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  • 1
    Digitale Medien
    Digitale Medien
    Increased speed of steroid analysis by capillary GC and GC-MS; effects of sample pretreatment and sample introdution (1984)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 7 (1984), S. 414-422 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary columns ; Steroid analysis ; Sample pretreatment ; Sample introduction ; Separation speed ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Quantitative analysis of steroids and their metabolites in urine samples calls for increased speed of sample clean-up, of the derivatization procedure, and of separation. A fast procedure for sample pretreatment, which can be performed within 8 hours, is introduced and evaluated. It is shown that use of fast pretreatment in combination with narrow bore columns, which are compatible with existing instrumentation, can considerably increase, laboratory throughput. The effect of different sample introduction techniques (e.g. splitless, on-column, and moving needle) on column efficiency and resolution is demonstrated and discussed.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240070713
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  • 2
    Digitale Medien
    Digitale Medien
    The effect of column characteristics on the minimum analyte concentration and the minimum detectable amount in capillary gas chromatographyBased on a lecture delivered at the First Latin-American Congress on Chromatography (COLACRO) Rio de Janeiro, Brazil, March 17-19, 1986. (1986)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 752-759 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Capillary gas chromatography ; Detection limits ; Trace analysis ; Narrow bore columns ; Wide bore columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The need for faster and more efficient separations of complex mixtures of organic compounds by gas chromatography has led to the development of small inner diameter open tubular columns. Owing to their decreased plate height, extremely narrow peaks are obtained. When differently sized columns with equal plate numbers are compared, injection of a fixed amount of a solute will give the highest detector signals for the smallest bore columns. When P is defined as the ratio of the column inlet and outlet pressures, it can be seen from theory that under normalized chromatographic conditions the minimum detectable amount (Qº) for a mass flow sensitive detector increases proportionally to the square of the column diameter for P = 1. In the situation of greater interest in the practice of open tubular gas chromatography where P is large, a linear relationship is derived between Qº and the column diameter.It is a widespread misunderstanding, however, that narrow bore capillary columns should be used for this reason in trace analysis. If a fixed relative contribution of the injection band width to the overall peak variance is allowed, a decreased plate height drastically restricts the maximum sample volume to be injected. It is shown that the minimum analyte concentration in the injected sample (Cº) is inversely proportional to the column inner diameter when a mass flow sensitive detector is used. For actual concentrations less than Cº, sample preconcentration is required. The effect of peak resolution and selectivity of the stationary phase in relation to Cº and Qº will be discussed as well. The validity of the given theory is experimentally investigated. Minimum analyte concentrations and minimum detectable amounts are compared using columns with different inner diameter.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240091208
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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