1. Chromatography
prepared by
M.Haris
9-’o’

2. 1.Paper Chromatography
• Paper chromatography is a technique that involves
placing a small dot of sample solution onto a strip of
chromatography paper.
• Different compounds in the sample mixture travel at
different rates due to:
i. differences un solubility in the solvent.
ii. differences in their attraction to the fibers in the
paper.

4. Paper Chromatography-
Procedure
1. The paper is placed in a jar containing a solvent such as
ethanol or water then sealed.
2. A small concentrated spot of solution that contains the
sample of the solute , is applied to a strip of
chromatographic paper about 2cm away from the base
of plate.
3. As the solvent rises through the paper, it meets the
sample mixtures which starts to travel up the paper
with solvent.

5. Paper Chromatography-
Procedure
4. Paper chromatography takes from several minutes to
several hours.

6. Paper Chromatography
Ascending
• In this method the solvent moves upward against
gravitational force.
• The only force that cause the motion is capillary force. So
the speed of the process is slow.

8. Paper Chromatography
Descending
• In this method, the solvent is kept in a trough at the
top of chamber and is allowed to flow down the paper.
• The liquid moves down by capillary action as well as
the gravitational force.
• In this case, flow is more rapid as compared to the
ascending method. Because of this rapid speed the
process is completed in a shorter time.
• The developing solvent is placed in a trough at the
which is usually made up of an inert material.

10. Rf Value
(Retention Factor)
• Rf =
• If Rf value of a solution is zero the solute remains in
the stationery phase and thus it is immobile.
• If Rf value = 1 then the solute has no affinity for the
stationery phase and travels with the solvent front.
• The final chromatogram can be compared with other
known mixture chromatograms to identify sample
mixes, using the Rf value in an experiment.
ratio of the distance travelled by the sububstance
the distance travelled by the solvent