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The GC system

  • Page ID
    61144
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    Scheme of universal GC

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    A GC system generally consists of:

    • Gas supply and flow/pressure control
      The mobile phase (the carrier gas in GC) is supplied by either gas cylinders or by generators designed for the purpose. This supply must be controlled precisely and accurately by pressure or flow controllers.
    • Injector
      Samples to be analysed are introduced onto the column by means of the injection system.
    • Column
      The central and most important component of a gas chromatograph is the column. The column is the heart of the system where the separation occurs and it is true to say that the final separation is only as good as the column. Poor separation cannot be compensated for by expensive instrumentation!
    • Oven
      The temperature in the column must be controlled accurately, either by maintaining it at a known fixed level (isothermal operation) or by increasing the temperature during the separation in a specific manner (programmed temperature operation).
    • Detector
      Following elution from the column, the individual sample components are detected as they flow through the detector. The output from the detector is supplied to an amplifier, followed by a data system or recorder. The analog monitoring of the detector output versus time is called a chromatogram. It consists of a series of peaks corresponding to the components.
    • Data system
      Qualitative identification is based on the time that the peaks elute from the column and is subsequently detected. Quantitative analysis is based on peak size or peak area.

    The GC system is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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