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  • Chemistry  (20)
  • Supercritical fluid chromatography  (4)
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  • 1
    ISSN: 1612-1112
    Schlagwort(e): Supercritical fluid chromatography ; Column liquid chromatography ; Polycyclic aromatic hydrocarbons ; Environmental samples
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The separation in 6 minutes of the sixteen US Environmental Protection Agency (EPA) polycyclic aromatic hydrocarbons (PAHs) on a single packed column by supercritical fluid chromatography (SFC) is described and compared to that obtained using liquid chromatography with the same column. Several environmental samples containing polycyclic aromatic hydrocarbons obtained from various sources including soil, water, petrochemicals and coal have been analysed by SFC under optimised conditions. Packed column SFC is shown to be an efficient and promising method for the rapid monitoring of environmental polycyclic aromatic hydrocarbons.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 41 (1995), S. 161-166 
    ISSN: 1612-1112
    Schlagwort(e): Supercritical fluid chromatography ; Molecular mechanics ; Chiral stationary phase ; Matrix interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A model is devised using molecular mechanics to simulate chromatographic separations of enantiomers. Theoretical results derived from this model are compared with experimental findings obtained using supercritical fluid chromatography. The model is then developed to incorporate the effects of binding the stationary phase to a matrix. Computed results show that addition of the matrix into the model has significant effects on the ability of the stationary phase to separate racemic mixtures.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 378-384 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography, GC ; Fused silica capillary columns ; Deactivation ; Phenylhydrosiloxanes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In this work, an investigation of new organosilicon hydride reagents with phenyl functional groups for deactivation and surface modification of fused silica capillary columns is described. Different reagents were tested for their ability to deactivate the fused silica surface, and actual critical surface tension measurements were made using the capillary rise method. The deactivation procedure required lower optimum temperatures than conventional methods. Deactivated capillaries and coated capillary columns were prepared and tested for reproducibility, efficiency, and surface inertness towards basic and acidic compounds at the low nanogram level.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 39-43 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography, GC ; Fused silica capillary columns ; Parallel triple detection ; Diesel fuels ; Polyaromatic hydrocarbons ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Diesel fuels from different parts of the UK have been analyzed for polycyclic aromatic hydrocarbons (PAH), nitrogen-containing PAH, and sulfur-containing PAH using capillary column GC with simultaneous parallel triple detection. The concentrations of polyaromatic compounds (PAC) were high and showed considerable variability amongst the fuels. The PAH are mainly naphthalene, fluorene, and phenanthrene and their alkylated homologs; the PANH are mainly carbazole and its methyl derivatives; the PASH are mainly dibenzothiophene and its methyl derivatives.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 741-747 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Fused silica capillary columns ; Deactivation ; Cyanopropylhydrosiloxanes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method is described for surface deactivation and modification of fused silica capillary columns with a cyanopropyl-containing reagent. The deactivation procedure involved a dehydrocondensation reaction between a bis(cyanopropyl)methylhydropolysiloxane reagent and surface silanol groups at an optimum temperature of only 250°C. Actual critical surface tension measurements were made using the capillary rise method. Excellent deactivation for acidic and basic compounds at the low ng level, and wettability for nonpolar and polar polysiloxane stationary phases were obtained. A procedure was developed to remove acidic impurities that are present in polar stationary phases.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 506-514 
    ISSN: 0935-6304
    Schlagwort(e): Supercritical fluid chromatography, SFC ; Deactivation ; Gas chromatography, GC ; Small diameter capillary columns ; Organosilicon hydrides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Small diameter fused silica capillary columns (50-75 μm i.d.) were deactivated at relatively low temperatures (250-300°C) with a mixture of polymethylhydrosiloxanes and several lowmolecular-weight organosilicon hydrides. Reproducible surface deactivations of highest quality were achieved with the polymethylhydrosiloxane (PMHS) reagent. Deactivations performed with PMHS via dynamic coating with neat or diluted reagent were evaluated by gas chromatography. Deactivations achieved with organosiloxane mono-, tri-, and tetrahydrides were also evaluated and compared. Low-molecular-weight organosilicon hydride deactivations were less time consuming and required lower head pressures for filling and coating columns with the reagent. Critical surface tensions of capillary surfaces modified with PMHS and the low-molecular-weight organosilicon hydrides gave support to the dehydrocondensation reaction between silica surface silanols and silyhydride bonds of the reagents. Slopes from Zisman plots indicated that coverage of the surface ranged from highest for the polymer (PMHS) to lowest for the monomers (TMS and PMDS). Efficiency measurements showed the influence that surface modification had on the uniformity and stability of the coated capillary columns. Well-deactivated capillary columns permitted the chromatography of polar solutes using supercritical carbon dioxide as mobile phase.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 113-118 
    ISSN: 0935-6304
    Schlagwort(e): Static coating ; Biphenyl polysiloxane ; Capillary columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Static coating of phenyl and biphenyl polysiloxane stationary phases on 50 μm i.d. open tubular capillaries was studied. The influence of coating solvents and coating temperatures on the viscosities and surface tensions of the polymer stationary phases and their coating solutions was determined. A measure of the Rayleigh instability paralled the observed coating efficiencies.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 289-291 
    ISSN: 0935-6304
    Schlagwort(e): Supercritical fluid chromatography, SFC ; Capillary columns ; Restrictor ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    ISSN: 0935-6304
    Schlagwort(e): Supercritical fluid extraction, SFE ; Supercritical fluid chromatography, SFC ; Fourier transform infrared microspectrometry, FTIR ; Narrow-bore capillary column ; Polycyclic aromatic compounds, PAC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The combination of supercritical fluid extraction, high resolution capillary supercritical fluid chromatography, and Fourier transform infrared microspectrometry is described for the separation and identification of polycyclic aromatic hydrocarbons in a coal tar pitch. The variable solvating power of the supercritical fluid was utilized to selectively fractionate the sample. The fluid extract was decompressed through a frit restrictor into the sample cavity of a cooled microvalve injector, where the analytes were deposited and concentrated for subsequent chromatographic analysis. Several of the analytes separated in the chromatograph were collected on a potassium bromide disc at a solvent elimination inter-face for subsequent infrared analysis involving the use of an infra-red microscope accessory. The spectra obtained show the power of this detection technique for distinguishing between isomers.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 792-799 
    ISSN: 0935-6304
    Schlagwort(e): Lignite tar ; Hydrocarbons ; Argentation chromatography ; On-line liquid chromatography/gas chromatography (LC/GC) ; Gas chromatography/mass spectrometry (GC/MS) ; Capillary supercritical fluid chromatography (SFC) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This work describes the analysis of a pyrolysis product of a lignite sample obtained from the Turkish Goynuk reserve. The aliphatic, aromatic and polar compounds present in the tar are separated and identified by various chromatographic techniques: Capillary gas chromatography/mass spectrometry (GC/MS), on-line high performance microbore liquid chromatography/capillary gas chromatography (LC/GC) and capillary supercritical fluid chromatography (SFC). The suitability of each technique for this particular application is discussed, and semi-quantitative results are presented for the major components detected.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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