Two reasons why two substances that run on a chromatography column do not separate as defined bands.
A spot of a sample whose retention factor is 0.95 is observed. Does this indicate that the unknown material is a pure compound? If it is not a pure compound, how can purity be verified?
Why is it important to let the level of the eluent in the column lower to the level of the sand before applying the solution of the compound to be separated? What effect would this have on the efficiency of the separation?