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ion exchange chromatography

This document provides an overview of ion exchange chromatography. It describes the basic principles of how ion exchange chromatography separates ions and polar molecules based on their charge. The document outlines the different types of ion exchangers used as stationary phases in cation exchange chromatography and anion exchange chromatography. It also discusses several factors that can affect the separation process and provides some examples of applications for ion exchange chromatography.

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P SE E B RE NT ND Y: K AM I .SH IL 1702-13-886-005 GUIDE B Dr.H D Y: RIDAY B RA E 1
W hat Is Ion E xchange Chromatography? P rinciple Ion E xchangers P rocedure F actors Affecting Ion E xchange Chromatography Advantages & Disadvantages Applications References 2
Ion-exchange chromatography (or ion chromatography) is a process that allows the separation of ions and polar molecules based on their charge. Ion exchange chromatography is coined by SM L ST VE AL , E NS, B AUM ANN. It can be used for almost any kind of charged molecule including large proteins, small nucleotides and amino acids. 3
Ion-E xchange chromatography retains analyte molecules on the column based on coulombic (ionic) interactions. T stationary phase surface displays ionic functional he groups (R-X) that interact with analyte ions of opposite charge. T type of chromatography is further subdivided his into: Cation exchange chromatography Anion exchange chromatography T ionic compound consisting of the cationic species he M and the anionic species B can be retained by the + 4 stationary phase.
Cation exchange chromatography retains positively charged cations because the stationary phase displays a negatively charged functional group Anion exchange chromatography retains anions using positively charged functional group 5
Resins Gels Inorganic exchanger 6
Resins are amorphous particles of organic materials Ion exchange resins are used for the separation of small molecules. Strongly acidic cation exchanger -sulphonic acid groups attached to styrene and di vinyl benzene copolymer. W eakly acidic cation exchanger-carboxylic acid groups attached to acrylic and divinyl benzene co-polymer Strongly basic anion exchanger-quaternary ammonium groups attached to styrene and divinyl benzene co-polymer W eakly basic anion exchanger-poly alkyl amine groups attached to styrene and divinyl benzene co-polymer 7
Cellulose and dextran ion exchangers , which are polymers of the sugar glucose , posses larger pore sizes and lower charge densities. B ecause they are much softer than polystyrene resins , dextran and its relatives are called gels . 8
Column : glass, stainless steel or polymers L ength: diameter ratio 20:100 to 100:1 Packing the column : W packing method et Application of the sample : After packing, sample is added to the top of the column, use syringe or pipette M obile phase : Acids, alkalis, buffers… E lution : Components of mixture separate & move down the column at different rates depending upon the affinity of the ion for ion exchanger. T elutes are collected at different stages he Analysis of the elute : spectrophotometric, flame photometry 9
A sample is introduced, either manually or with an autosampler, into a sample loop of known volume. T mobile phase (buffered aqueous solution) carries the he sample from the loop onto a column that contains some form of stationary phase material. Stationary phase material is a resin or gel matrix consisting of agarose or cellulose beads with covalently bonded charged functional groups. T target analytes (anions or cations) are retained on the he stationary phase but can be eluted by increasing the concentration of a similarly charged species that will displace the analyte ions from the stationary phase. 10
F example, in cation exchange chromatography, or the positively charged analyte could be displaced by the addition of positively charged sodium ions. T analytes of interest must then be detected he by some means, typically by conductivity or UV/ Visible light absorbance. A chromatography data system (CDS) usually needed to control an IC. is 11
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• • • • 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 Nature of exchanging ions valency of ions Size of ions P olarizability Concentration of solution 13
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Ion exchange chromatography is used to convert one salt to other. E we can prepare tetra propyl ammonium hydroxide from a g; tetra propyl salt of some other anion. Ion exchange is used to prepare de-ionized water Separation of similar ions A mixture of sodium, hydrogen and potassium can be separated using cation exchanger resin. A mixture of Chloride, bromide, and iodide can be separated using basic anion exchange resin. M T OD: M EH ixture of chloride, bromide & iodide is passed through basic anion exchanger using 0.5M sodium nitrate as eluant. Chloride will first elute. Raise the conc of Sodium Nitrate, B romide will elute, raise the conc of Sodium Nitrate further, 15
Removal of interfering radicals: P hosphate ion is the interfering with the calcium & barium ions. Phosphate is removed using sulphonic acid cation exchanger. + Calcium & barium ions exchanged with H ions while phosphate ion pass through the column. Softening of hard water: H ardness of water due to cal, mg and other divalent ions. T water is passed through cation exchanger charged his with the sodium ions. Ca & M ions retained in the column while g sodium is exchanged. Complete demineralization of water: Removal of both cations & anions. Step A) H ard water is first passed through an acidic cation + exchanger- Ca, M & Na are exchanged by H ions. g Step B T ) his water is then passed thro a basic anion exchanger – Cl, NO2, SO4- are exchanged by OH ions of the exchanger. Separation of L anthanides- L Y, Ce, Rb etc a, 16
P rinciples of instrumental analysis , skoog , latest edition, pno. 641-647 en.wikipedia.org/ wiki/ Ion_chrom atography www.separations.us.tosohbioscience.com .../ rinciplesofChrom / P at ography https:/www.gelifesciences.com .../ / / litdoc11000421_201310032330 16.pdf www.authorstream .com P / resentation/ shreekanta-1507297-ionexchange 17
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