields hemin, which is able to reconstitute apo-horseradish peroxidase, forming an active peroxidase. We have also applied this analyte-triggered reconstitution of horseradish peroxidase to detect the activity of the enzyme glucose oxidase.

  • 168. Wang, Shijun
    et al.
    Milam, Jenifer
    Ohlin, C. Andre
    Rambaran, Varma H.
    Clark, Eva
    Ward, Woodrow
    Seymour, Luke
    Casey, William H.
    Holder, Alvin A.
    Miao, Wujian
    Electrochemical and Electrogenerated Chemiluminescent Studies of a Trinuclear Complex, [((phen)2Ru(dpp))2RhCl2]5+, and Its Interactions with Calf Thymus DNA2009In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 81, no 10, p. 4068-4075Article in journal (Refereed)
    Abstract [en]

    The electrochemical behavior of a trinuclear ruthenium(II)-containing complex, [((phen)2Ru(dpp))2RhCl2]5+ (where phen = 1,10-phenanthroline, dpp = 2,3-bis(2-pyridyl)pyrazine), was studied in acetonitrile (MeCN) and aqueous solutions. In MeCN containing 0.10 M tetra-n-butylammonium perchlorate (TBAP), the complex displayed a reversible, overlapping RuII/III redox process with E1/2 = +1.21 V vs Ag/Ag+ (10 mM), an irreversible reduction of RhIII/I at −0.73 V vs Ag/Ag+, and two quasi-reversible dpp/dpp− couples with E1/2 = −1.11 and −1.36 V vs Ag/Ag+ at a Pt electrode with a scan rate of 50 mV s−1. In 0.20 M Tris buffer solution (pH 7.4), an irreversible, overlapping RuII/III oxidation at +1.48 V vs Ag/AgCl (3 M KCl), and an irreversible reduction of RhIII/II at −0.78 V vs Ag/AgCl were observed at a glassy carbon electrode with a scan rate of 50 mV/s. Investigations on the electrogenerated chemiluminescence (ECL) of the complex revealed that 2-(dibutylamino) ethanol (DBAE) was superior to tri-n-propylamine (TPrA) as an ECL coreactant within their entire concentration range of 10−100 mM in MeCN, and in aqueous media, as low as 1.0 nM of the complex can be detected using TPrA coreactant ECL. A maximum ECL emission of 640 nm, which is about 55 nm blue shift to its fluorescence, was observed in MeCN with DBAE as a coreactant. Interactions of the complex with calf thymus DNA (ctDNA) were conducted with a flow-cell based quartz-crystal microbalance, and a binding constant of 2.5 × 105 M−1 was calculated on the basis of the Langmuir isotherm equation.

  • 169. Werner, K
    et al.
    Borén, E
    Broström, M
    Pommer, L
    Comprehensive study of the pyrolytic degradation of different hemicelluloses2013Conference paper (Refereed)
  • 170.
    Wiberg, Karin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Letcher, Robert
    Sandau, Courtney
    Duffe, Jason
    Norstrom, Ross
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bidleman, Terry
    Enantioselective gas chromatography/mass spectrometry of methylsulfonyl PCBs with application to arctic marine mammals1998In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 70, no 18, p. 3845-3852Article in journal (Refereed)
    Abstract [en]

    Four different commercially available cyclodextrin (CD) capillary gas chromatography (GC) columns were tested for the enantioselective separation of nine environmentally persistent atropisomeric 3- and 4-methylsulfonyl PCBs (MeSO2-CBs). The selected columns contained cyclodextrins with various cavity diameters (β- or γ-CD), which were methylated and/or tert-butyldimethylsilylated (TBDMS) in the 2,3,6-O-positions. The β-CD column with TBDMS substituents in all of the 2,3,6-O-positions was by far the most selective column for the MeSO2-CBs tested. Enantiomers of congeners with 3-MeSO2 substitution were more easily separated than those with 4-MeSO2 substitution. The separation also seemed to be enhanced for congeners with the chlorine atoms on the non-MeSO2-containing ring and clustered on one side of the same ring. The 2,3-di-O-methyl-6-O-TBDMS-β-CD was found to give somewhat better selectivity than the corresponding γ-CD, in comparison between the two columns, which were identical in all other respects. Enantioselective analysis of arctic ringed seal (Phoca hispida) and polar bear (Ursus maritimus) adipose tissue revealed a strong dominance of certain enantiomers. For example, the enantiomer ratio (ER) of 3-MeSO2-CB149 was 0.32 and <0.1 in ringed seal blubber and polar bear fat, respectively. These low ER values are indicative of highly enantioselective formation, enantioselective metabolism, enantioselective transport across cell membranes, or a combination of the three in both species. Comparable results for the enantiomeric analysis of MeSO2-CBs in biotic tissue extracts were obtained using two highly selective mass spectrometric techniques, ion trap mass spectrometry/mass spectrometry and electron capture negative ion low-resolution mass spectrometry.

