When using chromatography, why do some experiments work with ethanol as the solvent but not with water?

Question

Help will be appreciated.

Answer 1

The principle of chromatography is separation, where you have a mobile phase and a stationary phase. To get effective separation, your eluents have to have varying interactive properties with both phases, such that different eluents will travel different distances and/or speeds. Some sets of compounds may either move too far with water such that they don't separate before coming off your column/paper, while other sets may not move at all. Ethanol may provide enough of a difference between compounds of interest.