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  • Gas chromatography  (5)
  • Condensed Matter: Electronic Properties, etc.
  • Diptera
  • Nederland
  • Surface physics, nanoscale physics, low-dimensional systems
  • 2015-2019
  • 1995-1999  (5)
  • 1995  (5)
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  • 2015-2019
  • 1995-1999  (5)
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  • 1
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Atomic emission detection ; Aqueous samples ; Solid-phase extraction ; Organophosphorus pesticides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An on-line, solid-phase extraction gas chromatography atomic-emission detection (SPE-GC-AED) system has been set up using an on-column interface to transfer 100 μl of desorbing solvent to the GC part of the system. Analytical characteristics such as recovery, precision and linearity of calibration plots were comparable with those of the off-line combination of SPE-GC-AED using organophosphorus pesticides as test compounds. The fully on-line set-up causes a marked improvement in detection because of the quantitative transfer of the analytes from the SPE module to the GC: detection limits are as low as 5–20 ng l−1 for the analysis of 10 ml raw and spiked surface water samples using the phosphorus channel. Detection levels can be further enhanced by processing up to 100 ml samples. The integrated analytical system is robust. The potential of the on-line set up has been demonstrated for the analysis of surface water and waste water.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Phosphine ; Flame photometric detection ; Anaerobic bacteria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A gas chromatographic method is presented which distinguishes phosphine from hydrogen sulfide and other possible headspace gases of anaerobic microbial cultures. In anaerobic cultures spiked with phosphine, this gas is recovered in the liquid and gaseous phase down to 10 pg per ml of gas or liquid. No biogenically produced phosphine was found. Phosphine in amounts as small as 30 ng per 1 can be stored for several days in glass bottles covered with rubber septa, filled with nitrogen, in the presence or absence of water or of an anaerobic bacterial culture. Due to the selectivity of the detector and the retention characteristics of the porous layer open tubular polymer column alkanes, alkenes and organosulfur compounds routinely found in anaerobic bacterial headspaces do not interfere with the analytical quantification of phosphine.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Column liquid chromatography ; On-line coupling ; Ion-exchange membrane ; Ion-pair reagent
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary In order to enable the coupling of reversed-phase liquid chromatography (RPLC) with capillary gas chromatography (GC), the performance of an anion-exchange micromembrane device has been studied to remove the ion-pair reagent methanesulphonic acid from an acetonitrile/water LC eluent. The regenerant in the membrane was tetrabutylammonium hydroxide dissolved in acetonitrile/water, which effects an anion-exchange of methanesulphonate ions for regenerant hydroxide ions. The efficiency of the exchange process was found to be 99.9%. This enabled the direct introduction of the LC eluent, free of ions and with the proper acetonitrile/water ratio, into the GC. The applicability of the on-line LC-micromembrane-GC system has been illustrated for the potential drug eltoprazine, which is quantitatively recovered with a coefficient of variation for standard solutions of 3% at the 150 μg/ml analyte level.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; ASPEC ; Trazodone in plasma ; Method automation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An automated sample preparation module, (the automated sample preparation with extraction columns, ASPEC), was interfaced with a capillary gas chromatograph (GC) by means of an on-column interface. The system was optimised for the determination of the antidepressant trazodone in plasma. The clean-up of untreated plasma was carried out with disposable C18 cartridges, using several washing steps. The analyte was desorbed with methanol, the extract was diluted on-line with buffer and preconcentrated on a PLRP-S trapping column. The trapping column was dried by purging with nitrogen gas. Desorption (phase switching) of the trapping column was carried out with ethyl acetate which was introduced into a retention gap using partially concurrent solvent evaporation conditions. Trazodone was determined by GC with flame ionisation detection (FID). With a 1 ml sample, this resulted in a detection limit for trazodone in plasma of 3 ng/ml. The system showed good linearity and repeatability in the range 0.01–1 μg/ml, thus covering the range of pharmacokinetic/dynamic-to-therapeutic concentrations of trazodone in plasma. Preliminary results for benzodiazepines are promising. They indicate that the use of a selective detector such as the nitrogen/phosphorus detector, is to be recommended.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 19-27 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Large volume injection ; PTV injectors ; PTV splitless injection ; PTV solvent split injection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Temperature programmable injectors with liner diameters ranging from 1 to 3.5 mm are evaluated and compared for solvent split injection of large volumes in capillary gas chromatography. The liner dimensions determine whether a large sample volume can be introduced rapidly or has to be introduced in a speed controlled manner. The effect of the injection technique used on the recovery of n-alkanes is evaluated. Furthermore the influence of the liner diameter on the occurrence of thermal degradation during splitless transfer to the analytical column is studied. Guidelines are given for the selection of the PTV liner internal diameter best suited for specific applications.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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