  • 171.
    Wikberg, Erika
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Zwitterionic Sulfobetaine Polymers as Stationary Phases for Liquid Chromatography2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Liquid chromatography is an important separation technique for a vast number of analytes. This thesis mainly focuses on the development of stationary phases for liquid chromatography based on zwitterionic sulfobetaine polymers.

    In the thesis, various ways to prepare zwitterionic polymers in an aqueous environment using reversible addition fragmentation chain transfer (RAFT) polymerization are described. Both telomers, i.e. short soluble polymer chains containing a functional terminal group, as well as graft polymers on various supports have been synthesized. The RAFT polymerization technique provides an increased degree of control of the final polymers, which may aid in the preparation of more specifically tailored separation materials.

    Sulfobetaine polymers carry both a positive and a negative charge within a single entity, which results in interesting solution properties as well as highly biocompatible features. These unique features make them especially suited for separation of highly polar and/or charged compounds. An example of the successful separation of short peptides using a stationary phase synthesized with the RAFT technique is given.

    The unusual properties of sulfobetaine-type polymers are believed to be associated with the structure of water close to the polymer. A study of water structure in some silica based stationary phase grafted with zwitterionic sulfobetaine polymers was conducted. The impact of water structure on retention characteristics was investigated.

  • 172.
    Wikberg, Erika
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Verhage, Jeroen J
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Viklund, Camilla
    Merck SeQuant AB, Umeå, Sweden.
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Grafting of silica with sulfobetaine polymers via aqueous reversible addition fragmentation chain transfer polymerization and its use as a stationary phase in HILIC2009In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 32, no 12, p. 2008-2016Article in journal (Refereed)
    Abstract [en]

    Porous silica particles of 3 mum diameter and 100 A nominal pore size were first activated for vinylic polymerization by functionalization with 3-methacryloyloxypropyl trimethoxysilane (MAPTMS) and thereafter dressed with zwitterionic grafts of the sulfoalkylbetaine type in the "grafting through" fashion by polymerizing 3-(2-(N-methacryloyloxyethyl)-N,N-dimethylammonio)propane sulfonate (SPE), using either free radical polymerization or controlled reversible addition fragmentation chain transfer polymerization (RAFT). Particles polymerized using RAFT had a lower overall coating which seemed to be more evenly distributed in the pore volume. Both approaches resulted in columns with similar separation properties in HILIC mode.

  • 173.
    Wold, Svante
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Chemometrics and Bruce: Some Fond Memories2015In: 40 Years of Chemometrics – From Bruce Kowalski to the Future, 2015, Vol. 1199, p. 1-13Conference paper (Refereed)
    Abstract [en]

    This chapter describes the transformation of a young physical organic chemist (SW, 1964), from a believer in first principles models to a middle-aged chemometrician (SW, 1974) promoting empirical and semiempirical "data driven, soft, analogy" models for the design of experiments and the analysis of the resulting data. This transformation was marked by a number of influential events, each tipping the balance towards the data driven, soft, analogy models until the point of no return in 1974. On June 10, 1974, Bruce and I together with our research groups joined forces formed the Chemometrics Society (later renamed to the International Chemometrics Society), and we took off into multidimensional space. This review of my personal scientific history, inspired and encouraged by Bruce, is illustrated by examples of method development driven by necessity to solve specific problems and leading to data driven soft models, which, at least in my own eyes, were superior to the classical first principles approaches to the same problems. Bruce and I met at numerous conferences between 1975 and 1990, but after that, Bruce and I gradually slid out of the academic world, and now Bruce has taken his final step.

