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  • National Institutes of Health (U.S.)  (81)
  • Astronomy  (52)
  • Analytical Chemistry and Spectroscopy  (45)
  • 1
    Electronic Resource
    Electronic Resource
    Laser desorption/fourier transform ion cyclotron resonance mass spectrometry: Digoxin, digitoxin, and their reduced and sugar-hydrolyzed metabolites (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 295-302 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectra of digoxin and digitoxin (the most widely prescribed drugs for treatment of congestive heart failure) and a complete set of their 14 dihydro- and sugar-hydrolyzed metabolites have been obtained via laser desorption/ionization with a Fourier transform ion cyclotron resonance (LD/FT/ICR) mass spectrometer. The most intense peak is typically the pseudomolecular [M + K]+ ion, but fragment ions corresponding to loss of 1--3 sugars and hydroxyls are also observed. LD/FT/ICR mass spectra for all 16 compounds were produced with a single set of sample and spectrometer parameters. No matrix peaks are present. Finally, LD/FT/ICR provides dynamic mass accuracy within ≈5 ppm throughout a mass range of 404 〈 m/z 〈 819.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200150510
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  • 2
    Electronic Resource
    Electronic Resource
    An efficient algorithm for sequencing peptides using fast atom bombardment mass spectral data (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 333-343 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An efficient algorithm is described for sequencing peptides from sequence ions appearing in fast atom bombardment (FAB) and FAB tandem mass spectra. The following features are incorporated in the algorithm. The members of the set of sequence ions are represented by all possible combinations of N- and C-terminal fragment ions. From the known N- and C-terminating groups and molecular weight (MW) of the peptide, the sequence ions are mathematically re-expressed as N-terminal residue ions and arranged in ascending order. The peptide sequence is computed, in a stepwise iterative procedure, from the mass differences between the mathematically re-expressed N-terminal residue ions and the predicted peptide subsequences for the neighboring ions of lower mass. These mass differences correspond to combinations of known amino acid residues which have previously been computed and tabulated, based upon the FAB fragmentation rules for peptides. The algorithm was successfully applied to sequence the following peptides from their respective FAB or FAB tandem mass spectrum: decapeptyl (MW 1310), angiotensin II (MW 1045), and two ‘unknown’ peptides (MW 1227 and 1485, respectively). Two criteria used to predict the correct peptide sequence from among many possibilities are the minimum number of amino acid residues and the maximum fragmentation probability per amino acid residue.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200150606
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  • 3
    Electronic Resource
    Electronic Resource
    Applications of fast atom bombardment mass spectrometry and fast atom bombardment mass spectrometry - mass spectrometry to the maduramicins and other polyether antibiotics (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 29-38 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment mass spectrometry (FAB MS) and fast atom bombardment mass spectrometry-mass spectrometry (FAB MS/MS) were used to study the monovalent glycoside polyether antibiotics maduramicin α, β and δ and the maduramicin α salts, their derivatives and degradation products. Also, representative compounds from three major classes of polyether antibiotics were studied: the monovalent polyethers, nigericin and monensin A, the divalent polyether lasalocid A and the monovalent glycoside polyethers septamycin, BL580 δ, etheromycin and carriomycin. The respective FAB fragment and decomposition ions were correlated with the known structures. The FAB spectra of all the polyethers contained metal-adduct molecular ions. Protonated molecular ions were absent. All the polyethers having a β-hemiketal carboxylic acid group produced an abundant ion, often the base peak of the spectra, 62 daltons less than the corresponding metal-adduct molecular ion. The gas phase mechanism proposed for the formation of this fragment ion is an unusual unimolecular reaction which is initiated by an intramolecular proton transfer from the carboxylic acid to the hydroxy group of the β-hemiketal, and, then followed by the concerted losses of water and carbon dioxide to produce the corresponding polyether olefin.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200140108
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  • 4
    Electronic Resource
    Electronic Resource
    Energy disposal in gas-phase nucleophilic displacement reactions (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 26 (1991), S. 1003-1007 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The partitioning of reaction exothermicity into relative translational energy of the products of gas-phase SN2 (F- + CH3Cl) and nucleophilic aromatic substitution (F- + C6H5Cl) reactions has been investigated using kinetic energy release Fourier transform ion cyclotron resonance spectroscopy. The chloride product ion is observed to be highly translationally excited for the SN2 reaction, indicating a cold internal energy distribution for the products. For the chlorobenzene reaction the products are not generated with large translational energies. The results are compared with a statistical model. Ion-intensity profiles for the CH3Cl reaction deviate significantly from the statistical model whereas the chlorobenzene results are consistent with this model. The kinetic energy release for the CH3C1 reaction is compared with energy-disposal results for the photodissociation and dissociative electron-attachment processes of halomethanes. In all three cases a node in the molecular orbital between the carbon atom and the departing halogen results in a repulsive energy release. Ion-retention curves for the nucleophilic aromatic substitution reaction are consistent with the existence of a long-lived ion-dipole complex on the exit channel for this reaction.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210261118
