2. Over view
What is ion chromatography?
Why this techniqu is useful?

4. Ion chromatography- definition of terms
Ion exchange-
involves exchange of one type of ion in a compound
for another.
exchange of K+, Ca 2+ and Fe 3+ with Na + in water.
Ion exchange chromatography-
involves sequential exchange and elution of ions
from a column. Retention is based on attraction
between solute ions and charge boundary on the
stationary phase.
Ion chromatography-
same as ion exchange chromatography except that
it includes a provision for removing and detecting
(electrochemically) the ions in the eluting agent.

5. Definitions
Ion Chromatography is a liquid chromatographic technique, with which ionic and strongly polar species can be separated and detected.

6. Ion Chromatography System Configuration
Eluent Reservoir
Pump
Guard Column
Analytical Column
Suppressor Device
Conductivity Cell
Chromatography Workstation
Eluent Delivery
Analytical Separation
Detection
Data Acquisition and Instrument Control
Sample Injection

7. Type of Ion Chromatography
Ion Exchange Chromatography
Ion Exclusion Chromatography
Ion Pair (ion Retardation) Chromatography
Alternative Technique

8. Advantages of Ion Chromatography
Speed
- Complete anion and cation profiles in about 10 minutes
Sensitivity
- Analyses in the lowest ppb-range without pre-concentration Analyses in the lowest ppt-range after pre-concentration Limiting factor: contaminations by ubiquitous ions such as chloride and sodium
Selectivity
- Huge variety of stationary phases Specific detection (suppression, UV, fluorescence, MS, ICP)

9. Advantages of Ion Chromatography (cont.)
Simultaneity
- Simultaneous analysis of many sample components (Contrary: AAS, Photometry, Titration, etc.) Limiting factor: extreme concentration differences between the sample components (Example: Semiconductor grade chemicals)
Costs
- Contract laboratories offer anion and cation profiles with IC for US$ Price drop with system hardware as in all hightech areas
Robustness
- pH and solvent compatible separators allow a variety of applications - Analysis of complex matrices such as waste water, foods, body fluids, etc.

10. History Aristol experiment(384-322 B.C) Philasopheres(1561-1626)
Natural Zeolites in soil(1850)
Teoritical research(1876)
First commerical purposes(1896)
First synthetic compound(1903)
First truly successful use(1905)
Synthesise of organic compound(1935)
Use of small particles(1946)

11. Advantages of organic polymer
High capasity
Low sensitivity to temperature and PH
Provided a back bone for various tyoe
of exchange groups

12. Making a cation Exchange Resin

13. Ion exchangers Three main classes Resins
(polystyrene resins; used for molecules with Mr <500)
Gels
(cellulose and dextran; used for large molecules
like proteins and nucleic acids)
Inorganic exchangers
(hydrous oxides of Zr,Ti,Sn and W; used for separations
under harsh conditions (high temperature, high radiation
levels, strongly basic solutions and powerful oxidizing
agents)

14. Resin beads

15. Exchange functional groups
Cation Exchangers Anion Exchangers
strong SO3H N(CH3)3,Cl
-COOH N(CH3)2CH2OH,Cl
-CH2 SO3H
-OH NR2H,Cl
-SH NRH2,Cl
weak HPO2 H NH3,Cl

16. A Lable of a Resin
Sulfonic acid,Na
Mesh:20-50 8X
4.4 meq/g +

17. Lable information Cross-linking Porosity Moisture holding capasity
2X High
4X IM.High
8X Medium
12X IM.Low
16X Low

18. Structure of Sodalite

19. Different types of ion exchange resins
Polymeric porous particles
(formed from co-polymerisation of styrene-divinylbenzene)
Pellicular and superficially porous particles
(formed by coating the ion exchange resin on to an
impervious inert core)
Totally microporous particles with bonded phases

