Chromatography is a technique in which components of a mixture are separated by distributing them between two phases, a stationary phase, and a mobile phase. Different components of a mixture are separated because they have different affinities for the stationary and mobile phases. Paper chromatography is a technique in which filter paper is used for the absorption of water phase Water molecules absorbed in the paper act as a stationary phase and the solvent act as mobile phase. Paper is used to supporting the stationary phase in paper chromatography.
Rf is the Retardation factor. It is the ratio of the distance travelled by solute from the baseline to the distance travelled by solvent from the baseline.
Chromatographic paper, chromatographic tank or cylinder, the capillary tube with a jet, glass rod etc.
Blue, green and red inks, n-butanol, ethanol and ammonia.
n-butanol, ethanol and ammonia in the ratio of (3:1:3) or ethanol and water in the ratio (1: 3).
- A 3 x 15 cm strip of chromatographic paper was taken.
- A thin baseline was drawn with a lead pencil about 2 cm above the edge of the paper.
- The solvent was prepared by mixing 85 cm3‘ ethanol and 15 cm3‘ distilled water and placed in the chromatographic cylinder or tank.
- A drop of a mixture of inks was placed at the baseline on the strip with the help of capillary jet.
- The strip was dried and suspended in the solvent.
- When solvent reached about 3/4th of the strip, the strip was removed from the solvent and dried.
- The distance travelled by inks and the solvent was marked.
- The Rf, value for each ink was calculated.
Observations and calculations.
Distance travelled by solvent = cm
The mixture of inks was separated and Rf, values of inks were calculated.