Question

I am writing about an experiment, were were given the results. It has to do with TLC. In this experiment we are trying to find the composition of lipids in erythrocytes, butter and Egg yolk. To do this experiment we have one stationary phase (and aluminium sheet coated with silica gel), and two mobile phases (Solvent 1 is polar, solvent 2 is not very polar/ non polar). Why do we have these two different mobile phases? I noticed that in solvent 1, the TLC picked up phospholipids (PE,PC, and SM). However in solvent 2, it picked up cholesterol and 2 unidentified substances. What kind of lipids does solvent 2 attract, and why does solvent 1 only attract phospholipids?

Answer 1

Ans- Two different solvents were taken to dissolve or seperate two different molecules i.e phospholipids (amphipathic molecule ) and cholesterol and cholesterol like molecule i.e non-polar.

By the fact, LIKE DISSOLVES LIKE. A polar solvent will dissolve polar substance and non-polar solvent will dissolve non-polar substance.

The solvent 1 may be a polar solvent that because of phospholipid polar head, dissolved these into itself and picked up these only. Example- Ethylene glycol, methanol

The solvent 2 may be non-polar solvent that dissolved and extracted cholesterol, a non-polar molecule and other two unidentified molecules, that may also be non-polar. Example- Floroalkanes, cyclohexane.