22. Classification of ion exchangers
Classified :
by the charge on the stationary phase as:
anion exchangers-contains positively charged groups
cation exchangers-contains negatively charged groups
as strongly or weakly acidic or basic:
strongly acidic cation exchangers eg RSO3-
weakly acidic cation exchangers e.g RCO2-
strongly basic anion exchangers e.g RNR’3+
weakly basic anion exchangers e.g RNR2’H+

23. Example:

24. Selectivity and retention in ion exchange analysis
These are affected by the size and charge of the solvated sample ion.
Ion exchangers bind strongly to ions with higher charges, lower hydrated radii and higher polarizability
Thus order of selectivity is generally:
Pu 4+ >> La 3+ > Ce 3+ > Pr 3+ > Eu 3+ > Y 3+ > Sc 3+ > Al 3+ >> Ba 2+ > Pb 2+ > Sr 2+ > Ca 2+ > Ni 2 + > Cd 2 + > Cu 2+ > Co 2+ > Zn 2+ > Mg 2+ > UO2 2+ >> Ti + > Ag + > Rb + > K + > NH4 + > Na + > H + > Li +

25. Retention Determining Parameters (II)10 20 30
Minutes 4 µS F-
Cl-
NO2-
Br-
NO3-
PO43-
SO42- I-
SCN-
S2O32- 2 6
Monovalent Anions
Multivalent Anions
An exception to the rule?

26. Retention Determining Parameters (III)10 20 30
Minutes 4 µS F-
Cl-
NO2-
Br-
NO3-
PO43-
SO42- I-
SCN-
S2O32- S O 2-

27. Selectivity and retention in ion exchange analysis
The pH of the mobile phase
The total concentration and type of ionic species in the mobile phase
Addition of organic solvents to the eluant
The column temperature

29. PH of the mobile phase

30. Concentration

31. Ion Exchange Kinetics There are 5 main steps: 1)agiated
2)passage from the outer solution to the bead
3)actual exchange
4)migration
5)exit to the mobile phase

32. Donnan equilibrium [K+]i [Cl-]i = [K+]o[Cl-]o --------(1)
Refers to the equilibrium between ions in solution and ions inside the resin. This is the basis of ion-exclusion chromatography.
For an anion-exchange resin, R+, in its Cl- form, immersed in a solution of KCl:
[K+]i [Cl-]i = [K+]o[Cl-]o (1)
where i and o denote inside and outside the resin respectively.
Inside the resin,
[R+]i + [K+]i = [Cl-]i (2)
Since from charge balance :
[K+]o = [Cl-]o
considerations, equation (1) becomes :
[K+]i([R+]i + [K+]i ) =[K+]o (3)
Thus
[K+]o > [K+]i

33. Porous particlate and Micro porous membrane

34. FASTCHROM standard module and end plates

35. Applications of Ion exchange
In water purification.
Deionised water is made by passing water through a anion-exchange in it OH- form and a cation-exchange resin in its H+ form.
Thus Cu(NO3)2 can be removed from water by the following reactions
Cu 2+ H+ ion exchange 2H+ H2O
2NO3- OH- ion exchange 2OH-}
In water softeners
Cation exchange is used to remove Ca 2+ and Mg 2+ from hard water
In converting one salt to another.
In pre-concentrating trace components of a mixture
Cation-exchange resins are used to concentrate trace metals..

36. Ion chromatography This is the high performance version of IEC.
Common examples are:
Suppressed cation chromatography and
Suppressed anion chromatography
The key feature of IC is the presence of
an anion or cation separator column
a membrane ion suppressor
a detector
The separator column separates the solutes while the suppressor replaces unwanted ions in the eluent with nonionic species

37. The Instrument
COST: $40,000

38. Operation Principles Eluent from the gradient pump enters the rheodyne
injection valve port inside the enclosure
From the injection valve, eluent and sample flow through
the guard column, the analytical column, the suppressor
and finally through the detector cell.

