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  • 1.
    Axelsson, Mikael D.
    et al.
    Luleå University of Technology.
    Rodushkin, Ilya
    Luleå University of Technology. SGAB Analytica, Luleå, Sweden .
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology.
    Multielemental analysis of Mn–Fe nodules by ICP-MS: optimisation of analytical method2002In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 127, no 1, p. 76-82Article in journal (Refereed)
    Abstract [en]

    Two acid digestion procedures (microwave-assisted and room temperature) were developed for the quantitative analysis of ferromanganese nodules by inductively coupled plasma double focusing sector field mass spectrometry (ICP-SFMS). Different compositions of the acid mixture, dilution factors and corrections for spectral interferences were tested. A combination of nitric, hydrochloric and hydrofluoric acids is necessary for complete sample digestion, with lowest acid to sample ratios (v/m) of 15 and 1.5. respectively, for the last two acids. Sample dilution factors higher than 2 X 104 should be used in order to decrease matrix effects and provide robust long-term instrumental operation. In spite of high dilution. method detection limits in the sub-mug g(-1) range were obtained for 54 out of 71 elements tested. due to the high detection capability of ICP-SFMS, as well as the special care taken to ensure the purity of reagents, to clean the instrument sample introduction system and to minimise sample handling. Owing to the presence of unresolved (at the resolution available) spectral interferences, accurate determination of Au, Hg, Os, Pd, Re and Rh is impossible without matrix separation. The accuracy of the entire analytical method was tested by the analysis of two nodule reference materials. The results generated agreed to within +/-2% for about 10, within +/-10% for more than 40 and within +/-20% for about 50 of 53 elements for which certified, recommended or literature values are available. A precision better than 3%, expressed as the between-digestion relative standard deviation (n=4). was obtained for the majority of elements, except in cases limited by low analyte concentrations

  • 2. Candefjord, Stefan
    et al.
    Ramser, Kerstin
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Lindahl, Olof
    Effects of snap-freezing and near-infrared laser illumination on porcine prostate tissue as measured by Raman spectroscopy2009In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 134, no 9, p. 1815-1821Article in journal (Refereed)
    Abstract [en]

    Most Raman spectroscopic studies on tissue are performed in vitro. To assure that the results are applicable to in vivo examinations, preparation protocols and measurement procedures of tissue for in vitro studies should preserve tissue characteristics close to the native state. This study had two aims. The first was to elucidate if photoinduced effects arise during 5 minutes' continuous illumination of tissue with an 830 nm laser at an irradiance of 3 × 1010 W/m2. The second was to investigate the effects of snap-freezing of porcine prostate tissue in liquid nitrogen and subsequent storage at -80 °C, by means of multivariate analysis. 830 nm laser illumination of the specified irradiance did not affect the Raman spectra. A decrease of the spectral background was observed, likely due to photobleaching of tissue fluorophores. Snap-freezing and subsequent storage at -80 °C gave rise to subtle but significant alterations in Raman spectra, most likely related to changes in the protein conformations

  • 3.
    Emteborg, Håkan
    et al.
    Department of Analytical Chemistry, Umeå University, Umeå, Sweden.
    Björklund, Erland
    Department of Analytical Chemistry, Lund University, Lund, Sweden.
    Ödman, Fredrik
    Luleå University of Technology.
    Karlsson, Lars
    Department of Analytical Chemistry, Lund University, Lund, Sweden.
    Mathiasson, Lennart
    Department of Analytical Chemistry, Lund University, Lund, Sweden.
    Frech, Wolfgang
    Department of Analytical Chemistry, Umeå University, Umeå, Sweden.
    Baxter, Douglas C.
    Department of Analytical Chemistry, Umeå University, Umeå, Sweden.
    Determination of methylmercury in sediments using supercritical fluid extraction and gas chromatography coupled with microwave-induced plasma atomic emission spectrometry1996In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 121, no 1, p. 19-29Article in journal (Refereed)
    Abstract [en]

