Ion exchange chromatography

Abstract

Ion chromatography (or ion-exchange chromatography) is a chromatography process that separates ions and polar molecules based on their affinity to the ion exchanger. It works on almost any kind of charged molecule including large proteins, small nucleotides, and amino acids

Full text

Presented by
Dr. SK. Abdul Rahaman Ph.D
Principal & Professor
NIRMALA COLLEGE OF PHARMACY
ATMAKUR, MANGALAGIRI, ANDHRA PRADESH, INDIA

INTRODUCTION:
Ion chromatography (or ion-exchange chromatography)is a
chromatography process that separates ions and polar
molecules based on their affinity to the ion exchanger. It works
on almost any kind of charged molecule including large
proteins, small nucleotides, and amino acids
PRINCIPLE:
Adsorption process (Surface phenomenon)
Ion Exchange chromatography is used in the separation of
charged biomolecules. The crude sample containing charged
molecules is used as the liquid phase. When it passes through
the chromatographic column, molecules bind to oppositely
charged sites in the stationary phase.

CLASSIFICATION OF RESINS:
According to the chemical nature they classified as:-
1. Strong cation exchange resin –Sulphonic acid
2. Weak cation exchange resin –Carboxy methy compound
3. Strong anion exchange resin –Quaternary ammonium compound
4. Weak anion exchange resin - Diethyl aminoethyl compound
Cation exchange chromatography retain positively charged cations because the
stationary phase displays a negatively charged functional group:
R-X−C++ M+B−⇄R-X−M++ C++ B−
Anion exchange chromatography retains anions using positively charged functional
group: R-X+A−+ M+B−⇄R-X+B−+ M++ A−

According to the Source they are classified as:
Natural : Cation - Zeolytes, Clay
Anion - Dolomite
Synthetic : Inorganic & Organic resins
Organic resins are polymeric resin matrix
The resin composed of –Polystyrene (sites for
exchangeable functional groups), Divinyl benzene
(Cross linking agent)- it offers stability

Properties of Ion exchange resin:
•It must be chemically stable
•It should be insoluble in common solvents
•It should have a sufficient degree of cross linking
•The swollen resin must be denser than water
•It must contain sufficient no.of ion
exchange groups

a) Pellicular type with ion exchange resins:
•30 - 40µ with 1-2µ film thickness
•Very low exchange capacity
b) Porous resin coated with exchanger beads:
•Size 5 -10µ
•Porous & highly efficient
c) Macroreticular resin bead:
•Not highly efficient & low exchange capacity

It affects swelling & strength & solubility
Swelling:
When resin swells, polymer chain spreads apart
Polar solvents →swelling
Non-polar solvents → contraction
Swelling also affected electrolyte concentration.

Particle size & Porosity
↑surface area & ↓particle size will ↑rate of ion
exchange
Particle size 50-100 mesh / 100-200 mesh
Regeneration
Cation exchange resin are regenerated by
treatment with acid, then washing with water
Anion exchange resin are regenerated by
treatment with NaOH, then washing with water
until neutral

1. Column
•Column is made up with Glass, stainless steel or polymers
Length: diameter ratio 20:100 to 100:1
2. Packing the column
•Wet packing method
3. Application of the sample
After packing, sample is added to the top of the column by
using syringe or pipette

4.Mobile phase
Acids, alkalis, Buffers
5.Elution
Components of mixture separate & move down the column at
different rates depending upon the affinity of the ion for ion
exchanger.
•The elutes are collected at different stages
6. Analysis of the elute
•The eluted compound is measured by using
spectrophotometry, flame photometry,
polarography and conductometry.

a. Nature & properties of ion exchange resins
Cross linking & swelling is important
If more cross linking , they are more rigid, but swelling is
less
swells less → separation of ions of different sizes is
difficult
b. Nature of exchanging ions
1. Valency of ions 2.Size of ions
3.Polarizability 4.Con. of solution
5. Concentration & charge of ions

APPLICATIONS
Softening of water
Demineralization of water
Purification of solutions free from ionic impurities
Separation of inorganic ions
Separation of sugars, amino acids
To separate creatine kinase (CK) isoenzymes from human
serum and tissue sourced in autopsy material (mostly CK
rich tissues were used such as cardiac muscle and brain)
Ion Exchange Chromatography is used in different aspects of
product development and quality control testing. For
example, IC is used to improve stabilities and solubility
properties of pharmaceutical active drugs molecules as well
as used to detect systems that have higher tolerance for
organic solvents.

FILL IN THE BLANKS
1. Hard water is converted into Soft water by _________ chromatography
2. Strong cationic exchange resin is _____________
3. Particle size of resins are increases then rate of ion exchange will be _______
4. The principle involved in Ion Exchange chromatography is ____________
5. The cross linking of ion exchange resin is increases; swelling is _________
and exchange of ions will be __________
KEY:
1. Ion Exchange chromatography
2. Quaternary ammonium compound
3. Increases
4. Adsorption
5. less & less