Miss Fogg
2015
Chromatography
 Chromatography (from Greek word for chromos for
color) is a laboratory technique for the physical
separation of a mixture into its individual
components
Mixtures & Compounds
 A mixture = a collection of 2 or more pure
substances that are physically close together but
not chemically combined
 A compound = 2 or more elements that are chemically
combined
Types of mixtures
Solutions
 Solutions have 2 parts: solute & solvent
 Solute: the substance that is dissolved
 Solvent: the substance that does the dissolving
Solutions
 Identify the solute and solvent in each solution…
Lemon juice, sugar
Water
Sugar, coloring…
Water
Salt, ions…
Water
Solubility
 Solubility = a measure of how much of a given
substance will dissolve in a liquid.
 A substance that does not dissolve in water is called
insoluble  results in a suspension
 A substance that does dissolve in water is called soluble 
results in a dissolved solution
How Chromatography Works
 Parts of a mixture will be separated based on their
affinity to the solvent
 AFFINITY: Does the solute “like” the solvent?
Chromatography
 We can separate the components of a mixture in a
variety of ways…
 Types of Chromatography:
 Liquid
 Thin-layer
 Gas
 Paper
Liquid Chromatography
 Used to identify unknown plant pigments & other
compounds
Thin-Layer Chromatography
 Uses thin plastic or
glass trays to identify
the composition of
pigments, chemicals,
and other unknown
substances.
Gas Chromatography
 Used to determine the chemical composition of
unknown substances, such as the different compounds
in gasoline shown by each separate peak in the graph
below.
Paper Chromatography
 Can be used to separate the
components of inks, dyes,
plant compounds
(chlorophyll), make-up, and
many other substances
How Chromatography Works
Check your understanding…
 Can chromatography procedures be used to separate…
 A mixture?

It depends – only homogeneous mixtures
 A compound?

NO – this would require a chemical change
 A dissolved solution?

Yes – into solute and solvent
Use of Chromatography
 Chromatography can be used to
 Separate the different colored components that make up
black ink
 Detect tiny amounts of drugs or certain chemicals in
urine samples
Chromatography Lab
 Forensic scientists can determine whether a document
contains 2 or more different kinds of ink
 Different types of water-soluble ink pens vary in their
compositions (the mixtures are unique to the brand
that manufactures them)
 Unique mixtures will separate differently on the
chromatograph
Check your understanding
 What type of chromatography procedure is shown
below:
Paper Chromatography
Chromatography Lab
 We will use paper chromatography to investigate the
components of inks
 The final product is called a “chromatograph”
 RF value
 How chromatography works
 Why solvent moves up the paper
 Affinity