Question

Why should spotting of mixture be done above the level of mobile phase
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Answer 1

Answer:

It is because if the mixture gets in contact with the solvent initially, it dissolves and gets washed off in the solvent before traveling up the plate. Ideally, the solvent layer should rise gradually by capillary action and along with it, the sample mixture should also travel up the thin layer chromatography plate.

Answer 2

Answer:

In thin-layer chromatography( TLC), the sample mixture should be spotted above the solvent level. It is because if the mixture gets in contact with the solvent initially, it dissolves and gets washed off in the solvent before traveling up the plate.

Ideally, the solvent layer should rise gradually by capillary action and along with it, the sample mixture should also travel up the thin layer chromatography plate.