Ion-exclusion chromatography is a technique that separates ionic compounds from non-ionic compounds and separates mixtures of acids. It functions using a Donnan exclusion mechanism with an ion exchange resin stationary phase and a liquid mobile phase. Ionic substances pass through the column quickly while non-ionic or partially ionized substances are retained longer. The technique has applications in determining neutral molecules, strong inorganic acids, carboxylic acids, and weakly ionized inorganic acids and bases from samples like wastewater. Conductivity and UV-visible detectors can be used and columns are typically glass, stainless steel, or polymer.

1. CHROMATOGRAPHY- ION-EXCLUSION CHROMATOGRAPHY
Department of Pharmaceutical Sciences Rashtrasant
Tukadoji Maharaj Nagpur University, Nagpur - 440033
Presented by-
Tahmina P. Y. Khan
M.Pharm. 1ST Year (Pharmaceutical Chemistry)
Semester-II 1

2. Content
• Introduction
• Principle
• Instrumentation
• Application
• References
2

3. Introduction
• First introduced by Wheaton and Bauman in 1953.
• ION-EXCLUSION CHROMATOGRAPHY is a technique used to
separate ionic compounds from non-ionic compounds and to separate
mixtures of acids.
• Useful technique for the separation of ionic and nonionic substances.
• It involves the use of strong anion- or cation- exchange resins for the
separation of ionic solutes from weakly ionized or neutral solutes.
3

4. Principle
• Ionic substances pass quickly through the column. Non-ionic
(molecular) or partially ionized substances are held up and are eluted
more slowly. Functions by Donnan exclusion mechanism.
• Mobile phase- liquid (water or aqueous acid or base)
• Stationary phase- ion exchange resins;
a) Cationic
b) Anionic
4

5. • Chromatographic system consists of 3 phases.
5
3-phases
Mobile phase Resin phase
Occluded
liquid phase
Resin phase
Cationic ion
exchanger
resin
a)Anionic ion
exchanger
resin

6. Schematic Illustration Of Ion Exclusion-
6

7. • Thus, analytes are separated by:
i. Exclusion or repulsion if they are ionized and have the same charge as the resin.
ii. Adsorption if they are non-polar or partially ionized.
7

8. Instrumentation
I. Stationary Phase
8
1.Column
Glass ,
stainless Steel
Or Polymer
Length: Diameter Ratio
20:100 to 100:1
Packing The
Column
Wet packing
method

9. II. Application of the sample-
• After packing sample is added to the top of the column, use syringe or pipette.
III. Mobile phase-
• Acid, alkali, buffers
Iv. Elution-
• Components of mixture separated & move down the column at different rates
depending upon the affinity of the ion for ion exchanger.
V. Analysis of the eluate-
• Spectrophotometric
• Conductivity.
9

10. Schematic Illustration Of Instrumentation ION-EXCLUSION CHROMATOGRAPHY
10

11. ELUENTS:
3 types of eluents are used in ion exclusion chromatography-
1. Water eluent
2. Acid eluent - dilute solutions of strong mineral acids ,or dilute solutions of
strong bases.
3. Complexing eluent-An example of this approach is the use of a mannitol
eluent for the determination of boric acid, in which the mannitol serves to
complex the boric acid to form a species which is more easily detectable
by conductivity measurements than is boric acid alone).
11

12. DEGASSING UNIT
ANALYTICAL COLUMN-
• The analytical column consists of stationary phase (wet packing)
• The column packing consists of a reactive layer bonded to inert polymeric
particles.
SUPPRESSOR-
• Suppression plays a key role in the analysis of anions and organic acids using ion
chromatography and conductivity detection.
• For anion analysis, the suppressor is a high-capacity cation exchange membrane or
resin in the acid form. It removes cations from the eluent and replaces them with
H+.
12

13. Detector: -
1. Conductivity Detector: -
In principle, the conductivity detector can be used for some non-aqueous eluents. The
sensitivity of these detectors depends on the temperature during the separation and
detection the temperature must be kept strictly constant.
13

14. 2. Fluorescent based Detectors
3. Detectors with UV- Visible spectrophotometry
14

15. Application
1. Determination of neutral molecules: - Neutral compounds such as sugars
and alcohols can be separated by IEC,
2. Determination of strong inorganic acids: - Sulphate, nitrate and chloride
ions, and strong base cations such as sodium, ammonium, potassium.
Magnesium and calcium ions commonly found in acid rainwater.
3. Separation of carboxylic acids: - The separation of carboxylic acids is the
most common application of ion-exclusion chromatography.
15

16. 4. Determination of Weak inorganic acids and bases: - IEC has found increasing
use for the determination of weakly ionized inorganic anions such as fluoride,
nitrite, phosphate and cyanide.
This approach is very effective for the determination of weakly ionized anions in
samples containing a high concentration of ionic species, e.g., seawater and
wastewaters.
5. Determination of water in some organic solvents.
6. Determination of amino acids and its derivatives.
16

17. References
• M. Mori, K. Tanaka, Q. Xu, M. Ikedu, H. Taoda, W. Hu, "Highly sensitive
determination of hydrazine ion by ion-exclusion chromatography with ion-
exchange enhancement of conductivity detection." Journal of Chromatography A
1039, no. 1-2 (2004): 135-139.
• B. K. Glód, "Ion exclusion chromatography: parameters influencing retention."
Neurochemical research 22 (1997), page no: 1237-1248
17

18. THANK YOU.
18