Skip to main content
Chemistry LibreTexts

Gas Chromatography Lecture

  • Page ID
    283889
  • Announcements

    • Complete your course evaluation!
    • Monday May 14th is a review session
    • Wednesday May 16th is the last exam (normal class time and place)

    Previously…

    • We looked at the details of how analytes (solutes) generally behave during chromatography
      • Retention time and order
      • Resolution
      • Band broadening
      • The effects of different experimental conditions

    Today…

    Gas chromatography (GC)!

    • Mini-lecture followed by problem solving

    SLO1: Describe the basic components of a GC instrument and a flame ionization detector

    SLO2: Name and explain the factors that affect analyte retention and resolution in GC experiments.

    SLO3: Describe temperature programming and its benefits.


    Ch 24 – GC video

    Gas Chromatography (IQOG-CSIC). https://www.youtube.com/watch?v=iX25exzwKhI 

    This is the general setup of a gas chromatograph:

    GC_GeneralSetup.png


    Flame Ionization Detector (FID):

    • As organic analytes elute off the column and are combusted, CHO+ ions and electrons are generated and cause current flow between cathode and anode
    • Responds to most organic compounds (but not NO, O2, N2, CO2)
    • Sensitive (LODs in ng range)

    FlameIonizationDetector.png


    Tequila analyzed by GC using FID (top) and olfactory detection (bottom)

    Spectrum_Tequila.png


    Worksheet

    • Each student must fill in a worksheet.
    • Must be handed in before you leave.
    • It will be returned to you via Gradescope and will count as your clicker participation today.
    • The Key for the worksheet will be placed online.

    SLO1: Describe the basic components of a GC instrument and a flame ionization detector

    SLO2: Name and explain the factors that affect analyte retention and resolution in GC experiments.

    SLO3: Describe temperature programming and its benefits.


    In summary, we discussed the main factors that influence retention time and resolution in GC experiments:

    • Column temperature
    • Boiling point of analyte
    • Column composition

    You should be able to explain how and why these factors influence the retention time and resolution of an analyte.


    Conclusions / ToDo / Next Class

    • Read Chapter 24 section 24-1, and Flame Ionization Detectors in section 24-3

    Contributors and Attributions