Retention factor

Retardation factor, or R_f, is a concept in chromatography and is calculated as the simple ratio:

$\ R_{f}={\frac {\mbox{Migration Distance of Substance}}{\mbox{Migration Distance of Solvent}}}$

In most cases, the paper used to measure retention factor is polar, (due to the nature of cellulose in paper), allowing one to deduce the relative polarity of a substance being moved by the polar solvent.

The higher, or closer to 1, the ratio is, the less polar the substance being measured is.

The methods whereby retention factor can be calculated include: paper chromatography, column chromatography.