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  • Wiley-Blackwell  (15)
  • Springer  (5)
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  • 1
    Electronic Resource
    Electronic Resource
    On the use of laser microprobe mass spectrometry for the analysis of organic biomolecules (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 581-591 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser microprobe mass spectrometry has been applied to a variety of organic polyfunctional molecules, covering a wide range of polarity and mass spectrometric behaviour. The technique apparently combines desorption under relatively soft conditions with extensive fragmentation and hence allows much structural information from intactly released thermolabiles to be obtained. The mass spectra appear unfamiliar in comparison to conventional techniques. Interpretation is attempted in a purely empirical way by means of the evidence from our database and tentative hypotheses to rationalize the desorption and ionization by laser microbeam irradiation of organic solids. Selected examples are presented to illustrate the potential and limitations of the method in the field of biomolecules, such as pyridoxine and pyridoxal phosphate, nucleosides, nucleotides and related analogues, drugs and the corresponding N-oxides.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200180813
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  • 2
    Electronic Resource
    Electronic Resource
    Intelligent software for chemical analysis lutgarde M. C. Buydens and Peter J. Schoenmakers (eds), Elsevier, Amsterdam, 1993, ISBN 0-444-89207-9, 366 pp., hardcover Df1350.00 (us$200.00) (1995)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 9 (1995), S. 432-433 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180090510
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  • 3
    Electronic Resource
    Electronic Resource
    In-depth limitation of the Lamma 500 for the in situ localization of organic compounds in biological embedded tissue samples (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1988), S. 113-119 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The objective of this study was exploration of the potential, offered by the laser microprobe mass spectrometer (LAMMA), for the in situ localization of organic targets in embedded tissues by means of structurally relevant ions. A series of model systems was designed to evaluate stepwise the analytical problems involved. A preliminary screening pointed to the position of the target in comparison to the actual sample surface as a determining parameter. Refined simulations were carried out with sandwich samples, consisting of an epon carrier (thickness 1 μm), coated with microcrystalline targets and covered with a layer between 5 and 50 nm of different materials (epon, carbon, formvar). In addition to a stimulated conversion of molecular into fragment ions, the presence of a barrier leads to a drastic loss of sensitivity (20-50 x) and unacceptable degradation of the mass spectrometric quality (resolution, calibration).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200160120
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  • 4
    Electronic Resource
    Electronic Resource
    Structural characterization of drugs and oxygenated metabolites by laser microprobe mass spectrometry (LAMMA) (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1988), S. 121-129 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser microprobe mass analysis (LAMMA) was used for the structural characterization of polyfunctional drugs and their oxygenated metabolites, in particular the N-oxides. The spectra usually yield the molecular weight as well as intense fragments. The structural information is characteristically distributed between the positive and negative ions. To rationalize the unfamiliar fragmentation, tentative pathways are introduced. Key elements are the formation of odd-electron molecular (and fragment) ions, the correlation between cations and anions, as well as the three-dimensional representation of structures. The combination of mild desorption and abundant fragmentation makes LAMMA a valuable tool in the study of N-oxides.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200160121
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  • 5
    Electronic Resource
    Electronic Resource
    An in-depth study of energy-dispersive x-ray spectra (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 9 (1980), S. 126-133 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A detailed study of energy-dispersive X-ray spectra is undertaken. Considerable attention is given to a method for a systematic and accurate description of the K and L spectra; a digital correction for the peak profile is evaluated. The following second order effects and spectral artefacts are investigated: radiative Auger transitions, spectral background components, Raman scattering of X-rays, silicon escape, fluorescence of the detector materials, and sum peaks.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300090308
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  • 6
    Electronic Resource
    Electronic Resource
