3 IEC

Question 1

Function of ion exchange chromatography? Principle behind it

Answer 1

Partition of compounds between a stationary and a mobile phase

Separation based on charge density

Question 2

Phases in chromatography. E.g. Ion exchange and paper chrom

Answer 2

IEC
Stationary: Resin
Mobile: Buffer

Paper Chromatography
Stationary: Cellulose Paper
Mobile: Solvent (alcohol)

Question 3

Classification of Ion Exchange Resins

Answer 3

Cation Exchanger
Strongly acidic exchanger
>e.g. sulphonic acid groups

Weakly acidic exchanger
>e.g. carboxylic groups

Anionic Exchanger
Strongly basic exchanger
E.g. Quaternary amine groups

Weakly basic exchanger
>e.g. Poly alkyl amine groups

Question 4

Different ion exchanger resins based on:

1. Type
2. Functional group
3. Charge of functional group
4. Sequence of pH buffer
5. Sequence of AA eluted

Answer 4

1. Cation Exchanger

1. Anion Exchanger

Question 5

Is Dowex 50-X4 cation or anion?

Answer 5

Cation

Question 6

Principle of Paper Chromatography?

Answer 6

The more soluble component, the faster it will dissolve in the solvent

Carried along faster by solvent and travel ahead of the others

“Like dissolves like”

Question 7

Factors affecting Rf value?

Answer 7

• Temperature
• Purity & Type of solvent/s used
• Paper quality, adsorbents, & impurities present in adsorbent
• Chamber saturation techniques, method of drying, & devt
• Distance travelled by solute & solvent
• Chem rxn between substances being partitioned
• Size/mol weight of molecule

Question 8

Sources of error?

Answer 8

1. Error during spot application
   - too conc/min volume
   - not same diameter
2. Development
   - Chamber saturation time
   - Improper placement of paper in tank
3. Detection
   - spraying methods affect final result (ninhydrin test)
   - Time of Rf measurement