Paper & Thin Layer Chromatography Deck (Exam 2) Flashcards
What is the stationary phase of paper chromatography?
Polar cellulose in paper
What is the mobile phase of paper chromatography?
Less polar organic solvent and water
What are the 4 limitations of paper chromatography?
1) Non-volatile samples only
2) Migration path length limited
3) Qualitative analysis only
4) Time consuming
How do you calculate the R(f) factor?
Take ratio of target analyte distance moved to solvent front distance moved
The Nernst Partition Coefficient (K), or distribution constant K(d), is the ratio between…
[solute in stationary phase] to [solute in mobile phase]
What is the purpose of the Nernst Partition Coefficient?
To govern chromatographic performance.
Where should the mobile phase be positioned in paper chromatography?
Below the stationary phase’s origin
What is the mechanism of action for paper chromatography?
Capillary action forces the mobile phase to move along the paper
How does analyte movement distance correlate to analyte polarity?
Shorter analyte distance = Greater analyte polarity
What is the stationary phase coated with for TLC?
Some polar substance, like silica or alumina, impregnated with fluorescent material
What does TLC’s mobile phase consist of?
Less polar organic solvent/solution of two or more liquids
How is TLC better than PC (HINT: time and money)?
TLC is more cost-effective and only takes a minute with the proper mobile phase
What is the general procedure (3 steps) for TLC (HINT: DDV)?
1) Deposit samples
2) Develop plate
3) Visualize spots
What are the 4 common problems with TLC (HINT: OUSS)?
1) Overly-large spots
2) Uneven solvent front movement
3) Streaking
4) Smeared spots
How is TLC useful in drug analysis?
Detecting drug presence
