Separate the mixture.
Chromatography separates species because they distribute differently between a moving phase and a stationary phase. Stronger attraction to the stationary phase tends to slow movement; greater preference for the mobile phase tends to carry a species further.
Rf is the distance from the baseline to the spot centre divided by the distance from the baseline to the solvent front. It has no units and normally lies between 0 and 1. Compare values only under the same conditions.
A matching Rf supports an identification but is not conclusive by itself: different species may have similar values. Run standards alongside the unknown and use complementary evidence where possible.
Read the chromatogram
Illustrative TLC plate with a solvent-front distance of 60 mm. Measure from the same baseline. Rf has no units.
Assumed knowledge
Ratios cancel matching distance units.
Learning checkpoints & source
YOUR SYLLABUS CHECKPOINT- Explain mobile and stationary phase interactions.
- Calculate and compare Rf values.
- Interpret separation evidence with limitations.