3.3.16 Chromatography
Chromatography provides an important method of separating and identifying components in a mixture.
Different types of chromatography are used depending on the composition of mixture to be separated.
Chromatography can be used to separate and identify the
components in a mixture.
Types of chromatography include:
•• thin-layer chromatography (TLC) - a plate is coated with
a solid and a solvent moves up the plate
•• column chromatography (CC) - a column is packed with
a solid and a solvent moves down the column
•• gas chromatography (GC) - a column is packed with
a solid or with a solid coated by a liquid, and a gas
is passed through the column under pressure at high
temperature.
Separation depends on the balance between solubility in
the moving phase and retention by the stationary phase.
Retention times and Rf values are used to identify different
substances.
The use of mass spectrometry to analyse the components
separated by GC.
Students should be able to:
•• calculate Rf values from a chromatogram
•• compare retention times and Rf values with standards to
identify different substances.