  • 174.
    Wold, Svante
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kettaneh-Wold, N.
    MacGregor, J. F.
    Dunn, K. G.
    Batch Process Modeling and MSPC2009In: Comprehensive Chemometrics: Chemical and Biochemical Data Analysis, VOLS 1-4 / [ed] Steven Brown, Romà Tauler, Beata Walczak, AMSTERDAM: Elsevier, 2009, p. A163-A197Chapter in book (Other academic)
  • 175.
    Wu, Jufang
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Modeling adsorption of organic compounds on activated carbon: a multivariate approach2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Activated carbon is an adsorbent that is commonly used for removing organic contaminants from air due to its abundant pores and large internal surface area. This thesis is concerned with the static adsorption capacity and adsorption kinetics for single and binary organic compounds on different types of activated carbon. These are important parameters for the design of filters and for the estimation of filter service life. Existing predictive models for adsorption capacity and kinetics are based on fundamental “hard” knowledge of adsorption mechanisms. These models have several drawbacks, especially in complex situations, and extensive experimental data are often needed as inputs. In this work we present a systematic approach that can contribute to the further development of predictive models, especially for complex situations. The approach is based on Multivariate Data Analysis (MVDA), which is ideally suited for the development of soft models without incorporating any assumptions about the mathematical form or fundamental physical principles involved.

    Adsorption capacity and adsorption kinetics depend on the properties of the carbon and the adsorbate as well as experimental conditions. Therefore, to make general statements regarding adsorption capacity and kinetics it is important for the resulting models to be representative of the conditions they will simulate. Accordingly, the first step in the investigations underlying this thesis was to select a minimum number of representative and chemically diverse organic compounds. The next steps were to study the dependence of the derived affinity coefficient, β, in the Dubinin-Radushkevich equation on properties of organic compounds and to establish a new, improved model. This new model demonstrates the importance of adding descriptors for the specific interaction with the carbon surface to the size and shape descriptors. The adsorption capacities of the same eight organic compounds at low relative pressures were correlated with compound properties. It was found that different compound properties are important in the various stages of adsorption, reflecting the fact that different mechanisms are involved. Ideal adsorbed solution theory (IAST) in combination with the Freundlich equation was developed to predict the adsorption capacities of binary organic compound mixtures. A new model was proposed for predicting the rate coefficient of the Wheeler-Jonas equation which is valid for breakthrough ratios up to 20%. Finally, it was shown that the Wheeler-Jonas equation can be adapted to describe the breakthrough curves of binary mixtures. New models were proposed for predicting its parameters, the adsorption rate coefficients, and the adsorption capacities for both components of the binary mixture. Thus, multivariate data analysis can not only be used to assist in the understanding of adsorption mechanisms, but also contribute to the development of predictive models of adsorption capacity and breakthrough time for single and binary organic compounds.

  • 176. Yekta, Sepehr Shakeri
    et al.
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Stehr, Jan Eric
    Dario, Mårten
    Hertkorn, Norbert
    Björn, Annika
    Pretreatment of anaerobic digester samples by hydrochloric acid for solution-state H-1 and C-13 NMR spectroscopic characterization of organic matter2018In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 199, p. 201-209Article in journal (Refereed)
    Abstract [en]

