Cambridge IGCSE Chemistry · Syllabus 0620 · Experimental Techniques and Chemical Analysis
Retention Factor
What is Retention Factor?
The retention factor, Rf, is the distance travelled by a substance divided by the distance travelled by the solvent, with both distances measured from the same baseline. Because it is a ratio of two lengths it has no unit, and for an ordinary chromatogram its value lies between 0 and 1. Rf depends on the solvent and conditions as well as on the substance, so values are only compared between chromatograms run under the same conditions.
This definition is part of the Experimental Techniques and Chemical Analysis chapter in Cambridge IGCSE Chemistry.