Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
9 Cards in this Set
- Front
- Back
|
What is eluates/elutants
|
The solutes to be separated
|
|
|
What is eluents
|
The solvents
|
|
|
General rule for size of columns (column chromatography)
|
25~30 times (by mass) the amount of material to be separated
|
|
|
The constant equilibration
|
Different compounds will move down the coloumn at differing rates, depending on their relative affinity for the absorbent on one hand and for the solvent on the other
|
|
|
How does TLC work
|
A thin layer of the absorbent is spread onto the plate
More polar the solution, slower it will ascend due to the dipole-dipole (polar-polar) interaction (capillary action) As in column chromatography, the least polar substances advance faster than the most polar substances |
|
|
For TLC why do we use methelene chloride/hexane for the solvent
|
Because it has intermediate polarity
If too polar, all bands will move fast If not polar enough, bands will not move |
|
|
Rf value equals to
|
distance traveled by substance
________________________________ distance traveled by solvent front |
|
|
Elution sequence
|
|
|
|
How can you check the purity of the compounds?
|
By looking at TLC plate
One spot - no impurities, PURE Several spots - impurities, IMPURE |
