What happens if spots are too large or too small on the TLC plate?

What happens if spots are too large or too small on the TLC plate?

What will happen if your spot is too large? If the spot is large, then two or more spots of a sample may overlap on the TLC plate, thus causing erroneous conclusions about the separation and/or the sample’s purity or content.

Why do TLC spots have to be small?

Spots are applied to the plate using very thin glass pipettes. The capillary should be thin enough to apply a neat spot, but not so thin as to prevent the uptake of an adequate quantity of analyte.

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

When the plate is inserted in the chamber containing solvent, it must be ensured that the level of the solvent is below the spot. If the solvent level is above the spot, the compounds to be analyzed will dissolve in solvent rather than moving up. Therefore, it will not be possible to develop the plate further.

How will you know if there is too little sample on the TLC plate?

Most samples are not colored and need to be visualized with a UV lamp. Hold a UV lamp over the plate and circle any spots you see. If the TLC plate runs samples which are too concentrated, the spots will be streaked and/or run together.

What does 2 spots on a TLC plate mean?

Ideally, each compound in a mixture will produce a distinct spot so a sample with two compounds will give two different spots, and so on. An important property of any compound, is its Rf-value (retention factor). In simple terms, this value is an indication of how far up a TLC-plate a compound has wandered.

What should you do if you inadvertently spotted your plate too low?

If the plate is too low then you need to carry out that part of the experiment again by drawing a new spot on a new TLC at the standard level. This is to ensure accuracy is upheld and correct observations are recorded.

What would happen if the spots applied were too big?

A spot that’s too dense or too big can cause problems during the separation. 6. 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.

What happens if the spots are made too large concentrated when preparing a TLC plate for Development What if the spots are too small dilute?

What happens if spots are made too large when preparing a TLC plate for development? 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.

What happens if the spots are too big in chromatography?

What can go wrong paper chromatography?

Then discuss why each mistake causes a problem and how to fix it….Let them get it wrong.

Mistake	Problem caused	Solution
Incorrect solvent used	Ink insoluble so chromatography doesn’t occur.	Have pupils use a different solvent, eg ethanol.
Start line drawn in ink	Ink dissolves/runs in solvent.	Use pencil as pencil is insoluble in water.

What would happen if you spot too much of a compound on the TLC plate?

3) What could happen if you spot too much of a compound on the TLC plate? Answer: The spot would show trailing.

Why is it important to spot the TLC plate quickly and lightly?

Spotting the plate Allow the solvent to evaporate and spot at the same place again. This way you will get a concentrated and small spot. Try to avoid spotting too much material, because this will deteriorate the quality of the separation considerably (‘tailing’).