Gas Chromo

• Use of gas chroma

  Separate components and identify then, but is really expensive
• Moving phase is a

  Gas
• Describe the process

  Tube coiled up in an oven, stationary phase is a powder which is coated in a viscous liquid, sample is vapourised then injected, carried along by moving phase
• What is the moving phase

  Unreacted gas
• Example of the moving phase

  Helium or nitrogen
• What is the stationary phase

  Powder coated in a viscous liquid
• Due to the moving phase

  It doesn't consider affinity between components and the moving phase, but considers affinity between components and the stationary phase
• If the stationary phase is polar, how can we have a high retention time

  The component must be polar
• Why is the long tube coiled up in an oven

  To control the temperature
• Cons of gas chroma

  Expensive
• How to have a low retention time if the stationary phase is polar

  Component must be non-polar which allows it to pass through the tube faster
• What happens when molecules reach end of the tube

  They are detected by a detector
• What does the detector do

  Produced a graph, gas chromatogram
• What does the height of the peak show

  How much is eluted
• What does the width of the peak show

  How long it has eluted for
• What does the area tell us

  Abundance
• What does the most abundant area tell us

  More molecules pass through there
• If the stationary phase is non-polar and the component is non-polar

  Higher retention by the stationary phase, greater retention time