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  • 1975-1979  (10)
  • 1970-1974  (2)
  • 1935-1939
  • Analytical Chemistry and Spectroscopy  (12)
  • 1
    Electronic Resource
    Electronic Resource
    Determination of phenylbutazone, tolbutamide and metabolites in plasma and urine using chemical ionization mass spectrometry (1977)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 4 (1977), S. 42-47 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantitative analytical procedures for the analysis of phenylbutazone and tolbutamide levels in plasma have been developed which involve the addition of deuterium labeled internal standards to plasma followed by extraction and direct sample insertion into a mass spectrometer operating under chemical ionization conditions. Peak height ratios used to calculate plasma levels were determined by using either selected ion monitoring or repetitive scan data. The scan approach was used in a related procedure for the simultaneous determination of tolbutamide and two metabolites from urine. The accuracy, precision and sensitivity of the direct sample insertion approach to drug level measurement has been determined. Examples are given of data obtained in the course of pharmacokinetic studies in which this analytical approach appears to offer advantages in the analysis of multicomponent mixtures encountered in drug-drug interaction studies.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200040105
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  • 2
    Electronic Resource
    Electronic Resource
    The generation, absorption and anisotropy of thick-target bremsstrahlung and implications for quantitative energy dispersive analysis (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 5 (1976), S. 154-168 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The bremsstrahlung spectrum from a thick specimen bombarded with 20 ke V electrons is studied with emphasis on the shape rather than the absolute intensity in the energy range 1-10 keV. Monte Carlo calculations are described in detail and used to compare the absorption corrections for characteristic and continuous (bremsstrahlung) radiation from a thick specimen and to determine the extent to which anisotropy modifies the intensity distribution of the continuum. The absorption corrections are found to differ by roughly 5% for f(χ) = 0.5 and 10% for f(χ) = 0.2, but it is shown that the ratio of the corrections can be predicted by using the ratio of two Philibert-type formulae. Anisotropy has little influence on the absorption correction but changes in atomic number or geometry may result in the intensity distribution being altered by typically 5-10% across the energy range 1-10keV. Numerical integration gives values for the generated brems-strahlung intensity which are used in constructing an expression to represent the functional form of the background. Although experimental spectra confirm this to be superior to the combination of Kramers' law and a characteristic absorption expression, several sources of error at low energies, including bremsstrahlung from the Be window, are pointed out and improvements suggested. In order to eliminate the principal uncertainty, that of the overall efficiency curve for a Si(Li) detector and pulse-processor, it is recommended that a stored spectrum be used as a ‘background standard’ for explicit background corrections. Errors are then reduced to the 0.1% absolute concentration level, which is suitable for quantitative analysis.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300050310
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The significance of field ionisation kinetics to ion structure: Isomerisation and decompostition of [C4H8]+· radical ionsWe follow our own suggestion14 in referring to the technique through which kinetics of ion decomposition can be determined in the picosecond and nanosecond timeframes as “field ionisation kinetics (FIK).” (1975)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1975), S. 563-578 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of formation of [C3H5]+[M — CH3]+, [C3H4]+·[M — CH4]+· and [C2H4]+·[M — C2H4]+· from but-1-ene, cis- and trans-but-2-ene, 2-methylpropene, cyclobutane and methylcyclopropance following field ionisation have been determined as a function of time 20 (or 30) picoseconds to 1 nanosecond and at two points in the microsecond time-frame. The results are consistent with the supposition that at the shortest accessible times (20 to 30 picoseconds) the structure of the [C4H8]+· molecular ion qualitatively resembles that of its neutral precursor, but suggest that prior to decomposition within nanoseconds the various molecular ions (excepting cyclobutane where the processes are slower) attain a common structure or mixture of structures. Reaction pathways of the presumed known ion structures are delineated from the nature of decompostion at the shortest times.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210100802
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Energetics of the loss of H2 from [C3H7]+ (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 386-388 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The internal energies of [C3H7]+ ions contributing to the metastable peak [C3H7]+ → [C3H5]+ + H2 are higher (by perhaps 〉 100 kJ mol-1) than those of the ion contributing to the threshold current in appearance energy measurements on [C3H5]+. The measured appearance energy may lead to an underestimation of the activation energy, i.e. negative ‘kinetic shift’, due to quantum, mechanical tunnelling. The distribution of energy released in the decomposition can be explained on the basis that much of the reverse activation energy and a statistical proportion of the excess energy is released as translation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210130705
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  • 5
    Electronic Resource
    Electronic Resource
    Ultra long range 19F—19F spin-spin coupling (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 126-127 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The observation of long range (10-14 bond) spin-spin coupling between fluorine nuclei (which are very far apart in space) is used to provide information about electronic interactions in bridged dinuclear aromatic compounds.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060215
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  • 6
    Electronic Resource
    Electronic Resource
    Mass spectral fragmentations of aminoketones in which charge is not localized exclusively on nitrogen (1970)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1970), S. 1307-1315 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The low resolution mass spectra of α-dimethylaminoacetophenone and γ-dimethylaminobutyrophenone are compared to those of δ-methylhexanophenone and dimethyl n-butylamine as well as to those of α-dimethylaminoacetonitrile and γ-dimethylaminobutyronitrile. Analysis indicates that significant fractions of the fragmentations of the aminoketones are directed by the carbonyl. In particular, McLafferty rearrangement of the γ-aminoketone is favored over α-cleavage from nitrogen at ionizing voltages below 15 eV. Although the overall fragmentation patterns are presumably determined both by the distribution of charge and by the relative rates of the fragmentation processes available to the two ionized groups, the intrinsic rates for α-cleavage at ionized nitrogen and at ionized carbonyls appear to be very similar. Kinetic analysis suggests that 26% of the charge resides on the carbonyl in the γ-aminoketone molecular ion. The extent of delocalization of charge in any aminoketone may be partially controlled by the extent of spatial overlap of the two groups. Correlations of mass spectral behavior with photochemical behavior are thus limited because electronic excitation is more localized in the lowest excited states of molecules than charge is in electron-impact produced molecular ions.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210031010
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  • 7
    Electronic Resource
    Electronic Resource
    On the formation of doubly charged ions in field ionization (1975)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1975), S. 1171-1173 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The observation of doubly charged ions in field ionization with blade or wire emitters does not in itself indicate that high excitation energies (≥ 17 eV) are accessible through gas phase ionization with such emitters.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210101218
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetic energy release in unimolecular decompositions of ions. hydrogen rearrangements (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 337-340 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The partition of reverse activation energy in hydrogen rearrangements is considered in terms of atomic motions composing the transition state reaction coordinate. It is shown how this approach predicts that, in general, elimination of H2 from any small ion (as defined in the paper) is likely to be characterized by partition of significant proportions of any reverse activation energy as translational energy of the products. Hydrogen rearrangements in large ions leading to fragments of comparable mass are much less likely to partition reverse activation energy into product translation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210140610
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  • 9
    Electronic Resource
    Electronic Resource
    Correction of metastable peak shapes to allkow for instrumental broadening and the translational energy spread of the parent ion (1976)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 440-442 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Graphs are presented which can be used to correct metastable peak widths for both instrumental broadening and translational energy spread of the parent ion.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210110418
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  • 10
    Electronic Resource
    Electronic Resource
    A standard form for the presntation of field ionization kinetics data (1976)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 835-837 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is suggested that division of the rates of molecular ion decomposition by the measured mass-resolved molecular ion current be adopted as the standard method of normalizing these data obtained through the field ionization kinetics technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210110807
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