Visualising plates

UV-Vis

UV light is usually used first to visualise TLC plates. There are two ways this can work. Most commonly the TLC plate being used has a fluorescent compound bound into the stationary phase of the plate. The presence of any compound on the plate quenches the fluorescence, leading to a darkened area on the plate. Alternatively plates without a fluorophore can be used with compounds which fluoresce, leaving the plate dark except in areas where compound is present.

Visual

For some highly coloured compounds it is possible to directly visualise compounds on the plate, but this is not very common.

Stains

A number of stains are routinely used to aid visualising TLC plates. The choice of stain is dependent on what compounds are being observed on a TLC plate.