Effect of the distance moved by the solvent on the rf values in circular chromatography

1. The effect of the distance travelled by the solvent on the R_F values of the amino acids subjected to circular paper chromatography has been studied under various conditions with two solvents: (i) Phenol-water, which is less volatile and (ii) butanol-acetic acid-water which is more volatile. The R_F values with both the solvents are almost independent of the distance travelled by the solvent. It is essential in all these experiments to control perfect saturation inside the chamber in order to get reproducible R_F values. 2. The increase in R_F values reported by RAO and GIRI¹ with distance of travel of the solvent appears to be clue to lack of necessary saturation inside the chamber. The same defect seems to liave vitiated the experiments of rao and BERI⁶ wlio also reported very high R_F values. 3. Butanol-acetic acid-water of the composition 4 : 1 : 1⁹ is suggested as a good solvent for practical purposes.