Chromatography

• What is chromatography?

  An analytical technique for separating mixtures
• What are the two phases involved in chromatography?

  Mobile phase and stationary phase
• What can the mobile phase be in chromatography?

  A liquid or a gas
• What types of stationary phases are used in chromatography?

  A solid or a liquid on a solid support
• How does a solid stationary phase separate components?

  By adsorption
• How does a liquid stationary phase separate components?

  By relative solubility
• What happens when a polar stationary phase is used with a non-polar mobile phase?

  Non-polar compounds pass through quickly
• What does separation in column chromatography depend on?

  Solubility in the moving phase and retention
• What is the mobile phase in gas-liquid chromatography (GC)?

  An inert gas like nitrogen or helium
• What is the stationary phase in gas-liquid chromatography (GC)?

  A liquid on an inert solid
• What are the types of chromatography?

  • Thin-layer chromatography (TLC)
  • Column chromatography (CC)
  • Gas chromatography (GC)
• What is the purpose of retention times and Rf values in chromatography?

  To identify different substances
• What is the first step in thin-layer chromatography (TLC)?

  Draw a pencil line on the TLC plate
• Why should the pencil line be above the solvent level in TLC?

  To prevent dissolving the sample spots
• What is the purpose of wearing gloves during TLC?

  To prevent contamination from hands
• What is the formula for calculating Rf values?

  Rf = distance moved by amino acid / distance moved by solvent
• What is the purpose of drying the TLC plate in a fume cupboard?

  To handle toxic solvents safely