    A method employing supercritical fluid extraction (SFE) and GC coupled with microwave-induced plasma atomic emission spectrometry (MIP–AES) is presented for the determination of methylmercury in sediments. Butylmagnesium chloride was used to derivatize the target compound to butylmethylmercury which is amenable to GC. Using a commercially available reference sediment (PACS-1, National Research Council of Canada) as the model sample, a factorial design was utilized to investigate the effect of three variables; density, temperature and flow rate, on the extraction efficiency. An extraction efficiency of 49 ± 0.5% could be obtained for a 37.5 min dynamic extraction, corresponding to 25 thimble volumes of supercritical CO2, and using purified support sand. Studies on the efficacy of SFE for another sediment matrix as a function of time have also been undertaken. Repeated pressure reductions in combination with support sand were found to increase the extraction efficiency of methylmercury from PACS-1 but not from a sediment issued by the Community Bureau of Reference (BCR) as part of an interlaboratory comparison. For PACS-1 this resulted in an increase in the average extraction efficiency to 96% for duplicate determinations following 50 thimble volume sweeps. Distillation was used as a reference method for isolation of methylmercury from sediments. Parallel extractions of the BCR sediment, using GC–MIP–AES for the final determination, gave results that were in good agreement and corresponded well with data submitted during the intercomparison exercise. The detection limit for the methylmercury in sediment using the described SFE GC–MIP–AES method is estimated to be 0.1 ng g–1 based on a 20 µl injection, 0.5 g of sample and three times the blank level. It is proposed that the co-extracted sulfur from the sediment mediates the transport of methylmercury and, to some extent, inorganic mercury from the sediments. This is supported by the strong correlation between the concentrations of butylmethylmercury and dibutylsulfide found in the toluene extract. Using a stable isotope tracer, 199Hg, and ICP-MS, evidence for the spurious formation of methylmercury during SFE under certain conditions is also presented.

  • 4.
    Johansson, Ursula
    et al.
    Luleå University of Technology.
    Holmgren, Allan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Forsling, Willis
    Luleå University of Technology.
    Frost, Ray L.
    Centre for Instrumental and Developmental Chemistry, Queensland University of Technology, Brisbane, Queensland, Australia.
    Isotopic exchange of kaolinite hydroxyl protons: a diffuse reflectance infrared Fourier transform spectroscopy study1998In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 123, no 4, p. 641-645Article in journal (Refereed)
    Abstract [en]

    Specific surface reactions on kaolinite were investigated by deuterium exchange of the hydroxyl protons of kaolinite, The kaolinite samples were reacted with deuterium oxide for 48 h and 2.5 and 5 weeks, at various pH values (3, natural and 8) and at different temperatures (ambient, and 30, 60 and 100 degrees C), Analyses were performed using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The spectral results show that it is very difficult at room temperature to exchange the hydroxyl protons isotopically with deuterons at the surface of kaolinite, The temperature and the reaction time must be increased for successful exchange. It was found that the most suitable temperature for isotopic exchange was 60 degrees C. The pH did not significantly influence the deuteration, Only at high pH were changes of the OD bands in the DRIFT spectra observed, This study shows that it is possible to deuterate kaolinite without using intercalation. All three types of hydroxyl protons from the inner, inner surface and edge were exchanged.

  • 5.
    Liu, Wenxin
    et al.
    Luleå University of Technology. SKLEAC, Research Center for Eco-Environmental Sciences, Academia Sinica, Beijing, China.
    Sun, Zhongxi
    Luleå University of Technology.
    Ranheimer, Maine
    Luleå University of Technology.
    Forsling, Willis
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Sustainable Process Engineering.
    Tang, Hongxiao
    SKLEAC, Research Center for Eco-Environmental Sciences, Academia Sinica, Beijing, China.
    A flexible method of carbonate determination using an automatic gas analyzer equipped with an FTIR photoacoustic measurement chamber1999In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 124, no 3, p. 361-365Article in journal (Refereed)
    Abstract [en]

    A Fourier transform infrared spectrometer was employed to determine automatically the total inorganic carbonate (TIC) in solids and waters, based on active photoacoustic absorption of infrared light by carbon dioxide. A 2.0 l reactor, connected to the spectrometer, is immersed in water-bath at 20 °C. After purging with pure N2, 5 ml of 0.5 mol l–1 HClO4 are injected into 50 ml of solid suspension or solution with continuous stirring. The specific absorption of infrared light by the CO2 evolved induces corresponding fluctuations of temperature and pressure in a measurement chamber. Accordingly, photoacoustic signals, with frequencies dependent on the absorbed wavelengths, are generated and measured by the chamber microphones in the form of an absorption spectrum and concentration. For solids, the method exhibits a linear response up to 120 mg of CaCO3 with a detection limit of 0.02 mg; in the case of waters, these figures of merit are 36.4 mmol l–1 and 3 µmol l–1 NaHCO3, respectively. Since proton consumption by TIC in clay minerals may commonly influence the evaluation of surface acid–base properties, the methodology was applied to determine TIC in three natural illite samples of different origins. In addition, some potential interferences and modifications of this method are discussed.

  • 6.
    Nyberg, Morgan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Ramser, Kerstin
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Lindahl, Olof
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    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.

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