umu.sePublications
Change search
Refine search result
1 - 10 of 10
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Ekman, Jenny
    et al.
    National Institute for Working Life, Umeå.
    Levin, Jan-Olof
    National Institute for Working Life, Umeå.
    Lindahl, Roger
    National Institute for Working Life, Umeå.
    Sundgren, Margit
    National Institute for Working Life, Umeå.
    Ostin, Anders
    National Institute for Working Life, Umeå.
    Comparison of sampling methods for 1,6-hexamethylene diisocyanate, (HDI) in a commercial spray box2002In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 127, no 1, p. 169-173Article in journal (Refereed)
    Abstract [en]

    In this study three different types of samplers for the determination of 1,6-hexamethylene diisocyanate in air were compared. The experimental set up was a simulation of real life conditions with spray painting operations performed inside a commercial, full sized, spray box. The sampling methods were 1-(2-methoxyphenyl)-piperazine impregnated on glass fibre filter, and the same reagent in impinger, and also dibutylamine in impinger. All analyses were performed by LC-MS-MS. The determined concentrations varied between 20 and 90 microg m(-3) with relative standard deviations from 7 to 17% for each method. No significant difference was found between the three methods using ANOVA with a significance level of alpha = 0.05.

  • 2.
    Hagenbjörk-Gustafsson, Annika
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. National Institute for Working Life, Programme for Chemical Exposure Assessment, Umeå.
    Lindahl, Roger
    Umeå University, Faculty of Science and Technology, Department of Chemistry. National Institute for Working Life, Programme for Chemical Exposure Assessment, Umeå.
    Levin, Jan-Olof
    Umeå University, Faculty of Science and Technology, Department of Chemistry. National Institute for Working Life, Programme for Chemical Exposure Assessment, Umeå.
    Karlsson, Doris
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Validation of the Willems badge diffusive sampler for nitrogen dioxide determinations in occupational environments2002In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 127, no 1, p. 163-168Article in journal (Refereed)
    Abstract [en]

    The Willems badge, a diffusive sampler for nitrogen dioxide, has previously been validated for ambient air measurements. This paper describes the laboratory and field validation of the Willems badge for personal sampling under working environment conditions. The mean sampling rate in the laboratory tests was 46 ml min(-1), with an RSD of 12%. No statistically significant effects on sampling rate of the sampling time, concentration of NO2 or relative humidity were found. A slightly decreased sampling rate was observed at low wind velocity. This was also confirmed during static sampling, which makes the sampler less appropriate for static sampling indoors. No back diffusion was observed. Storage of the samplers for two weeks before or after exposure did not affect the sampling rate. Our analysis is based on a modified colorimetric method, performed by FIA (flow injection analysis). This technique was compared to ion chromatography analysis. The use of ion chromatography lowered the detection limit from 11 to 2 microg m(-3) for an 8 h sample, and furthermore enabled the detection of other anions. In conclusion, the diffusive sampler was found to perform well for personal measurements in industrial environments.

  • 3.
    Jonsson, Pär
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bruce, Stephen J
    Moritz, Thomas
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjöström, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Plumb, Robert
    Granger, Jennifer
    Maibaum, Elaine
    Nicholson, Jeremy K
    Holmes, Elaine
    Antti, Henrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Extraction, interpretation and validation of information for comparing samples in metabolic LC/MS data sets2005In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 130, no 5, p. 701-707Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    LC/MS is an analytical technique that, due to its high sensitivity, has become increasingly popular for the generation of metabolic signatures in biological samples and for the building of metabolic data bases. However, to be able to create robust and interpretable ( transparent) multivariate models for the comparison of many samples, the data must fulfil certain specific criteria: (i) that each sample is characterized by the same number of variables, (ii) that each of these variables is represented across all observations, and (iii) that a variable in one sample has the same biological meaning or represents the same metabolite in all other samples. In addition, the obtained models must have the ability to make predictions of, e. g. related and independent samples characterized accordingly to the model samples. This method involves the construction of a representative data set, including automatic peak detection, alignment, setting of retention time windows, summing in the chromatographic dimension and data compression by means of alternating regression, where the relevant metabolic variation is retained for further modelling using multivariate analysis. This approach has the advantage of allowing the comparison of large numbers of samples based on their LC/MS metabolic profiles, but also of creating a means for the interpretation of the investigated biological system. This includes finding relevant systematic patterns among samples, identifying influential variables, verifying the findings in the raw data, and finally using the models for predictions. The presented strategy was here applied to a population study using urine samples from two cohorts, Shanxi (People's Republic of China) and Honolulu ( USA). The results showed that the evaluation of the extracted information data using partial least square discriminant analysis (PLS-DA) provided a robust, predictive and transparent model for the metabolic differences between the two populations. The presented findings suggest that this is a general approach for data handling, analysis, and evaluation of large metabolic LC/MS data sets.