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  • 5
    Electronic Resource
    Electronic Resource
    Activation of aromatic rings by early transition metal ions in the gas phase. Implications for the metal-catalyzed [2 + 2 + 2] cycloaddition of alkynes and nitriles (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 1616-1622 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of a series of monocyclic and bicyclic arenes with early transition metal ions (Sc+, Y+, Nb+ and Ta+) and their oxides and dioxides were studied in a Fourier transform ion cyclotron resonance mass spectrometer. Ring cleavage of the nitrogen-containing heterocycles results in loss of HCN as the dominant pathway. Thermochemical considerations, secondary reactions and correlations with solution cyclotrimerization reactions indicate that the MC4H4+ product is a metallacyclopentadiene. Based on correspondence between the reactivities of a series of early metals with their valence electron counts, the reactivities of quinoline and isoquinoline and the decomposition behavior of the products, a metallacycloheptatriene intermediate is proposed for the heteroaromatic ring cleavage reaction. These results are compared to metal complexes in solution which catalyze the [2 + 2 + 2] cyclotrimerization of alkynes and nitriles.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210281238
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  • 6
    Electronic Resource
    Electronic Resource
    Dispersion versus absorption (DISPA) method for automatic phasing of fourier transform ion cyclotron resonance mass spectra (1987)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 1 (1987), S. 33-37 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290010209
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of time-domain dynamic range on stored waveform excitation for fourier transform ion cyclotron resonance mass spectrometry (1987)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 1 (1987), S. 39-42 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290010303
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  • 8
    Electronic Resource
    Electronic Resource
    Plasma desorption mass spectrometric analysis of glycosylated ovomucoid third domain from Japanese quail (1988)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 71-73 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290020406
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  • 9
    Electronic Resource
    Electronic Resource
    Dyanmic ion trapping for Fourier-transform ion cyclotron resonance mass spectrometry: Simultaneous positive- and negative-ion detection (1992)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 166-172 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The conventional static electric potential used to trap ions fro fourier-transform ion cyclotron resonance (FTICR) mass spectrometry has been replaced by a low-amplitude [as low as Vac≍0.5 V for N2+] alternating (17.5kHz) electric field applied to the end caps of an ICR ion trap. Ion z-motion is then governed by a Mathieu equation, whose solution leads to a z-stability diagram for which optimal results are obtained at z-stability parameter, qz = 4qλV ac/(mω2)≍0.5, in which m/q is the ion mass-to-charge ratio, Ω is the RF frequency, and λ=2.7737/d2 for a cubic trap of edge length, d. A triangular waveform appears to be more effective than sinusoidal modulation. We demonstrate experimentally three major additional advantages of RF trapping for FTICR mass spectrometry: (a) both positive and negative ions may be trapped and detected simultaneously; (b) Magnetron motion is eliminated, along with the electrostatic radial field-induced ICR frequency shift and sidebands; and (c) mass calibration follows a simpler law (m=a/v, in which a is a constant and v is the measured ICR orbital frequency) than for electrostatic trapping (m=a/v+b/v2, in which a and b are constants). All prior FTICR mass spectrometric capabilities are preserved, except that (as in an RF-only quadrupole ion trap) optimal sensitivity is observed only for 0.4≤qz≤0.7, so that the mass-to-charge ratio range for a single FTICR mass spectrum is limited accordingly.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290060303
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  • 10
    Electronic Resource
    Electronic Resource
    Mass fragmentographic determination of unlabeled and deuterium labeled methadone in human plasma. Possibilities for measurement of steady state pharmacokinetics (1975)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 2 (1975), S. 197-200 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mass fragmentographic method for simultaneous measurement of unlabeled and deuterium labeled methadone in human plasma is described. This specific method has a lower sensitivity of about 16 pmol/ml with a coefficient of variation of less than 4%. The usefulness of the method was evaluated in studies on opiate dependent subjects undergoing methadone maintenance treatment. In one application methadone-d3 was given as a pulse dose during continuous treatment with unlabeled methadone and plasma levels of both species followed by mass fragmentography. The method will be of value in the study of methadone pharmacokinetics in the steady state and in other in vivo situations where multiple drug pools must exist.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200020406
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