39. The IC Schematic Pump, Column ($800), Guard ($200)
Air Pump for sample injection

40. Schematic of a Loop Injector1 2 3 4 5 6 8 7
Eluent
Waste
Separator
Sample
Injection valve
Sample loop

41. Ion Chrom. for analysis of rain
If inject sample with nitrate ion, nitrate replaced bicarbonate, but more bicarbonate moves in and kicks off nitrate
Process continues as moves through column (ions go on and off beads)
Sulfate in sample as well. Harder for bicarbonate to knock off.
Conclude: Nitrate exits before Sulfate

42. Ion Chrom.
See Peaks (Rain has nitrate, sulfate, some chloride)

43. IC Report

49. What are Suppressors in Ion Chromatography Good For ?
To reduce background conductance caused by the eluent and, therefore, to reduce noise
To convert analyte ions into a more strongly conducting form
To improve sensitivity
To improve the dynamic range
To be able to use high capacity separators with higher ionic strength eluents
To be able to use gradient elution techniques in combination with conductivity detection

50. Advantages of Continuous Suppression
Improved stability of the system
Very little drift and low noise
High suppression capacity
No external regeneremts necessary
Simple operation – no extra programming
Simplified hardware – no extra valves
Flexible method development

57. Single ion chromatography
Used when
Exchange capacity of the separator column is low
Dilute eluents are employed
Ion suppression is unnecessary
Examples of resins with low exchange capacities are:
Na + or K + salts of benzoic, p-hydroxybenzoate and phthalate.

58. Gradient elution
Ionic gradient elution is similar to temperature or solvent gradient.
Changing the ionic strength or pH of the eluent improves separation considerably.
For example, a mixture of Na+, Li+, Ca 2+ and Fe 3+ can be separated by using elution with increasing concentrations of HCl.
The order of elution being Li +, Na + > Ca 2+ > Fe 3+

59. Gradiant separation of a synthetic mixture of 36 anions in 24 min.

61. Gradiant Elution

62. Detector in Chromatography
Electrochemical Detector Conductivity Detector Amperometric Detector Pulsed Amperometric Detector
Spectroscopy Detector UV/Vis Fluorescence PDA

63. Detection Conductivity detectors are the most popular
In addition, when analytes have
Ultraviolet absorbance
Fluorescence or
Radioactivity other forms of detection are employed.
Many ion exchange methods require the presence of complexing agents (EDTA, citrate) and various electrolytes to achieve good resolution. Therefore, conductivity detectors can not be used without modifying the process (eg by suppressing some of the ions).
Indirect detection is possible when benzoate or phthalate eluents are used.

64. The Altec model 1000 electrochemical regenerated ion suppression system and Sample preconcentrator

65. IC conductivity Detectors
Detectors: Based on ability of water to conduct electricity
Suppressor membrane destroys bicarbonate only
Conductivity of ions can be measured to very low levels

66. Electrochemical palsed amperometric cell assembly

68. Vydac 250x4.6 2-6 100 20 spherical silica with IC bonded quaternary
Column size PH range capasity Particle size Type of packing
mm µm
Vydac x spherical silica with
IC bonded quaternary
groups
INtraction 50x Neutral hydrophilic Ion100
narymacroporous
resin with covalentlyi bond
ammonium groups
Hamilton x Highly crosslinked
-X covalentlyi bond
Bio-GelTSX 50x Polymetacrilat gel coated
with
Anion PW quaternaryammonium
Waters ic X Same
Pak A

69. One chromatogram with 5 detector

70. Ion-pair chromatography
Uses reverse phase HPLC in place of an ion exchange column
A hydrophobic ion pairing reagent containing a counter-ion, with an opposite charge to the ion to be determined is added to the mobile phase.
This counter ion combines with the ions of the eluent to form ion pairs in the stationary phase.
For example, Fe(phen) forms [Fe(phen)3 2+ ] [anion] ion pair.
Retention of analytes depend on
Alkyl chain length of the counter-ion
Concentration of the ion pairing reagent
Solvent strength
Combination with ion suppressor

76. Example for separation with regeneration

78. …THE …END…