  • 4.
    Kumar, Keshav
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Cava, Felipe
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Constraint randomised non-negative factor analysis (CRNNFA): an alternate chemometrics approach for analysing the biochemical data sets2017In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 142, no 11, p. 1916-1928Article in journal (Refereed)
    Abstract [en]

    The present work introduces an alternate chemometrics approach constraint randomised non-negative factor analysis (CRNNFA) for analysing the bioanalytical data sets. The CRNNFA algorithm provides the outputs that are easy to interpret and correlate with the real chromatograms. The CRNNFA algorithm achieves termination when the iteration limit is reached circumventing the premature convergence. Theoretical and computational aspects of the proposed method are also described. The analytical and computational potential of CRNNFA are successfully tested by analysing the complex chromatograms of the peptidoglycan samples belonging to the Alphaproteobacterium members. The obtained results clearly show that CRNNFA can easily trace the compositional variability of the peptidoglycan samples. In summary, the proposed method in general can be a potential alternate approach for analysing the data sets obtained from different analytical and clinical fields.

  • 5.
    Larsson, Tom
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Frech, Wolfgang
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Dybdahl, Björn
    Studies of transport and collection characteristics of gaseous mercury in natural gases using amalgamation and isotope dilution analysis2007In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 132, no 6, p. 579-586Article in journal (Refereed)
    Abstract [en]

    Transport and collection characteristics were studied for gaseous elemental mercury (Hg0(g)) in natural gases using newly developed methodology based on amalgamation, isotope dilution with permeation tubes and inductively coupled plasma mass spectrometry. The study involved different Au–Pt collection tube designs, tubing materials and gaseous matrices, including air, natural and sales gas, as well as methane and sales gas to which hydrogen sulfide (H2S) had been added. The Hg0(g) capacity of the Au–Pt tubes was determined to 3.5 ± 0.1 µg. Blanks and detection limits of gaseous mercury (Hg(g)) were 58 ± 17 pg m–3 and 50 pg m–3, respectively, for a 60 L sample volume. For the gases tested, added Hg0(g) tracers could be collected with 90% or higher efficiency at flow rates and volumes of up to 10 L min–1 and 100 L, respectively. The collection efficiency was found to be independent of the type of gas tested, even in the presence of H2S. However, for the gases containing H2S, the apparent transport efficiency of added Hg0(g) tracers through stainless steel tubing varied from 50 to 150% upon changing the temperature from 25 to 100 °C. The interaction of stainless steel with Hg0(g) leading to either a sink, or source of Hg, was not observed in the absence of H2S, nor was it observed for PTFE tubing in the presence of H2S. These observations raise questions about the applicability of currently used sampling procedures for determination of Hg(g) in H2S rich natural gases, including the 6978-2 ISO standard method, in which stainless steel is a prescribed material for tubing and valves of the sampling apparatus.

