Multiple choice

Given below are the Rf values of some amino acids in two different solvents. The chromatography was carried out using whatman paper and the mode was ascending.

   
Amino acid Rf value N – butanol – acetic acid – water
(4 : 1 : 5) N – butanol– pyridine water
(1 : 1 : 1)
Aspartic acid 23 20
Alanine 30 37
Glycine 23 29
Histidine 1 24
Leucine 70 60
Lysine 12 13
Tyrosine 45 63

The mixture of amino acids can be separated satisfactorily by

  1. using N – butanol – acetic acid: water solvent system (4 : 1 : 5)

  2. using N – butanol – pyridine – water solvent system (1 : 1 : 1)

  3. by 2 – D chromatography using both the solvent system one at a time

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Since some amino acids (like aspartic acid and glycine) co-migrate in one solvent but separate in another, two-dimensional chromatography is required. This technique uses two different solvent systems sequentially to achieve complete separation of all components.

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