    Evaluation of a practical background calculation method in X-ray energy analysis (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 5 (1976), S. 123-128 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The background beneath the fluorescence lines of energy dispersive X-ray spectra obtained with a molybdenam secondary target tube-excited system can be obtained from the intensities of the coherently and incoherently scattered radiation. The background intensity at a particular energy is equal to the product of a proportionality factor multiplied by the incoherently scattered radiation intensity, plus another proportionality factor multiplied by the coherently scattered radiation intensity. The proportionality factors are determined from measurements of a number of molybdenum-loaded cellulose filters.The proposed procedure provides accurate results for the analysis of complex X-ray spectra of thin samples of varying composition.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300050304
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of X-ray spectra by iterative least squares (AXIL): New developmentsPresented at the European Conference on EDXRS, Budapest, Hungary, May 30-June 3, 1994 (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 23 (1994), S. 278-285 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The functionality of the computer package AXIL (Analysis of X-ray spectra by Iterative Least squares), suitable for the evaluation of energy-dispersive X-ray spectra, has been extended in a number of ways. First, a background modelling algorithm, based on the use of mutually orthogonal polynomials was introduced to replace the linear or exponential polynomials employed previously. Second, the Gaussian photopeak model employed in previous versions of the program was extended to include the non-Gaussian parts of the characteristic peaks and related background contributions. Both innovations are shown to improve the performance of the spectrum evaluation procedure. Third, the user-friendliness of the evaluation program was enhanced (a) by allowing a PC plug-in MCA card to be directly controlled from within the program and (b) by extending the command-interface to allow for repeated execution of series of commands by means of control loops. A brief description of these changes is given; as an application, the accurate evaluation of micro-XRF images is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300230609
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  • 8
    Electronic Resource
    Electronic Resource
    Structural characterization of organic molecules by negative ions in laser microprobe mass spectrometry. Part 2 - Salts (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 24 (1989), S. 797-806 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser microprobe mass spectrometry (LMMS) has been applied systematically to a variety of organic polyfunctional molecules, covering a wide range of structures and polarities. The microprobe generally offers a combination of desorption under relatively mild conditions with abundant fragmentation. We attempted an empirical approach by tentative hypotheses about desorption and ionization in LMMS to consistently rationalize the detected fragments. The complementary nature of structural data, carried by positive and negative ions, is characteristic for LMMS results of non-ionic compounds. The analysis of salts represents, traditionally, an ultimate test case for soft methods in organic mass spectrometry. Hence, by a selected series of compounds, we have tried to assess to which extent the presence of preformed ions becomes an asset for LMMS analysis and affects the amount, the accessibility or the distribution of organic information between positive and negative fragments.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210240913
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  • 9
    Electronic Resource
    Electronic Resource
    Linear and non-linear peak fitting in energy-dispersive X-ray fluorescence (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 8 (1979), S. 104-109 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Linear and non-linear least-squares fitting procedures are compared in their ability to resolve X-ray fluorescence spectra obtained with Si(Li) detectors. It is shown, by repeated analysis of synthetic and real X-ray spectra, that non-linear least-squares fitting programs which take into account the relation between peak positions and widths on the one hand and X-ray energies on the other hand, and moreover impose limitations upon the fitting parameters, represent a definite advantage over the linear least-squares fitting method. Only for spectrometers having an extremely high stability with time and counting rate does the linear fitting procedure yield accurate results.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300080305
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  • 10
    Electronic Resource
    Electronic Resource
    Calibration of tube excited energy-dispersive X-ray spectrometers with thin film standards and with fundamental constants (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 10 (1981), S. 64-68 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The calibration of an energy-dispersive X-ray spectrometer is calculated from published physical constants, when the geometry factor of secondary target, sample, detector is obtained experimentally and when the detection efficiency of the Si(Li) detector is calculated from such experimentally derived parameters as the thickness of cryostat window, gold surface barrier contact and silicon dead layer. The results are compared with calibrations obtained experimentally from commercial single element thin film standards obtained by vacuum evaporation and multielement standards obtained by incorporating known amounts of the elements into a thin film polymer. The results obtained from fundamental parameters agree with the experimental data to within 5-6%.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300100206
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