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TLC Procedure

The procedure of performing a TLC experiment is outlined in detail below:

A TLC development chamber, a TLC plate is inside a covered beaker with a circular filter paper behind it. The TLC plate has a line drawn approximately 1.5 cm from the bottom of the plate, and a black sample dot on the center of this line. A small amount of solvent is present in the beaker, reaching just under the sample spot.

Fig 1: TLC Development Chamber setup.

  1. After determining your solvent system, add around 1 cm of solvent to a beaker.

  2. Add a filter paper to the beaker - where the bottom of the filter paper is submerged in the solvent and it reaches the top of the beaker.

  3. Cover the beaker with a lid or watch glass. This ensures the volatile solvent does not evaporate from the beaker.

  4. Mark a straight line, 1.5 cm from the bottom of the TLC plate in pencil. Add a mark and label under the baseline where each sample will be spotted onto the plate - making sure not to touch the silica plate's surface or press too hard with the pencil.

  5. Using a capillary tube, spot a small amount of the sample in a concentrated area on the TLC plate at the correct marking. Let the spot dry and spot again 2-3 times to ensure a sufficient amount of sample is present. Repeat this process for each sample.

  6. Place the TLC plate carefully into the developing chamber with a pair of tweezers or forceps, ensuring the baseline is not submerged into the solvent. If this occurs, you have added too much solvent.

  7. Cover the TLC chamber and allow the mobile phase to be drawn up the TLC plate through capillary action.

  8. Remove the TLC plate from the chamber, when the solvent front is approximately 1 cm from the top of the TLC plate. Allowing the TLC plate to dry before proceeding to analysis.