  • 6.
    Lindahl, R
    et al.
    National Institute for Working Life, Umeå.
    Wästerby, A
    National Institute for Working Life, Umeå.
    Levin, Jan-Olof
    National Institute for Working Life, Umeå.
    Determination of morpholine in air by derivatisation with 1-naphthylisothiocyanate and HPLC analysis2001In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 126, no 2, p. 152-154Article in journal (Refereed)
    Abstract [en]

    A method for the determination of morpholine in air was developed. Samples were collected with adsorbent tubes containing XAD-2 resin coated with 1-naphthylisothiocyanate (NIT). The thiourea derivative formed was subsequently desorbed with acetonitrile and analysed by HPLC with UV detection. The recovery after gas phase spiking with morpholine (2.2-1570 micrograms) was 91% (86-100%) with a relative standard deviation of 5.5%. No effect on recovery from relative humidity or amount of morpholine was seen. The lowest level tested corresponded to 7 mg m-3 (1/10 threshold limit value) for a 15 min sampling period with a sampling rate of 20 ml min-1. Exposed NIT-coated XAD-2 tubes were stable at room temperature for at least 2 weeks.

  • 7.
    Nyberg, Morgan
    et al.
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Ramser, Kerstin
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Lindahl, Olof A.
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Optical fibre probe NIR Raman measurements in ambient light and in combination with a tactile resonance sensor for possible cancer detection2013In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 138, no 14, p. 4029-4034Article in journal (Refereed)
    Abstract [en]

    First measurements on a combined instrument with a thin fibre optic Raman probe mounted inside a hollow tactile resonance sensor have been performed in ambient light on porcine tissue. The ambient fluorescent light was removed successfully from the spectra. The stiffness and the biomolecular composition of the tissue were analysed.

  • 8.
    Qvarnström, Johhanna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tu, Qiang
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Frech, Wolfgang
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lüdke, C.
    Flow injection-liquid chromatography-cold vapour atomic absorption spectrometry for rapid determination of methyl- and inorganic mercury2000In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 125, no 6, p. 1193-1197Article in journal (Refereed)
    Abstract [en]

    A previously described system for determining low concentrations of mercury species in environmental samples using flow injection high-performance liquid chromatography cold vapour atomic absorption spectrometry (FI-HPLC-CVAAS) has been further developed with respect to time of analysis, long term signal stability, memory effects, detection limits, and environmental friendliness. Methyl and inorganic mercury were determined without pre-treatment in brackish water and in digested biological certified reference materials, DOLT-2 and TORT-2. Results were compared with those obtained by gas chromatography microwave-induced plasma atomic emission spectroscopy (GC-MIP-AES) using either butylation with a Grignard reagent or ethylation with sodium tetraethylborate. With the FI-HPLC-CVAAS system, absolute detection limits are 1.7 pg and 3.4 pg for methyl and inorganic mercury, respectively. Mercury species in a sample can be determined at the 0.4 ng l−1 level within 5 min. For lower concentrations the time for analysis has to be increased.

  • 9.
    Sandström, K. J. Mattias
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational Medicine. Programme for Chemical Exposure Assessment, National Institute for Working Life, Umeå and Cranfield Biotechnology Centre, Cranfield University, Silsoe, UK.
    Carlson, Rolf
    Department of Chemistry, Faculty of Science, University of Tromsø, Tromsø, Norway.
    Sunesson, Anna-Lena
    Programme for Chemical Exposure Assessment, National Institute for Working Life, Umeå.
    Levin, Jan-Olof
    Programme for Chemical Exposure Assessment, National Institute for Working Life, Umeå.
    Turner, Anthony P. F.
    Cranfield Biotechnology Centre, Cranfield University, Silsoe, UK.
    Multivariate evaluation of factors influencing the performance of a formic acid biosensor for use in air monitoring2001In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 126, no 11, p. 2008-2014Article in journal (Refereed)
    Abstract [en]

    A formic acid biosensor for air monitoring has been evaluated using chemometric methods. Using experimental design eleven factors that could influence the performance of the biosensor were examined. The response matrices consisted of six parameters (steady state currents at three different formic acid concentrations and response rates during changes in formic acid concentrations) describing the performance of the biosensor. The data were evaluated using a combination of principal component analysis (PCA) and multiple linear regression (MLR). To confirm the conclusions from the PCA-MLR partial least squares (PLS) was also used. The most important factor for the biosensor performance was found to be the enzyme concentration. Using the information from the chemometric analyses the optimum operation conditions for the biosensor were determined. The steady state currents were increased by 18–30% and the initial two response rates increased by 47–89% compared with a biosensor that had not been optimised.

  • 10.
    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.

1 - 10 of 10
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf