chromatography

• What is chromatography?


  Chromatography is an analytical technique used to separate and identify component molecules of a mixture.
• What are the two phases involved in chromatography?


  The two phases are the mobile phase and the stationary phase.
• What is the role of the mobile phase in chromatography?


  The mobile phase allows molecules to move over or through the stationary phase.
• What forms can the mobile phase take in chromatography?


  The mobile phase can be in the form of a liquid or a gas.
• How does solubility affect the movement of products in chromatography?


  More soluble products move further with the mobile phase.
• What is the stationary phase in chromatography?


  The stationary phase is a substance that has affinity to molecules in the mixture being analyzed.
• How does the affinity of a molecule to the stationary phase affect its movement?


  The greater the affinity of a molecule to the stationary phase, the shorter the distance it moves with the mobile phase.
• What is an Rf value in chromatography?


  Rf value is unique to each different component molecule in the mixture being analyzed.
• How is the Rf value calculated?


  It is calculated by comparing the distance moved by the mobile phase and the molecule.
• What are the four main types of chromatography?

  1. Thin-Layer Chromatography
  2. Column Chromatography
  3. Gas Chromatography
  4. GC-MS (Gas Chromatography-Mass Spectrometry)
• What is the method used in Thin-Layer Chromatography?


  A metal plate is coated with a thin layer of silica and solvent moves up the plate.
• Why is the plate dried in Thin-Layer Chromatography?


  The plate is dried in a fume cupboard to reduce toxic fumes.
• How can chemical traces be viewed in Thin-Layer Chromatography?


  Chemical traces can be viewed using a UV lamp or by adding a developing agent like iodine.
• What is the setup for Column Chromatography?


  A vertical column is packed with a solid, powdered substance which acts as the stationary phase.
• How does the mixture move in Column Chromatography?


  A solvent containing the mixture is added and moves down the column as the mobile phase.
• What does the varying affinities of molecules in Column Chromatography allow?


  It allows them to drain out of the column at different times, collected as separate samples.
• What is retention time in chromatography?


  Retention time is the time taken for a molecule to drain out of the column.
• What is the setup for Gas Chromatography?


  A thin tube is packed with a solid, powdered substance which acts as the stationary phase.
• What is used as the mobile phase in Gas Chromatography?


  A high pressure gas is passed through the tube as the mobile phase.
• What type of mixtures is Gas Chromatography used to separate?


  It is used to separate mixtures of volatile liquids.
• How does the analysis machine in Gas Chromatography work?


  The analysis machine records a retention time for each component molecule in the mixture.
• What does GC-MS combine?


  GC-MS combines gas chromatography and mass spectrometry.
• What is the advantage of using GC-MS?


  GC-MS is a much faster analytical process that produces more accurate results for molecule analysis and identification.
• What are the key features of GC-MS?


  • Combines gas chromatography and mass spectrometry
  • Allows for advanced molecule analysis
  • Faster analytical process
  • Produces more accurate results