Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 581-591 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1988), S. 121-129 
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...