What is the range of Rf values?

What is the range of Rf values?

• A. 0 < Rf ≤ 1
• B. 0 ≤ Rf ≤ 1
• C. 0 < Rf < 1
• D. Rf > 1

Answer: (A)

Rf is defined as the distance moved by a compound divided by the distance moved by the solvent front in thin-layer chromatography. Since both distances are nonnegative and the solute cannot move farther than the solvent front under the same conditions, the ratio cannot be negative and cannot exceed 1. In practice, the solute typically moves some distance, giving a value greater than zero, while it can reach the solvent front in the extreme case, giving a value of 1. Therefore the range is between zero and one, with 1 possible and 0 typically not included in standard ranges. Hence 0 < Rf ≤ 1.

Rf is defined as the distance moved by a compound divided by the distance moved by the solvent front in thin-layer chromatography. Since both distances are nonnegative and the solute cannot move farther than the solvent front under the same conditions, the ratio cannot be negative and cannot exceed 1. In practice, the solute typically moves some distance, giving a value greater than zero, while it can reach the solvent front in the extreme case, giving a value of 1. Therefore the range is between zero and one, with 1 possible and 0 typically not included in standard ranges. Hence 0 < Rf ≤ 1.