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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 207-210 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 4 (1992), S. 191-198 
    ISSN: 1040-7685
    Keywords: benzo[a]pyrene-adducted DNA ; capillary zone electrophoresis ; micellar electrokinetic capillary chromatography ; microcolumn HPLC ; electrospray ionization mass spectrometry ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analysis of DNA adducts as indicators of human exposure to environmental levels of carcinogenic compounds represents an extreme challenge for trace analyses to chemists. At environmental exposure levels of benzo[a]pyrene, one can expect less than one adduct per 107 base pairs, or roughly 30 femtomoles of adduct per mg DNA. Microcolumn separation techniques are ideally suited for the trace analysis of DNA adducts due to the high separation efficiency, enhanced mass flow sensitivity, and ease of interfacing with highly specific and sensitive mass spectrometric detectors. This study describes the analysis of benzo[a]pyrene-adducted deoxyguanosine-5′-monophosphate with micellar electrokinetic capillary chromatographic separation followed by fluorescence detection. Alternatively, adducts can be cleaved from the DNA by treatment with acid, resulting in the formation of highly fluorescent benzo[a]pyrene tetrahydrotetrols. Analysis of the tetrahydrotetrols by either capillary zone electrophoresis or microcolumn HPLC with fluorescence detection is described. Detection limits for the benzo[a]pyrene tetrahydrotetrols with either of the aforementioned separation techniques were approximately 3 femtomoles.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 1 (1989), S. 223-229 
    ISSN: 1040-7685
    Keywords: CZE-MS ; electrospray ionization ; peptides ; proteins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary zone electrophoresis (CZE) coupled with an on-line mass spectrometric (MS) detection system by an atmospheric pressure electrospray ionization (ESI) interface has been used successfully for Separations of peptide and protein mixtures. For CZE-MS, ESI produces multiply charged molecular ions and thus allows mas spectrometers with a limited mass-to-charge range to analyze proteins having molecular weights greater than 100,000. Various pH buffer systems have been investigated, including buffer systems in which pH 〉 pI (isoelectric point of analytes) and pH « pI are designed to reduce protein adsorption onto silica capillary surfaces and thus improve separation efficiencies. More than 125,000 theoretical plates have been obtained from a CZE-MS separation of less than 1 pmol per component of leucine enkephalin and horse heart myoglobin. CZE-MS of other large peptides and proteins are demonstrated.
    Additional Material: 8 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 5 (1993), S. 57-62 
    ISSN: 1040-7685
    Keywords: capillary electrophoresis ; electrospray ionization ; mass spectrometry ; reduced field strength ; peptides ; proteins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A combined capillary electrophoresis/mass spectrometry (CE/MS) method is described that provides an increase in the efficiency of analysis by decreasing the analyte elution rate into an electrospray ionization (ESI) interface. The method is readily implemented by instituting a step change in the CE electric field strength for desired periods of time during a separation. As a result, the m/z range or the number of times an m/z range can be scanned while a solute elutes is increased by a factor proportional to the decrease in CE electric field strength. In addition, the method is shown not to cause any significant loss in separation quality as demonstrated for mixtures of proteins and peptides, while providing an effective gain in sensitivity. This allows an enhancement in the quality of mass spectra recorded while scanning wide m/z ranges. Mass spectra for a set of standard proteins were obtained for injections of 60 femtomole/protein, while analysis of an albumin tryptic digest was obtained for injections corresponding to 40 femtomoles of protein.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 5 (1991), S. 101-105 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Electrospray-ionization (ESI) mss spectrometry is used to monitor higher order structural changes of polypeptide induced by alteration of the pH or organic solvent composition in the protein solution environment. A bimodal charge-state disribution is observed in the ESI mass spectrometry of ubiquitin (relative molecualr mass 8565) in solution containing small amounts (〈20%) of organic solvents. The distribution of peaks at high m/z (low-charge state) is found to represent the protein in its native, globular state; the higher-charge-state distribution is characteristic for a more extended conformation. Addition of methanol denaturant in excess of 40% v/v is needed to eliminate the low-charge-state distribution completely. Lesser amounts of acetonitrile, acetone, or isopropanol (∼20%) are reqiored to denature the ubiquitin protein. Other proteins showing conformational efects in their ESI mass spectra are also illustrated. While the ESI spectra are related to solution phase structure, ESI-tandem mass spectrometry of multiply charged molecular ions of different conformation is suggested as a probe of gas-phase protein three-dimensional structure.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 160-164 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Electrospray ionization generates multiply charged peptide molecular ions which are efficiently dissociated by collision with a neutral gas to provide sequence-specific daughter ions. The scope for application of this phenomenon is illustrated by the nearly complete sequencing of melittin (relative molecular mass (Mr) 2846.5) employing a tandem quadrupole mass spectrometer having a mass limit of m/z 1400.
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 159-165 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The relationship between gas-phase protein structure and ion/molecule reactivity is explored in comparisons between native and disulfide-reduced aprotinin, lysozyme, and albumin. Reactions are performed in the reactions with equal concentrations of diethylamine, multiply protonated molecules generated by electrospray ionization (ESI) of ‘native’ proteins shifted to lower charge states than did multiply protonated molecules from ESI of the disulfide-reduced counterparts, suggesting that the disulfide-reduced protein ions are less reactive than native protein ions of the same charge state. Differences in reactivity may arise from protonation of different amino acid residues and/or differences in the proximites of charge sites in two molecules. These results suggest that the reactivity of multiply charged proteins can be significantly affected by their gas-phase structure.
    Additional Material: 5 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 5 (1991), S. 582-585 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The thermally induced dissociation (TID) of inos at near atmospheric pressure, followed by their mass spectraometric analysis, is demonstrated. The TID occurs in a heated metal capillary interface, and should be broadly applicable to any system capable of producing ions at high pressure. The heated capillary provides a reaction vessel, potentially very useful for kinetic and mechanistic studies of ions. The technique has been applied to the fragmentation of large multiply charged ions from an electrospray ionization source. Preliminary results show that stability for multiply protonated petide or protein molecules in inversely related to its charge.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Mass Spectrometry Reviews 6 (1987), S. 445-496 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 30 Ill.
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  • 10
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 38 Ill.
    Type of Medium: Electronic Resource
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