Choosing the right layer in TLC

The eluent, the type of application and sample preparation are not the only criteria for successful thin-layer chromatography (TLC). The choice of the right TLC layer also contributes significantly to the quality. The selection here is large so that some help is given in the following:

Silica gel in normal phase (NP) TLC

It is worth mentioning that TLC as well as HPLC can be used as a normal phase or a reverse phase system. In normal phases, the most common stationary phase is the silica gel. Its stability over a wide pH range and the high selectivity with a large number of different solvents allows a wide range of applications. Normal phase (NP) TLC is mainly used for adsorption chromatography separations.

Phases in reverse phase (RP) TLC

The supply of stationary phases is broader for reverse phase TLC: in addition to the silica gel as a polar phase, non-polar phases such as RP-18 or medium-polar phases such as RP-2 or aminopropyl or cyanopropyl phases can also be used. Regarding silica gel plates, a prior activation should generally be renounced if it is not specifically required. This results in an initial state which restricts the reproducibility of the results.

Lichrospher as an alternative

In addition to the above-mentioned phases, Lichrospher offers another option. The spherical shape of the 5 μm small particles allows an extremely high separation quality with shortened running time. Therefore, Lichrospher-Si-60 layers are recommended for quantitative work.