Why is it necessary to run a TLC experiment in a closed container saturated with the solvent?

Why is it necessary to run a TLC experiment in a closed container saturated with the solvent?

It is necessary to run TLC in a closed container and have the interior saturated with the solvent vapor to ensure maximum resolution between components and to prevent solvent evaporating off. If the solvent evaporates off, the Rf value would be lower than the expected value.

How do you saturate a TLC chamber?

Chamber saturation method Fill the chamber with solvent to a height of 0.5 to 1 cm. Carefully tilt the chamber to moisten the filter paper and equilibrate the chamber with solvent vapors. After a few minutes, the chamber is saturated with vapors.

What is the purpose of the moistened folded piece of filter paper inside the chamber Why is this paper important?

What was the purpose of placing a piece of filter paper in the developing chamber? The filter paper allows for the atmosphere inside the chamber to remain saturated and moist. Why did you cover the TLC chamber with a watch glass? To keep the atmosphere saturated and to allow for evaporation.

What happens if too much solvent is used in TLC?

There is no compound in the sample due to experimental failure. The level of the solvent system is too high. 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.

What is the purpose of exposing the developed TLC plate to a saturated iodine vapor?

Iodine Staining. The iodine staining technique allows us to carry around a marked version of our TLC run rather than having to pencil sketch our spots in the UV viewer. The iodine vapors chemically attach to analytes on the TLC plate.

Why are TLC plates developed in a solvent tank?

The purpose of the paper is to saturate the air in the beaker with the solvent vapours. If the air is not saturated with solvent, the solvent that is rising up the plate will evaporate in an attempt to saturate the air. This will lead to high Rf values and poor resolution.

Why is saturation necessary in chromatography?

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 necessary to equilibrate the developing chamber before chromatography?

At all time there is an equilibrium state between all 3 of them. if you do not equilibrate your tank prior to developing the plate then this equilibrium will take place during development itself. this will strongly effect the development. first you will get reproducibility issues.

Why is it necessary to have the TLC chamber covered?

This has to do with the vapor pressure of the solvent. If there’s no cap, the pressure of the TLC chamber is too low and it won’t travel up the TLC plate. So always use a lid. It doesn’t have to be air-tight; simply putting a watch glass over a 50 or 100 mL beaker will do just fine.

Why is UV light used in TLC?

Ultraviolet light is often the first visualization technique attempted on an eluted TLC plate because it is nondestructive and rather simple to carry out. If a dark spot is seen with a UV lamp, it is customary to circle the spot with pencil (as in Figure 2.46b), as the spot will be invisible when the lamp is removed.

How does TLC determine purity?

TLC co-spotting of a second plate allows for preliminary identification of your compound. Thin Layer Chromatography (TLC) is a separation technique requiring very little sample. It is primarily used to determine the purity of a compound. A pure solid will show only one spot on a developed TLC plate.

Why is TLC important?

Thin-layer chromatography (TLC) is a very commonly used technique in synthetic chemistry for identifying compounds, determining their purity and following the progress of a reaction. It also permits the optimization of the solvent system for a given separation problem.

What are the components of a TLC tank?

The developing tank for a TLC should consist of a beaker/jar with a lid a clean, dry beaker Filter paper should be used saturate the beaker atmosphere with solvent vapour watch-glass cover The TLC plate consists of a thin layer of silica gel on an aluminium foil backing.

How does a TLC plate work?

As the solvent travels up the plate, over the spot, an equilibrium is set up, as development solvent competes with the TLC plate for the solute. The silica gel binds to the solute and the development solvent tries to dissolve it away, carrying the solute(s) along as the solvent travels up the plate.

What is the use of TLC in chemistry?

TLC can be used to help determine the number of components in a mixture, the identity of compounds, and the purity of a compound. By observing the appearance of a product or the disappearance of a reactant, it can also be used to monitor the progress of a reaction.

How do I choose the right solvent for TLC?

To choose the right solvent, start with pure solvents of medium elution strength. Perform spot tests to compare different solvent systems. Single solvents are seldom used in TLC; most solvent systems contain several components, but keep it as simple as possible. The solvent system must be capable of wetting the TLC layer.