    Pretreatment of anaerobic digester samples by hydrochloric acid (HCl) resulted in removal of Fe-based mineral and coordination compounds, attenuating their interferences with solution-state nuclear magnetic resonance (NMR) spectroscopic characterization of the solid phase organic matter. Substrate (influent) and digestate (effluent) samples from two full-scale anaerobic digesters, designated CD (co-digester) and SSD (sewage sludge digester), were investigated. Pretreatment of CD samples with 0.2-2.0 mol l(-1) HCl and pretreatment of SSD samples with 1.0-3.0 mol l(-1) HCl removed 96-100% and 76-80% of total Fe, respectively. Pretreatment declined overall paramagnetic characteristics of digestate samples, manifested by 50% (CD) and 70% (SSD) decrease in electron paramagnetic resonance signal intensities. As a result, meaningful solution-state H-1,C-13 heteronuclear single quantum coherence and H-1 NMR spectra of DMSO-d(6) soluble organic matter could be acquired. Sample pretreatment with the lowest concentration of HCl resulted in alteration of C:N ratios in solid phase, likely due to removal of labile organic and inorganic C- and N-containing compounds, while elevating the HCl concentration did not further change the C:N ratios. Furthermore, sample pretreatment increased the solubility of carbohydrates and proteins in DMSO-d(6), enabling the detection of NMR resonances from certain structural units of carbohydrates (e.g. anomeric O2CH) and proteins (e.g. CH alpha in amino acids). Both attenuation of the paramagnetic matrix as well as art enhanced solubility of carbohydrate and protein fractions of the samples in DMSO-d(6) solvent contributed to an improved molecular characterization of anaerobic digester samples by solution-state NMR analysis. 

  • 177. Zbornikova, Eva
    et al.
    Knejzlik, Zdenek
    Hauryliuk, Vasili
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). University of Tartu, Institute of Technology, Tartu,Estonia.
    Krasny, Libor
    Rejman, Dominik
    Analysis of nucleotide pools in bacteria using HPLC-MS in HILIC mode2019In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 205, article id UNSP 120161Article in journal (Refereed)
    Abstract [en]

    Nucleotides, nucleosides and their derivatives are present in all cells at varying concentrations that change with the nutritional, and energetic status of the cell. Precise measurement of the concentrations of these molecules is instrumental for understanding their regulatory effects. Such measurement is challenging due to the inherent instability of these molecules and, despite many decades of research, the reported values differ widely. Here, we present a comprehensive and easy-to-use approach for determination of the intracellular concentrations of > 25 target molecular species. The approach uses rapid filtration and cold acidic extraction followed by high performance liquid chromatography (HPLC) in the hydrophilic interaction liquid chromatography (HILIC) mode using zwitterionic columns coupled with UV and MS detectors. The method reliably detects and quantifies all the analytes expected to be observed in the bacterial cell and paves the way for future studies correlating their concentrations with biological effects.

  • 178. Zhan, Xuejia
    et al.
    Hu, Guangzhi
    Umeå University, Faculty of Science and Technology, Department of Physics. Laboratory of Environmental Science and Technology, The Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi, People’s Republic of China .
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zhan, Shenshan
    Xu, Hanchu
    Zhou, Pei
    Electrochemical aptasensor for tetracycline using a screen-printed carbon electrode modified with an alginate film containing reduced graphene oxide and magnetite (Fe3O4) nanoparticles2016In: Microchimica Acta, ISSN 0026-3672, E-ISSN 1436-5073, Vol. 183, no 2, p. 723-729Article in journal (Refereed)
    Abstract [en]

    The authors describe a label-free electrochemical aptasensor for tetracycline (TET). The TET-binding aptamer was immobilized on a composite consisting of reduced graphene oxide, magnetite (Fe3O4) and sodium alginate, and this material was used to modify the surface of a screen-printed carbon electrode (SPCE). Cyclic voltammetry was carried out to characterize the single steps in the preparation of the modified electrode and to optimize the conditions for detection. Differential pulse voltammetry (DPV) was then used to monitor the interaction between aptamer and TET by applying the electrochemical probe thionine. Under optimal conditions, TET can be quantified by DPV in the 1 nM to 5 mu M concentration range, with a detection limit as low as 0.6 nM (at an S/N ratio of 3). The method is rapid, cost-efficient, highly sensitive and specific, and therefore is considered to be a viable platform for TET analysis in food, environmental, and clinical samples.

