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Spotting

Development

Visualisation

Sample dissolved in a volatile solvent = dilution (1%) solution.

Micro pipet transfers a small amount of dilute solution to one end of TLC.

Spotting solvent then evaporates, leaving a small spot of the material.

TLC

Bottom of TLC plate placed into a shallow pool of development solvent, then travels up the plate through capillary action.

As it travels up, it moves over the original spot.

Very polar silica gel tries to hold the spot in the original spot.

Solvent tries to move the spot along with it as it travels.

Outcome depends on a balance among three polarities: the plate, development solvent and spot material

Different components in the original spot, having different polarities, will move

different distances from the original spot location and show up as separate spots.

If coloured compounds, sports can be directly observed.

If colourless, the silica gel has a fluorescent material that glows under UV light.

Spot will appear dark on a glowing background. Spots can be outlined with pencil.

Once solvent has travelled, the plate is removed and the solvent front is marked with pencil. Solvent is left to evaporate.