Thin-Layer Chromatography Exam Questions and Answers 100% Pass

Thin-Layer Chromatography Exam
Questions and Answers 100% Pass


What level should the solvent be in the developing chamber? -

[ANSWER]: Solvent must be below the spotting line so that solvent

does not dissolve samples on the spotting line.




QUESTION: Why is it suggested that one uses tweezers to place the

TLC plate in the developing chamber? -

[ANSWER]: Oils from you fingers can sometimes smear or ruin a TLC

plate.




QUESTION: Why must the bottom of the TLC plate be level with the

bottom of the developing chamber? -

[ANSWER]: If not, then solvent will rise up unevenly on the TLC plate.

,QUESTION: What effect might moving or jostling the developing

chamber during the developing stage have on the rising of the solvent? -

[ANSWER]:




QUESTION: Why must the developing chamber be covered? -

[ANSWER]: Make sure the top is placed back on so the solvent does

not evaporate.




Evaporation of the solvent during this stage causes the development of

the TLC plates to be messy and ineffective.




QUESTION: Before developing a new TLC plate, why do you need to

add solvent to 4mm height? -

[ANSWER]: Ensure you have enough solvent for complete

development, so that solvent reaches determined solvent front.

, QUESTION: Why do you have to make sure solvent does not rise up

past solvent front (5mm)? -

[ANSWER]: If it does, spots in visualization stage will be difficult to

evaluate. Rf will be too high.




QUESTION: Why do you need a filter paper in the developing

chamber? -

[ANSWER]: To saturate developing chamber with solvent vapors,

facilitates capillary action.




QUESTION: Why must you avoid leaning plate against filter paper? -

[ANSWER]: Eluent on the filter paper can be absorbed by adsorbent

and interfere with ascending eluent.




QUESTION: Where should the solvent come from? -

[ANSWER]: The bottom, not the sides. This extra eluent may prevent

the compounds traveling from moving up the plate in a straight line.