Question

Thin Layer Chromatography:

If a TLC plate is developed until the solvent front reachers the top of the plate, can it be used to determine an Rf value? Please Explain

Answer 1

In thin layer chromatography (TLC) the Rf values is a measure of distance travelled by the solute upon the distance travelled by the solvent from the origin to the solvent front marked. The efficiency of a chromatographic separation is dependent on the accuracy of measurement of these distances. If however, the solvent is allowed to run to the top of the tlc plate beyond the makred line, the accuracy of this distance measurement is lost due to unsurety of distance between origin and the level to which solute or the solvent has run. Leading to errors in the Rf value and poor chromatographic results therefore. Hence, we cannot measure Rf value If the solvent has run to the top of the tlc plate.