Chromatography

Introduction to Chromatography

• Chromatography is a method for separating mixtures.
• Relies on a mobile phase (liquid or gas) and a stationary phase (solid or liquid).

Paper Chromatography

• Stationary Phase: Paper
• Mobile Phase: Solvent (e.g., water or organic solvent)
• Process:
  • Draw a line on paper and add a sample.
  • Place paper in a container with solvent.
  • Solvent travels up the paper, separating dyes/components based on polarity.
  • Components that are more attracted to the solvent travel further.
• Used to identify components in a mixture.

Thin-Layer Chromatography (TLC)

• Similar to paper chromatography.
• Stationary Phase: Silica gel on a glass slide.
• Mobile Phase: Solvent
• Commonly used in organic chemistry labs for preparative purposes.

Column Chromatography

• Stationary Phase: Packing material (e.g., silica gel)
• Mobile Phase: Organic solvent
• Separation based on polarity.
• Sample introduced into a column; solvent moves compounds into bands.

Size-Exclusion Chromatography

• Stationary Phase: Beads with holes
• Process:
  • Small compounds travel faster through beads.
  • Large compounds take longer.

Ion-Exchange Chromatography

• Beads: Charged groups
• Process:
  • Compounds with the same charge are repelled and travel fast.
  • Oppositely charged compounds bind tightly and move slowly.

Affinity Chromatography

• Relies on specific binding interactions (e.g., enzyme-substrate)
• Process:
  • Specific compounds bind tightly to columns.
  • Non-specific compounds are washed away.
  • Specific compounds can be eluted with a more attractive solution.

High-Performance Liquid Chromatography (HPLC)

• Advanced form of column chromatography.
• Smaller quantities and higher sensitivity.
• Used for precise separations.

Gas Chromatography

• Stationary Phase: Liquid
• Mobile Phase: Carrier gas
• Process:
  • Sample vaporized and passed through a heated chamber.
  • Separation based on volatility and boiling points.
• Suitable for separating compounds with different boiling points.

Summary

• Chromatography is a versatile technique used for separating and analyzing compounds in mixtures.
• Various types exist, each with unique advantages depending on the properties of the components.