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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of polycyclic aromatic compounds by supercritical fluid charomatography/mass spectrometry using atmospheric-pressure chemical ionizationNRCC #31956. (1991)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 5 (1991), S. 149-155 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The development of microbore packet-column supercritical fluid chromatography/atmospheric pressure chemical ionization mass spectrometry (SFC/APCI-MS) for the analysis of polycyclic aromatic compounds (PAC) is described. The SFC system was coupled to the mass spectrometer using an improved interface designed to accommodate commercially available fused silica restrictors. The atmospheric pressure chemical ionization characteristics of PAC are discussed and the use of chemical ionization reagents to modify the type of spectra obtained is described. With selected-ion monitoring techniques the interface provided detection limits in the low picogram range for individual PAC standards. Using a photoionization detector for the off-line optimization of chromatographic conditions, SFC/APCI-MS was applied to the analysis of complex mixtures of PAC in coal tar and tar sand oil extracts. Tandem mass spectrometry was used to provide structural information.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290050403
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  • 2
    Electronic Resource
    Electronic Resource
    Charge-transfer ionspray liquid chromatography/mass spectrometry analyses of fullerenes and related compounds from flame-generated materialsNRCC No. 34830. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 229-234 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A flame-generated, fullerene-rich material (J. B. Howard et al., Nature 352, 139 (1991)) has been characterized by liquid chromatography coupled on-line to ionspray mass spectrometry. Charge-transfer complexation, using a post-column addition of either an electron donor or acceptor, was utilized as a pre-ionization technique. Analyses in the positive-ion mode showed that the thermally metastable constituents of the flame-generated material, tentatively identified previously (J. F. Anacleto et al., Rapid Commun. Mass Spectrom. 6, 214 (1992)) as fullerene isomers on the basis of atmospheric pressure chemical ionization muss spectrometry, yielded mass spectra consistent with their identification as fullerene adducts with highly uiuaturated moieties CnH2n-4 with n = 5, 6, and 7. The molecular radical cations of these adduct species were susceptible to facile fragmentation yielding the molecular ions of the corresponding fullerenes. The negative-ion mode experiments failed to provide any information regarding the identity of these metastable constituents.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290070313
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  • 3
    Electronic Resource
    Electronic Resource
    Calibration of ion spray mass spectra using cluster ionsNRCC No. 33771. (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 660-666 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass calibration for ion spray mass spectrometry can be achieved by using cluster ions formed by flow injection of solutions of alkali metal salts in aqueous acetonitrile into the liquid flowing to the ion spray needle. Source contamination is thereby reduced to a minimum. For quadrupole mass analyzers, sodium iodide provides an ideal compromise between undesirable spectral complexity and spacings between calibrant mass peaks sufficiently close that interpolation errors are negligible. When much closer spacings are required, protonated water clusters provide an excellent calibration up to about m/z 1000. If higher mass ranges are required with a large number of calibrant peaks, a solution of mixed alkali metal iodides does provide the expected spectra but intensities are poor at higher m/z values. For liquid chromatography with on-line mass spectrometry (LC/MS) the mass calibration may be checked without changing the mobile phase by post-column flow injection of a cesium carbonate solution, since the carbonate anion is wholly displaced by the anion of the mobile phase acid modifier, resulting in no mixed clusters. The metal salt calibrants have the additional advantage of being useful over a wide range of tuning parameters in the atmospheric pressure ionization source, covering those appropriate to both relative molecular mass determinations of large proteins and to LC/MS of small analyte species.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210270603
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