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Study Notes: Classification of Chromatographic Methods

Chromatographic methods can be differentiated based on the physical means of bringing the stationary and mobile phases into contact -

Column Chromatography - the stationary phase is held in a narrow tube through which the mobile phase is forced either by pressure or by gravity.
Examples include:

  • Simple column chromatography
  • High pressure liquid chromatography (HPLC)
  • Gas chromatography (GC).

Planar Chromatography - the stationary phase is supported on a flat plate or in the fibres of a paper. Here the mobile phase moves through the stationary phase by capillary action or by gravity.
Examples include:

  • Paper chromatography
  • Thin layer chromatography (TLC).

Column chromatography can be further differentiatedbased on the types of stationary and mobile phases and the kinds of equilibria involved in solute transfer between the phases.

There are two broad categories in this classification scheme:

  • Liquid chromatography (for instance simple column or HPLC)
  • Gas Chromatography (GC).

The table that follows shows how these categories can be further classified (adapted from Table 24.1 - Skoog, DA & Leary JJ. (1992). Principles of Instrumental Analysis 4th edition. Saunders College Publishing: Fort Worth).

General Classification
Specific Method Name
Stationary Phase
Type of Equilibrium
Liquid Chromatography (LC)
Mobile Phase = liquid
Liquid-liquid or partition Liquid adsorbed on a solid Partition between immiscible liquids
Liquid-bonded phase Organic species bonded to a solid surface Partition between liquid and a bonded surface
Liquid-solid or adsorption Solid Adsorption
Ion exchange Ion-exchange resin Ion exchange
Size exclusion Liquid in interstices of a polymeric solid Partition/sieving
Gas Chromatography (GC)
Mobile Phase = gas
Gas-liquid Liquid adsorbed on a solid Partition between gas and liquid
Gas-bonded phase Organic species bonded to a solid surface Partition between liquid and bonded surface
Gas-solid Solid Adsorption

For a definition of the many terms used in this table, consult the Glossary.

There are many different forms of chromatography and whilst this unit will concentrate on HPLC and GC you should at least be aware of the other forms of chromatography and some of the basic differences between the methods.

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