Why is the start line needed in chromatography?

In paper chromatography, a starting line in drawn on the paper in pencil (pencil so that it does not dissolve in the solvent and affect the results). For example, in paper chromatography, if a substance is more strongly attracted to the solvent than the paper then it will move a long way with the solvent.

Why should the water be below the start line in chromatography?

It is important that the solvent level is below the line with the spots on it. The reason for covering the container is to make sure that the atmosphere in the beaker is saturated with solvent vapour. Saturating the atmosphere in the beaker with vapour stops the solvent from evaporating as it rises up the paper.

Why is it important to have the solvent in the developing chamber be below the starting line?

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 the solvent not be run of the top of the paper?

Do not allow the solvent front to reach the top of the plate. That may cause erroneous Rf values and may cause spots that are close together to run into each other.

Why is the starting line 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.

What is solvent front?

In chromatography, the solvent front is the position on the TLC plate indicating the furthest distance traveled by the developing solvent (or eluent)

What is solvent front in chromatography?

Why is it necessary to cover the developing chamber tightly during the development of the 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 starting line be above the solvent level?

What would happen if the solvent level in the developing chamber is above the applied spots?

The development method needs to be changed. There is no compound in the sample due to experimental failure. If the level of the solvent system in the chamber is above the spot when the plate is inserted, the compound from the spot will dissolve in the solvent instead of migrating up the plate.

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 must the start line be above the solvent level?

In paper chromatography, why must the start line be above the solvent level? The start line above the solvent level allows the solvent to move past the start line, carrying the dissolved samples along with it.

Why must the eluent be above the starting line in chromatography?

If the eluent is above the 1.5cm line in a chromatography experiment there will not be a proper distribution in a test tube to discover the sources of ink on a paper. A chromatography experiment tests for the sources of ink whether it be chemical or plant based. Why must the spot of the solution on the starting line of the chromatopgraphy be small?

Why must food dye place on starting line above the solvent?

Why must food dye place on starting line above the solvent in chromatography experiment? Having solvent levels below the origin give a more accurate spread of colours, as the water is allowed to begin properly soaking and ink is not lost in the solution upon direct contact.

How does paper chromatography separate molecules?

Paper chromatography separates molecules based on their solubility in the liquid solvent. One end of the chromatography paper is dipped into a solvent reservoir which travels up the paper via capillary action. The samples are placed on the bottom of the paper, above the initial solvent line.