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  • Analytical Chemistry and Spectroscopy  (36)
  • Mass spectrometry  (2)
  • 1
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The determination of serum cortisol by thermospray liquid chromatography/mass spectrometry (LC/MS) has been assessed. The method incorporates stable isotope dilution and innumoadsorption extraction. [M + H]+ ions are monitored during LC/MS. The within-assay reproducibility is satisfactory (coefficient of variation 7% at a concentration of 190 ng ml-1), though inferior to that achieved with the (more lengthy) procedure of gas chromatography/mass spectrometry (GC/MS). Satisfactory agreement between LC/MS (y) and GC/MS (x) data was observed (y = 0.934x + 12.4 ng ml-1; r = 0.968; n = 14). It is concluded that the generation of precise reference data for the assessment of routine cortisol assays is at present better achieved by GC/MS. LC/MS, however, provides satisfactory quantitative data via a more simple and rapid method.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 617-621 
    ISSN: 0935-6304
    Schlagwort(e): Capillary electrophoresis ; Mass spectrometry ; Electrospray ionization ; Fourier transform ion cyclotron ; Resonance ; Biomolecule analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We describe the current state of the on-line combination of capillary electrophoresis (CE) electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS), and discuss aspects of the FTICR technique relevant to its use as a detection scheme for on-line separations. Aspects including sensitivity, mass resolution, duty cycle, and tandem mass spectrometric capabilities are discussed in the context of online separations with examples from the authors' laboratory.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ammonia desorption chemical ionization (NH3-DCI) mass spectra of peracetylated gentiobiose (1) and two isotopically labelled gentiobioses (2 and 3) were examined. Compound 2 is labelled with trideuteroacetyl groups in the non-reducing moiety and 3 with trideuteroacetyl groups in the reducing moiety. It is shown that the [M + NH4 - 42]+ ion is not formed direct from [M + NH4]+ by loss of ketene but appears to be formed by way of a nucleophilic acyl substitution reaction resulting in a neutral species which complexes with NH4+. The disaccharides undergo cleavage at either side of the glycosidic oxygen joining the two sugar residues, a process which is accompanied by addition of H or CH3CO to afford neutral species which complex with NH4+. The structures of the ions resulting from H transfer have been inferred by comparison of their mass-analysed ion kinetic energy (MIKE) spectra with MIKE spectra of the [M + NH4]+ ions of compounds of established structure. A ring fragmentation reaction of 1, 2 and 3 is reported.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 207-210 
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 644-650 
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A new approach, bio-affinity characterization mass spectrometry (BACMS), aimed at providing a more rapid, sensitive and potentially more flexible alternative to techniques presently employed for the characterization of noncovalent interactions in mixtures, such as would be encountered in combinatorial chemistry, is presented. BACMS avoids some of the difficulties and potential artifacts associated with affinity chromatography since the noncovalent associations occur in solution; thus, BACMS avoids the requirement of solid support media and the development of non-interfering linker species. This paper describes the conceptual basis for the methodology and its potential use in applications which include the screening of high affinity ligands in support of new drug development. BACMS exploits new Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry technologies which, when coupled to electrospray ionization (ESI), allow the investigation of specific noncovalent complexes formed in solution. BACMS utilizes the well-known attributes of FTICR, such as the high resolution mass analysis and (MS)n (n ≥ 2) capabilities; however, it is even more directly a result of recently developed techniques involving quadrupolar excitation, such as selected-ion accumulation. These tools are demonstrated and the results illustrate the extraordinary sensitivity achievable (solution concentrations of 1 × 10-9 M without the use of separations prior to ESI). Thus, the new capabilities demonstrated here, in conjunction with ESI, will be useful for the investigation of very low relative concentration noncovalent association directly from solution, and promote a faster alternative for combinatorial mixture screening and analysis.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 312-316 
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The stoichiometry of a noncovalent, hydrogen-bonded supramolecular complex, hub(M)3·RCA3, was characterized using electrospray ionization from chloroform. The intact (1:3) complex was observed in the negative-ion mode as a Cl--bound species using Ph4PCl as the source of the charge donor. Collisionally and thermally induced dissociation of the (1:3) complex resulted in the simultaneous loss of all the three RCA units, indicating a cooperative binding of RCA units in the (1:3) complex. These results suggest that the attachment of small, organic-soluble ions may be a useful technique for mass spectrometric characterization of neutral supramolecular complexes that are stable or soluble only in non-polar organic solvents.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electrospray ionization collisionally activated dissociation (CAD) mass spectra of multiply charged human hemoglobin β-chain variant proteins (146 amino acid residues, 15.9 kDa), generated in the atmospheric pressure/vacuum interface and in the collision quadrupole of a triple-quadrupole mass spectrometer, are shown and compared. Several series of structurally informative singly and multiply charged b- and y-mode product ions are observed, with cleavage of the Thr 50-Pro 51 CO—NH bond to produce the complementary y96 and b50 sequence ions as the most favored fragmentation pathway. The eight different β-globin variants studied differ by a single amino acid substitution and can be differentiated from the observed m/z shifts of the assigned product ions. The overall fragmentation patterns for the variant polypeptides are very similar, with the exception of the Willamette form, in which Arg is substituted for Pro- 51, and multiply charged y96 product ions are not observed. Circular dichroism spectra of normal βA and βWillamette show very little difference under a variety of solvent conditions, indicating that fragmentation differences in their respective CAD mass spectra are substantially governed by primary rather than secondary structure.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1993), S. 493-501 
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1993), S. 181-183 
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In 10 mM sodium phosphate, pH 7.6, containing 0.1 mM ethylenediaminetetraacetic acid, ions corresponding to the non-covalent, four-stranded oligonucleotide, d(CGCG4GCG)4, were detected by negative ion electrospray ionization (ESI) mass spectrometry at a low nozzle-skimmer (ΔNS) bias (-150 V), but not at a higher ΔNS bias (〉 -250 V). In contrast, when the sample was desalted and analyzed by ESI mass spectrometry at a low ΔNS bias only ions for the single-stranded d(CGCG4GCG) species were observed. These data agree with spectroscopic evidence which showed that oligonucleotides with the sequence motif 5′d(CGCGnGCG)3′, where n = 2-5, formed stable four-stranded complexes in the presence of monatomic cations, like K+, Ca2+, Na+ and Li+, but not in their absence.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The occurrence of small shifts in the cyclotron frequency during the acquisition of very long transients (in excess of 80 s) has been observed to be a limiting factor for ultrahigh-resolution mass measurements of protein ions performed with electrospray-ionization Fourier-transform ion-cyclotron-resonance mass spectrometry. Resolution measurements were restricted to values less than 106 because of the frequency shifts. Measurements of the frequency shifts, performed by sequentially transforming small segments of the transient, allowed the shift to be characterized and fitted to a 4th-order equation. The sampling rate of the acquired transient was then modulated (at a rate equal to the reciprocal of the rate for the frequency shift) to allow ultrahigh resolution, greater than 2 × 106, and improved mass measurement and precision to be achieved for a small protein.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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