Chromatography???

Question

can someone please explain rf values in simple terms. thanks

Answer 1

Rf = distance run by pigment (distance from pencil dot to top end of pigment)      divided by

       distance run by solvent (should be distance between the two pencil lines)

see image on this site:

http://orgchem.colorado.edu/hndbksupport...

The Rf value of pigments will vary if different solvents or chromatography material is used. Even very small changes in the composition of the solvent will result in different Rf values. The solvent must also be fresh as different rates of evaporation of the components will change its composition.