Thin layer chromatography is a technique used to separate non-volatile mixtures. It involves a stationary phase, such as a coated sheet of glass or aluminum, and a mobile phase, which is a liquid solvent. The sample is dissolved and spotted on the stationary phase. The mobile phase then travels up the stationary phase by capillary action, carrying the sample components with it. Their separation depends on the relative polarities of the sample components and the phases. The separated components are then visualized using ultraviolet light or iodine vapors and identified by their retardation factor.

1. Thin layer chromatography

2. Thin-layer chromatography (TLC):
is a chromatography technique used to
separate non-volatile mixtures.

3. Thin layer chromatography components:

4. stationary phase
• on a sheet of glass, plastic, or aluminium foil, which is coated with a thin
layer of adsorbent material, usually silica gel, aluminium oxide (alumina),
or cellulose.This layer of adsorbent is known as the stationary phase.

5. mobile phase
• The mobile phase is a suitable liquid solvent or mixture of solvents.
The mobile phase flows through the stationary phase and carries the
components of the mixture with it.

6. Stationary phaseVS Mobile phase

7. Continue…..

8. Steps…
• First the sample to be analyzed is dissolved in a
volatile (easily evaporated) solvent to produce a
very dilute (about 1%) solution.

9. TLC consists of three steps - spotting,
development, and visualization.

10. spotting
• Spotting consists of using a micro pipet to transfer a small
amount of this dilute solution to one end of a TLC plate, , in
this case a thin layer of powdered silica gel that has
been coated onto a plastic sheet.
•The spotting solvent quickly evaporates and leaves
behind a small spot of the material.

12. Development
•consists of placing the bottom of the TLC plate into a
shallow pool of a development solvent, which then
travels up the plate by capillary action.
•As the solvent travels up the plate, it moves over the
original spot. A competition is set up between the
silica gel plate and the development solvent for the
spotted material.

13. Development….

14. CONTINUE…
•The outcome depends upon a balance among
three polarities - that of the plate, the
development solvent and the spot material.

15. Visualization
• First method The silica gel on the TLC plate is impregnated with a
fluorescent material that glows under ultraviolet (UV) light. A spot will
interfere with the fluorescence and appear as a dark spot on a glowing
background.

16. A second method of visualization is accomplished by
placing the plate into iodine vapors for a few minutes
Most organic compounds will form a dark-colored
complex with iodine.

17. Retardation factor (Rf) :
•the distance traveled by the substance being
considered is divided by the total distance traveled
by the mobile phase.
•In general, a substance whose structure resembles
the stationary phase will have low (Rf) ,while one that
has a similar structure to the mobile phase will have
high (Rf) .

19. • If a development solvent of too high a polarity is used, all
components in the mixture will move along with the solvent
and no separation will be observed (Rf’s will be too large). If
the solvent is of too low a polarity the components will not
move enough, and again separation will not occur (Rf’s will
be too small). In practice, different solvents or mixtures of
solvents are tried until a good separation is observed.
Typically an effective solvent is one that gives Rf's in the
range of 0.3 - 0.7.

20. EX:

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‫عبدهللا‬ ‫محمود‬ ‫دنيا‬
‫حلمي‬ ‫السيد‬ ‫دينا‬
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Sec : 5 from11-15‫عبدالفتاح‬ ‫محمد‬ ‫دينا‬