CIE A Level Chemistry复习笔记8.1.2 Gas/Liquid Chromatography: Basics

Gas/Liquid Chromatography: Basics

  • Gas-Liquid Chromatography (GLC) is used for analysing:
    • Gases
    • Volatile liquids
    • Solids in their vapour form
  • The stationary phase:
    • This method uses a column for the stationary phase
    • A non-polar, long-chain, non-volatile hydrocarbon with a high boiling point is mounted onto a solid support
    • Small silica particles can be packed into a glass column to offer a large surface area
    • Sample gas particles travel through this phase and are able to separate well due to the large surface area
  • The Mobile phase
    • An inert carrier gas (eg. Helium, Nitrogen) moves the sample molecules through the stationary phase

Retention times

  • Once sample molecules reach the detector, their retention times are recorded
    • This is the time taken for a component to travel through the column
  • The retention times are recorded on a chromatogram where each peak represents a volatile compound in the analysed sample
  • Retention times are then compared with data book values to identify unknown molecules


A gas chromatogram of a volatile sample compound has six peaks. Depending on each molecule’s interaction with the stationary phase, each peak has its own retention time