2. Fluorescence- Several heterocyclic compounds give fluorescence in UV due to presence of conjugate double bond system. TLC plate can be visualized in an UV-chamber (Figure 34.4) to identify the spots on TLC plate.

Figure 34.4: UV-Chamber and UV illuminated TLC plate.

Technical troubles with thin layer chromatography-

1. Tailing effect-In general sample forms round circular spot on the TLC plate. It is due to the uniform movement of the solvent front through out the plate. But in few cases instead of forming a spot, a compound forms a spot with long trail or rocket shape spot (Figure 34.5).  it is due to few reasons as given below: