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Spectroscopy and Chromatography

Gas–liquid chromatography

  • 3 things to know
  • Unit A2 2

Overview

Two phases in gas–liquid chromatography, two gases used as the carrier and retention time.

What you need to know

Answer each one before you reveal it.

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Key term

What are the two phases in gas–liquid chromatography?

Key term

Name two gases used as the carrier in gas–liquid chromatography

Key term

Why is the column in gas–liquid chromatography held in an oven?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What are the two phases in gas–liquid chromatography?

    Model answer

    A high boiling liquid held on an inert solid support inside the column is the stationary phase, and an unreactive carrier gas is the mobile phase.

  2. 2

    Name two gases used as the carrier.

    Model answer

    Nitrogen and helium.

  3. 3

    Why must the carrier gas be unreactive?

    Model answer

    It must move the sample through the column without reacting with it or with the stationary phase.

  4. 4

    Why is the column held in an oven?

    Model answer

    The components must stay in the vapour phase to travel with the carrier gas, and a controlled temperature makes the retention times reproducible.

  5. 5

    What determines how long a component takes to pass through?

    Model answer

    How volatile it is and how strongly it dissolves in the liquid stationary phase; a component that dissolves readily is held back.

  6. 6

    What is the retention time?

    Model answer

    The time between injection and the appearance of that component at the detector.

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