  • 179. Zhan, Xuejia
    et al.
    Hu, Guangzhi
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Zhang, Dongwei
    Zhou, Pei
    A Label-Free Electrochemical Aptasensor for the Rapid Detection of Tetracycline Based on Ordered Mesoporous Carbon-Fe3O42018In: Australian journal of chemistry (Print), ISSN 0004-9425, E-ISSN 1445-0038, Vol. 71, no 2-3, p. 170-176Article in journal (Refereed)
    Abstract [en]

    A novel aptasensor based on a tetracycline (TET) aptamer immobilized by physical adsorption on an ordered mesoporous carbon-Fe3O4 (OMC-Fe3O4)-modified screen-printed electrode surface was successfully fabricated. OMC-Fe3O4 was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The modification procedure of the aptasensor was characterized by cyclic voltammetry. Interaction between the TET aptamer and target was determined by differential pulse voltammetry. Under optimal conditions, the proposed aptasensor exhibited good electrochemical sensitivity to TET in a concentration range of 5 nM to 10 μM, with a detection limit of 0.8 nM (S/N =3D 3). This aptasensor exhibited satisfactory specificity, reproducibility, and stability.

  • 180. Zhang, Qi
    et al.
    Wang, Guangji
    Du, Yu
    Zhu, Lingling
    Jiye, A
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    GC/MS analysis of the rat urine for metabonomic research2007In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 854, no 1-2, p. 20-25Article in journal (Refereed)
    Abstract [en]

    In this paper, an optimized protocol was established and validated for the metabonomic profiling in rat urine using GC/MS. The urine samples were extracted by methanol after treatment with urease to remove excessive urea, then the resulted supernatant was dried, methoximated, trimethylsilylated, and analyzed by GC/MS. Forty-nine endogenous metabolites were separated and identified in GC/MS chromatogram, of which 26 identified compounds were selected for quantitative analysis to evaluate the linearity, precision, and sensitivity of the method. It showed good linearity between mass spectrometry responses and relative concentrations of the 26 endogenous compounds over the range from 0.063 to 1.000(v/v, urine/urine+ water) and satisfactory reproducibility with intra-day and inter-days precision values all below 15%. The metabonomic profiling method based on GC/MS was successfully applied to urine samples from hyperlipidemia model rats. Obviously, separated clustering of model rats and the control rats were shown by principal components analysis (PCA); time-dependent metabonomic modification was detected as well. It was suggested that metabonomic profiling based on GC/MS be a robust method for urine samples.

  • 181.
    Åkerblom, Staffan
    et al.
    Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Bishop, Kevin
    Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lambertsson, Lars
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eriksson, Tobias
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Nilsson, Mats B.
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Significant interaction effects from sulfate deposition and climate on sulfur concentrations constitute major controls on methylmercury production in peatlands2013In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 102, p. 1-11Article in journal (Refereed)
    Abstract [en]

    Transformation of inorganic mercury (Hg) to methyl mercury (MeHg) in peatlands is a key process in making boreal catchments a source of MeHg to freshwater ecosystems. Due to the importance of sulfur-reducing bacteria (SRB) for this process, past atmospheric deposition of sulfate (SO42-) may have increased net terrestrial Hg methylation. A long-term (14-year) factorial design field experiment was used to investigate the effect of enhanced SO42- deposition and raised temperature using a greenhouse (GH) treatment (air temperature similar to+4 degrees C; soil temperature 20 cm below mire surface similar to+2 degrees C) on sulfur (S) turnover, net Hg methylation, MeHg and total Hg concentrations in a boreal mire in northern Sweden. Of the SO42--S added during 14 years, 50% was retained in the plots without GH treatment while the combination of SO42- addition and GH treatment resulted in 15% S retention. The addition of SO42- (7-fold ambient SO42--deposition) increased (p < 0.05) the net Hg methylation (200%) as well as the store of S (150%) and MeHg (120%) in the peat. A combination of enhanced SO42- deposition and GH treatment decreased both the net Hg methylation rate constant (0.018 +/- 0.006 d(-1)) and MeHg content (1.2 +/- 0.2 ng g(-1) dry weight (dw)) relative to the sites with enhanced SO42- deposition without GH treatment (0.065 +/- 0.013 d(-1) and 3.7 +/- 0.6 ng g(-1) dw, respectively). The concentration of Hg in the peat declined (p < 0.05) in response to experimental addition of SO42-. Despite the decrease in Hg in response to SO42- deposition, these plots had the highest amounts of MeHg as well as the highest Hg methylation rate constants. This indicates that the concentration of S is more important than the concentration of Hg for the production of MeHg in this boreal landscape. These results also show that long-term chronic SO42- deposition at rates similar to those found in polluted areas of Europe and North America increase the capacity of wetlands to methylate Hg and store MeHg, which can ultimately be released to streams and lakes. This study also, for the first time, indicates that the enhancing effect of SO42- on the production of MeHg might be counteracted by increased temperature. 

