Retention Factor (Rf) Calculator
Rf from a TLC plate, with what the value implies.
Work out Retention Factor (Rf). Rf from a TLC plate, with what the value implies. Free, with no account and nothing to download.
From the baseline to the centre of the spot.
Retention factor (Rf)
0.500
well resolved — in the useful range
Rf is always between 0 and 1, and it is only meaningful alongside the plate, solvent and temperature it was measured with — the same compound gives a different Rf in a different solvent system. On a normal silica plate the stationary phase is polar, so polar compounds stick and travel a short distance, giving a low Rf. Reverse-phase plates invert that. A useful separation usually puts spots between about 0.2 and 0.8; anything riding the solvent front or stuck on the baseline needs a different solvent.
How the Retention Factor (Rf) Calculator works
Measure how far the spot travelled and how far the solvent front travelled, and this gives the Rf along with what that value says about the compound's affinity for the plate. Both distances are measured from the pencil baseline, and the spot is measured to its centre.
Also known as: rf value calculator · tlc calculator · chromatography rf calculator · how to calculate rf value
Frequently asked questions
How do I calculate an Rf value?
Divide the distance the spot travelled by the distance the solvent front travelled, both measured from the baseline. It is always between 0 and 1 and has no units.
What does a high Rf mean?
That the compound barely interacted with the plate and travelled almost as far as the solvent. On normal silica, which is polar, that means a non-polar compound. A low Rf means it stuck to the plate, so it is polar.
Why is my Rf different from the literature value?
Rf depends on the solvent system, the plate, the temperature and how far the solvent was allowed to run. It is only comparable within one experiment, which is why you run a known standard on the same plate rather than trusting a published number.
What Rf should I aim for?
Between roughly 0.2 and 0.8. Spots at the baseline or riding the solvent front are not separated from anything, so adjust the solvent polarity and run it again.
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