Chromatography Lecture Notes

Overview of Chromatography Types

• Partition Chromatography

  • Liquid-Liquid Chromatography
    • Liquid stationary phase retained by physical adsorption.
    • Common issue: loss of stationary phase due to dissolution in mobile phase.
  • Bonded Phase Chromatography
    • Supports made from rigid silica composition.
    • Difference from liquid-liquid: method of retaining stationary phase.

• Adsorption Chromatography (Liquid-Solid Chromatography)

  • Stationary phase typically silica or alumina.
  • High sample capacity allows for greater sample passage.

• Ion Exchange Chromatography

  • Uses ion exchange resin (cationic or anionic).
  • Process involves exchanging ions (e.g., protons for calcium).
  • Used for separating ionic compounds.

• Size Exclusion Chromatography (Gel Chromatography)

  • Stationary phase is a gel with controlled pore size.
  • Separates molecules based on size and shape.
  • Applicable for high molecular weight species.

Comparison of Chromatography Types

• Choice of type depends on molecular weight and polarity.
• Liquid Chromatography (LC): Widely used analytical technique.
  • Advantages include increased sensitivity and suitability for non-volatile species.

Liquid Chromatography (LC) Specifics

• Discussion on High Performance Liquid Chromatography (HPLC).

Van Deemter Equation

• Equation: H = A + B/μ + Cμ
  • A: Eddy diffusion (independent of flow rate).
  • B: Longitudinal diffusion (inverse proportional to flow rate).
  • Cμ: Mass transfer (directly proportional to flow rate).
• Reducing particle size increases efficiency by decreasing plate height.

Column Efficiency in LC

• Efficiency increases with smaller particle sizes and reduced radius of the column.
• Extra column band broadening affects efficiency, related to flow rates and packing.

Sample Size and Efficiency

• Increase in sample size results in increased plate height, decreasing efficiency.

HPLC Instrument Components

• Overview
  • Includes components like solvent reservoirs, sparger, and inlet filter.
  • Discussed components including guard and analytical columns.
• Solvent Systems
  • Isocratic Elution: Single solvent of constant composition.
  • Gradient Elution: Uses multiple solvents with varying polarity.
  • Advantages of gradient elution include reduced separation time without resolution loss.

Final Notes

• Importance of conditions in HPLC analysis, such as type of elution, columns, and conditions.
• Upcoming lecture to cover more on HPLC instruments and related exam schedule.