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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 1055-1058 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A System to automate the analysis of routine mass spectrometry samples, using either a thermospray or particle-beam interface, has been developed. This has allowed unattended operation and has freed expert mass spectrometrists to address ‘real’ problems. The system also acts as a filter to the problem-solving service.
    Additional Material: 2 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 1059-1061 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The non-ionic surfactant Triton X-100, 1-(1,1,3,3,-tetramethylbutyl)-4-[poly(1,2-ethanediol)]benzene, has been evaluted as a reference material for positive-ion high-resolution ammonia chemical ionization (CI) mass spectrometry and as a tuning and calibration material for positive-ion thermospray mass spectrometry (TSP). When ammonia is used as the CI reagent gas, Triton-X-100 produces evenly spaced ions that 44 u apart. Triton X-100 cab be volatilized from a solids prove and is routinely used as the reference material for high-resolution measurements. A reference table has been constructed from the theoretical values for the different masses. Triton X-100-Reduced and Triton X-405-Reduced were also evaluated as additional reference com-pounds. As a calibration and tuning compound for TSP, Triton X-100 affords an envelope of ions centred around m/z 600-700 with ions observed above m/z 1000. Triton X-100-Reduced affords a similar envelope although the ions observed are 6 u higher in mass.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 492-495 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A mixture of four squalestatins was separated and characterized by gradient-packed capillary liquid chroma-tography combined with dynamic liquid secondary-ion mass spectrometry (LSIMS). Thioglycerol/glycerol matrix was added post-column. Negative-ion LSIMS was found to afford spectra typified by strong molecular ions with structurally informative fragments. The new method showed improvements in sensitivity and specificity for this class of compound when compared to existing thermospray methods.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 953-956 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A mixture of four squalestatins was separated anil characterized by gradient packed capillary liquid chromatography combined with electrospray collision-induced dissociation mass spectrometry (ESI/CID/MS). Negative-ion ESI was found to afford spectra typified by strong pseudo-molecular ions but providing little structural information. Structural information was obtained using an ion-focusing RF-only octapole lens to provide conditions for CID. The new method showed improvements in sensitivity when compared to existing thermospray and dynamic liquid secondary-ion mass spectrometry methods.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 261-263 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A liquid chromatography/mass spectrometry methodology is described that enables the simultaneous estimation of the individual protein-binding affinities of a mixture of compounds. This approach has proved to be robust and enables a series of molecules to be ranked according to their protein-binding affinities within 20 minutes.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 1283-1287 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Capillary electrochromatography (CEC) was coupled with electrospray (ESI) mass spectrometry and evaluated as an on-line high resolution technique for the separation and characterization of some typical pharmaceutical compound mixtures. Dispersion effects were observed and are discussed in the context of an optimized CEC/MS interface.
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1983), S. 494-496 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 477-482 
    ISSN: 0935-6304
    Keywords: Shape selectivity ; Polycyclic aromatic hydrocarbons ; Isomers ; Coupled columns ; Coal tar ; SRM 1597 ; SRM 869 ; SRM 1647c ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The retention behavior of polycyclic aromatic hydrocarbons (PAHs) in packed-column supercritical fluid chromatography (SFC) is studied for monomeric and polymeric C18 columns. Molecular shape discrimination (shape selectivity) is assessed through the use of Standard Reference Materials (SRMs), adn changes in selectivity are studied as a function of temperature, pressure, and mobile phase composition. Examples of separations of complex PAH isomer mixtures are presented, and guidelines are provided for modification and optimization of shape selectivity in SFC.
    Additional Material: 6 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 6 (1994), S. 115-125 
    ISSN: 1040-7685
    Keywords: gas chromatography ; stationary phases ; liquid crystal polysiloxane ; C18 polysiloxane ; shape selectivity ; polycyclic aromatic hydrocarbons ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Column selectivity is examined for a series of smectic liquid crystalline columns and is compared with methyl and C18 polysiloxane columns for the separation of polycyclic aromatic hydrocarbon (PAH) isomers. A set of extended and condensed solute probes is described that provides a sensitive indication of variations in column shape selectivity. Examples of shape selectivity differences are presented for smectic liquid crystalline columns and 5% phenyl polysiloxane columns using various PAH isomer sets. Variations in selectivity have been observed among different smectic liquid crystalline columns, and this problem appears more significant than for methyl polysiloxane columns. The selectivity ration for tetraphenylmethane and p-terphenyl provides a sensitive indication of column shape selectivity, with a change in elution order occurring between ordered (smectic liquid crystalline) columns and non-ordered (methyl polysiloxane) columns. Shape selectivity differences indicated by this test mixture are apparent for more complex PAH isomer mixtures. Despite stationary phase selectivity variability, smectic liquid crystalline columns offer considerable potential for solving difficult separation problems involving structured solutes.
    Additional Material: 10 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 9 (1980), S. 134-136 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rates of deuterium exchange of the 8-CH groups of 5′-rGMP and cGMP in D2O solutions (KH) are compared with rates of protium exchange of the 8-CD groups of the same compounds in H2O solutions (KD). The ratio of the two rate constants (kH/kD) defines an isotope effect which is a combination of primary kinetic and solvent isotope effects, the former predominating. The net isotope effect was measured by Raman spectrophotometry over the temperature range 30-80°C. The Arrhenius activation energies (Ea) and pre-exponential frequency factors (A) were also determined. The average values of kH/kD are 1.82 ± 0.15 for 5′-rGMP and 1.43 ± 0.06 for cGMP. The relatively small kinetic isotope effects are indicative typically of an unsymmetrical transition state. The ratio EaH/EaD is unity in both compounds, indicating an early or reactant-like transition state. The present data are consistent with, and extend the range of, the Bell-Goodall curve relating log (kH/kD) to ΔpK of the two acid-base systems involved in the proton transfer during the rate-determining step.
    Additional Material: 1 Ill.
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