  • 182.
    Östman, Marcus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Antimicrobials in sewage treatment plants: occurrence, fate and resistance2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The World Health Organization (WHO) has identified antibiotic resistance as a major threat to human health. The environment has been suggested to play an important role in the emergence of antibiotic resistant bacteria. The external environment can act as a source of resistance genes that could potentially be transferred into human pathogens. It is also an important route for the dissemination of antibiotic resistance genes and bacteria. Sewage treatment plants (STPs) are among the most important routes by which antibiotics and antibiotic resistance genes enter the environment. It has been suggested that STPs are hotspots for the development of antibiotic resistance because they contain relatively high concentrations of antibiotics as well as both human and environmental bacteria. Further complicating matters, there is evidence that other substances with antimicrobial properties, such as biocides and metals, can cause antibiotic resistance due to co- and cross-resistance.

    This thesis contributes new knowledge on the concentrations, mass flows, and removal efficiencies of antimicrobials in STPs and their connections to the emergence of antibiotic resistance. Paper I presents data on the levels of 40 different antimicrobials in the incoming wastewater, treated effluent, and digested sludge of eleven different STPs. Although not previously detected in STPs, chlorhexidine is shown to be ubiquitous in such plants. In Paper II, mass flows and removal efficiencies are calculated for eleven antimicrobials over various treatment steps in three STPs, showing that polar antimicrobials were inefficiently removed from the wastewater. In Paper III, the minimum selective concentration (MSC) for the antibiotic tetracycline was determined in a complex bacterial aquatic biofilm using both phenotypic and genotypic endpoints. It was found that 10 µg/L selected for phenotypic resistance, and 1 µg/L selected for certain resistance genes. Paper VI used metagenomics to determine whether there is selection for antibiotic-resistant bacteria in STPs and whether the extent of this selection can be correlated to the concentrations of antimicrobial compounds. No clear evidence for selection was identified. Paper V evaluates advanced wastewater treatment techniques for removing antimicrobial compounds using ozonation and granular activated carbon (GAC). The identity of the GAC material was found to strongly affect removal efficiency, and GAC was more efficient than ozonation for most compounds at the tested concentrations.

  • 183.
    Östman, Marcus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Björlenius, Berndt
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Effect of full-scale ozonation and pilot-scale granular activated carbon on the removal of biocides, antimycotics and antibiotics in a sewage treatment plant2019In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 649, p. 1117-1123Article in journal (Refereed)
    Abstract [en]

    Several micropollutants show low removal efficiencies in conventional sewage treatment plants, and therefore enter the aquatic environment. To reduce the levels of micropollutants in sewage effluent, and thereby the effects on biota, a number of extra treatment steps are currently being evaluated. Two such techniques are ozonation and adsorption onto activated carbon. In this study, we investigated the efficiency of Sweden's first full-scale ozonation treatment plant at removing a number of antibiotics, antimycotics and biocides. The effect of adding granular activated carbon (GAC) on a pilot scale and pilot-scale ozonation were also evaluated. The conventional treatment (13,000 PE) with the add-on of full-scale ozonation (0.55 g O3/g Total organic carbon (TOC)) was able to remove most of the studied compounds (>90%), except for benzotriazoles and fluconazole (<50%). Adsorption on GAC on a pilot scale showed a higher removal efficiency than ozonation (>80% for all studied compounds). Three types of GAC were evaluated and shown to have different removal efficiencies. In particular, the GAC with the smallest particle sizes exhibited the highest removal efficiency. The results demonstrate that it is important to select an appropriate type of carbon to achieve the removal goal for specific target compounds.

