Why was it important to make sure the spots on the TLC plate were above the solvent in the TLC chamber?

The solvent level has to be below the starting line of the TLC, otherwise the spots will dissolve away. Non-polar solvents will force non-polar compounds to the top of the plate, because the compounds dissolve well and do not interact with the polar stationary phase.

Why should spotting of mixture be done?

The sample spot will dissolve in the mobile phase and its components will move all over the plate resulting in no distinct separation. Hence, spotting of a mixture should be done to solvent the level of the mobile phase.

Why is it important to keep the spots applied to TLC slide for chromatography as small as possible?

keeping small spots on your silica plate (or whatever your immobile phase is) will allow for greater resolution between the spots allowing for more accurate Rf calculations and solvent separation/preparation if using to isolate a compound in a mixture.

When spotting samples they should be at least answer apart from each other on the plate?

If you are applying several different samples on the same plate, make sure their spots do not touch each other. Adjacent spots must be separated by a minimum distance of 0.5 cm, or they’ll run into each other during the separation.

Why must the spot applied to a TLC plate be?

Used to separate volatile components of a mixture with low B.P. Why must the spot be applied to the TLC plate above the level of development solvent? Low B.P. and thus more likely to evaporate off the plate before separation can occur.

Why must the spot be above the level of the development solvent in the developing chamber?

Why must the spots be above the level of development solvent in chamber? They will dissolve in the development solvent if they were submerged. A student spots an unknown sample of a TLC plate and develops it in dichloromethane solvent.

Why should the spot in chromatography be above the solvent?

The start line above the solvent level allows the solvent to move past the start line, carrying the dissolved samples along with it.

Why should porting of mixture be done above the level of mobile phase?

Textbook solution The stationary phase offers a suitable medium for separation of liquids. The mobile phase is a solvent. As a result of this, the components present in the mixture sample will not show accurate separation. Hence, sample spotting must be done above the level of the mobile phase.

Why is a small spot of pigment needed on a TLC plate?

Why might not all of the amino acids known to be present in the mixture have appeared on your chromatogram? Why is a small spot of pigment needed on the TLC plate? Use a different solvent and/or a different stationary phase, this means pigments which may have run together will separate out.

Why is it necessary to cover the developing chamber tightly during the development of a chromatogram?

The reason for covering the beaker is to make sure that the atmosphere in the beaker is saturated with solvent vapor. To help this, the beaker is often lined with some filter paper soaked in solvent. Saturating the atmosphere in the beaker with vapor stops the solvent from evaporating as it rises up the plate.

Why must the spot be applied to the TLC plate above the level of development solvent?[ 5 points?

What would happen if the level of the solvent came above the level of the spots at the start?

Experiment 5: Thin Layer Chromatography and Melting Point 62 4) What would happen if your solvent level is above the level of the initial spots? Answer: The spots would dissolve into the reservoir of eluting solvent.