Thin Layer Chromatography: A Complete Guide to TLC

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• add a spatula or Pasteur pipette tip and dissolve it in a bit of solvent!

• few miligrams of mixture/compound in around 0.5–1 mL of solvent

• Try to spot your mixtures as tightly as possible. Make very small spots of sample. Very wide spots will make the different compounds overlap leading to a not so nice separations

• 0.5 cm height of the desired solvent system

• If none of this works, you are looking at a extremely polar compound and you might want to consider using reverse phase

• retention factors depend greatly on the solvent system used and on the stationary phase of the TLC.

• You need the atmosphere as saturated as possible.

• so the solvent doesn’t evaporate and allows for a nice saturated atmosphere

• Why? The solvent will ascend through the filter paper as well (by the same principle than through the TLC), helping a lot in saturating the atmosphere inside the chamber with the eluent. This will make the eluent go up the TLC plate in a much more even manner.

• small changes in functionalities on organic compounds lead to a change in the color of the TLC plate after vanillin staining and heating. This is really great if your starting material and product have a very close Rf.

• it shows brightly most compounds with polar functional groups.

• when pairing solvent mixtures, try to go for solvents with similar volatility, so you don’t get faster evaporation of one of the components of the mixture than the other. This can potentially lead to reproducibility issues.

• a chromatography is any lab technique in which we separate different chemical components of a mixture by their affinity to a stationary phase (usually silica gel in TLC) and to a mobile phase (the solvent or mixture of solvents).

• thin layer chromatography, or TLC

• TLC, we use a stationary phase (most frequently silica gel) which is deposited over a glass or aluminum support.