As an example of how ILC can be used to monitor the progress of a separation by
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Question
As an example of how ILC can be used to monitor the progress of a separation by column chromatography consider the following hypothetical situation. A chemist found that a mixture of four components (A-D) could be separated on a silica gel TLC plate using 10% diethyl ether in hexanes as the eluting solvent. The mixture was then chromatographed on a silica gel column eluted with this same solvent mixture and 11 fractions of 15 mL each were collected. Thin-layer chromatographic analysis of the various fractions under the conditions stated above gave the results shown in the figure below. Assume the components align as A -D, with A at the top and D at the bottom of the TLC plate original mixture. According to these results which fractions should be combined to give pure samples of A, B, C, and D? What fraction numbers still contain more than one component? Indicate for these mixed" fraction numbers what components of the original mixture are present. 10 1 original mixtureExplanation / Answer
1. The fractions for which there is only single spot on TLC plate gives the pure compounds.
Fractions 1 and 2contain single spot with same Rf value to that of compound A (The top spot in mixture)
Fractions 5 and 6 contain single spot with same Rf value to that of compound B (Thesecond top spot in mixture)
Fraction 8 contains single spot with same Rf value to that of compound C (The second bottom spot in mixture)
Fractions 10 and 11 contain single spot with same Rf value to that of compound D (The bottom spot in mixture)
So, the above mentioned fractiones can be combined to get pure A,B,C and D.
Fractions 3 and 4 contain mixture of A and B as both of these show two spots (with same Rfs like A and B) on TLC
Fraction 7 contains mixture of B and C as both of these show two spots (with same Rfs like B and C) on TLC
Fractions 9 contains mixture of C and D as both of these show two spots (with same Rfs like C and D) on TLC
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