thin layer chromatography

Question 1

what are the two phases

Answer 1

stationary and mobile phase

Question 2

how does TLC work

Answer 2

by capillary action.

water molecules hydrogen-bond to surface of the paper to form the stationary phase, forms mobile phase when solvent moves across the surface

Question 3

expain how the mobile and stationary phases work

Answer 3

The TLC plate is coated with silica get , this gel is the Stationary phase

mobile phase solvent percolates up from bottom of the plate via capillary action, carrying the analytes in solution. The analytes will adsorb to hydroxyl groups of silica stationary phase to varyup degree
mobile phase carrying the analyte moves up the plate

Question 4

How do analytes separate

Answer 4

based on adsorption to the stationary phase and solubilitys in mobile phase

Question 5

explain adsorption in terms of polarity

Answer 5

the greater the polarity of the analyte, the more efficiently it will andsorb to the hydroxyl sites on the silica and the SLOWER the analyte will move up the TLC plate

the less polar the analyte, the less efficiently it will adsorb to the hydroxyl sites on the silica and the QUICKER the analyte will move up the TLC plate

Question 6

What is the retention factor (Rf)

Answer 6

distant ravelled by analyte from baseline ÷ distance travelled by solvent

Question 7

Applications of TLC

Answer 7

Examination of chemical reactions for completion
Analysis of drug residues and antibiotics in food and environmental samples
Identification of colors, ingredients, preservatives, and sweetening agents in food and cosmetic products
Quality control and purity testing of pharmaceutical formulations

Question 8

what dictates affinity.

Answer 8

adsorption and Solubility

Question 9

define solubility

Answer 9

How well the analyte dissolves in the mobile phase

Question 10

polarity of stationary phase

Answer 10

very polar

the polar analyte molecules are attracted to the polar stationary phase

Question 11

polarity of mobile phase

Answer 11

non-polar

Non-polar analyte molecules will readily dissolve in the non-polar mobile phase

Question 12

what factors affect separation

Answer 12

Polarity:

Polar compounds interact more with the stationary phase → move slowly.
Non-polar compounds interact more with the solvent → move faster.

Solvent Choice:

A more polar solvent will carry polar compounds further.
A less polar solvent will improve separation of non-polar compounds.