Identifying Pigments in Leaves is it essential that the liquid level stays below

Question

Identifying Pigments in Leaves is it essential that the liquid level stays below the chromatography paper is placed in the solvent. Think what happens if the liquid level is above the starting line. starting line when a 2. Explain why is it essential not to let the solvent to run all the way to the top of the paper (your data are likely to be meaningless if you do). is it essential to mark the solvent front as soon as you take the paper out of what happens if the liquid level is above the starting line the chamber. 4. Answer this question based on your results from part I (spimach), informati on about the and structures of pigments, cellulose, composition of petroleum ether, their polarity intermolecular forces. Which pigment has the highest retention factor? Why did this pigment moved the farthest up the paper? Which pigment has the lowest retention factor? Why did this pigment did not move high up the paper? simple paper chromatogram of a fresh spinach (while chlorophylls show up in p chromatograms of both frozen and fresh spinach). You may want to use information in Table 1 5. Explain why pheophytins show up in a chromatograms of frozen spinach, but ra

Explanation / Answer

thin layer chromatography

1. The liquid layer must always stay below the level of starting line on the plate otherwise the solutes would dissolve and go into solution, nothing would be left on the plate to run.

2. It is important not to run the solvent all the way to the top of plate as then we would not have the correct Rf values for the spots, Rf is defined as distance travelled by the solute to that of the solvent.

3. Marking the solvent front allows us to accurately calculate the Rf value of the spots.

4. spinach pigment analysis by tlc

highest retention factor is seen for carotene

Carotenes are the least polar among all the pigments and hence moves farthest on the tlc plate.

5. In fresh spinach at room temperature, pheophytin moves together with chlorophyll (same polarity) and thus is mot seen on the plate, whereas, when we lower the temperature of spinach, the rate of movement of solvent also changes and we get difference between pheophytin and chlorophyll. Such an effect is not seen for chlorophyll.

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