Question

In the chromatographic separation of photosynthetic pigments, which of these is represented by a, b, c and d respectively.

• A. a - chlorophyll b; b - carotene; c - chlorophyll a; d - xanthophyll
• B. a - chlorophyll a; b - carotene; c - chlorophyll b; d - xanthophyll
• C. a - carotene; b - xanthophyll; c - chlorophyll a; d - chlorophyll b
• D. a - xanthophyll; b - carotene; c - chloropyhll b; d - chlorophyll a

Answer 1

Answer: (C)

• The mobile phase has a migrating moisture line of wetness, which is called the solvent front.
• As the solvent travels over the spot, each of the pigments will travel with the mobile phase at different rates from the original spot. Some pigments will adhere to the paper more strongly than others, and thus travel shorter distances along with the paper.
• Chlorophyll b travels the least distance with the mobile phase. Chlorophyll b is a more polar pigment than the other pigments and is more strongly attracted to the polar surface of the paper than to the nonpolar solvent.
• The remaining pigments travel increasing distances with respect to chlorophyll b, beginning with blue-green chlorophyll a, followed by yellow-orange xanthophyll and finally the orange pigment of carotene.
  
• Carotene moves the farthest because it is the most non-polar of the pigments.