  • 184.
    Östman, Marcus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lindberg, Richard H.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fick, Jerker
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Screening of biocides, metals and antibiotics in Swedish sewage sludge and wastewater2017In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 115, p. 318-328Article in journal (Refereed)
    Abstract [en]

    Incoming sewage water, treated effluent and digested sludge were collected from 11 Swedish sewage treatment plants (STPs) on 3 different days. Analytical protocols were established for a large number of compounds (47) with antimicrobial properties and the collected samples were then screened for the presence of these selected substances. Liquid chromatography tandem mass spectrometry (LC-MS/MS) and inductively coupled plasma mass spectrometry (ICP-MS) were used to analyse the samples. Thirty organic compounds and 10 metals were detected above their respective detection limit. Quaternary ammonium compounds were the most abundant substances in the particulate phases with levels up to 370 μg/g and benzotriazoles were the most common in the aqueous phases with levels up to 24 μg/L. Several compounds with no, or very limited, previously reported data were detected in this study, including chlorhexidine, hexadecylpyridinium chloride and 10-benzalkonium chloride. Some of these were both frequently detected (>60% detection frequency) and found in high levels (up to 19 μg/g d.w. sludge). This study gives a comprehensive overview of the presence in Swedish STPs of a number of antimicrobial substances, providing crucial information in designing relevant studies on potential microbial co- and cross resistance development between antibiotics, biocides, and metals in the sewage system.

  • 185.
    Östman, Marcus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Näsström, Elin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Construction of a Labview controlled pyrolysis unit for coupling to a Pyrola 85 pyrolysis chamber2012Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Pyrolysis is the process of molecular decomposition in an inert environment using heat. It is possible to fragment large molecules, such as polymers, by pyrolysis and separate the fragments directly in a GC. This makes it possible to form complex sample fingerprints that can be used in various applications, for example in forensic science.

    In this project, a malfunctioning Pyrola 85 pyrolysis unit was fixed by measuring the voltage signals from the photo diode during pyrolysis in a Labview program. With the Labview program, a partly manual filament temperature calibration procedure was developed, as replacement for the non-working automatic calibration procedure. The functioning pyrolysis unit was then installed on a GC/MS in the National University of Science, Ho Chi Minh City, Vietnam. Plant samples were analysed with the Pyrolysis-GC/MS system as a test of the system, resulting in pyrograms with a few identifiable peaks. However, both pyrolysis and GC/MS settings needs further investigation to optimize the analysis.

    In Sweden, a Labview controlled Pyrolysis unit was constructed to investigate the possibility of improving certain functions of the original control unit. A proposed Labview program and circuit boards were constructed and partially evaluated. The accuracy and precision of the pulses from the Labview program was

  • 186. Šetková, Lucie
    et al.
    Hajšlová, Jana
    Bergqvist, Per-Anders
    Umeå University.
    Kocourek, Vladimír
    Kazda, Radek
    Suchan, Petr
    Fast isolation of hydrophobic organic environmental contaminants from exposed semipermeable membrane devices (SPMDs) prior to GC analysis2005In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1092, no 2, p. 170-81Article in journal (Refereed)
    Abstract [en]

    Semipermeable membrane devices (SPMD) represent a passive sampling technology that is becoming widely used for monitoring of surface waters pollution. While “classic” procedures employ dialysis to recover target compounds from exposed SPMDs, in the present study analytes were isolated from cut membrane together with sequestering medium (triolein) using hexane as an extraction solvent. This approach allowed us to reduce the time needed for accomplishment of isolation step from 48 h to only 1 h. Automated gel permeation chromatography (GPC) clean-up is employed in the following step to separate triolein from analytes fraction. Musk compounds (MCs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs) and several other persistent organochlorine compounds (OCs) were determined in the respective fraction by GC method employing selective detectors (MSD, ECD). As shown in a series of analyses of SPMDs deployed in various aquatic ecosystems, high recoveries and good repeatability of results together with a possibility to obtain the information on the pollution of sampling site at the day of sample arrival to laboratory make this newly implemented procedure an interesting alternative to time consuming dialysis.

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