Chemistry
Ion Exchange Chromatography
Ion exchange chromatography is a separation technique based on the reversible exchange of ions between a stationary phase and the ions in a sample. The stationary phase is typically a resin with charged functional groups that attract and retain ions of opposite charge. By applying a gradient of salt concentration, the bound ions are eluted in order of increasing strength of interaction with the resin.
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11 Key excerpts on "Ion Exchange Chromatography"
eBook - PDF- Ayben Kilislio?lu, Ayben Kilislioğlu, Ayben Kilislioğlu(Authors)
- 2012(Publication Date)
- IntechOpen(Publisher)
Section 4 Ion Exchange Chromatography Chapter 14 © 2012 Khan, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Role of Ion Exchange Chromatography in Purification and Characterization of Molecules Hidayat Ullah Khan Additional information is available at the end of the chapter http://dx.doi.org/10.5772/52537 1. Introduction Adsorption chromatography depends upon interactions of different types between solute molecules and ligands immobilized on a chromatography matrix. The first type of interaction to be successfully employed for the separation of macromolecules was that between charged solute molecules and oppositely charged moieties covalently linked to a chromatography matrix. The technique of Ion Exchange Chromatography is based on this interaction. Ion exchange is probably the most frequently used chromatographic technique for the separation and purification of proteins, polypeptides, nucleic acids, polynucleotides, and other charged biomoleules (1) . The reasons for the success of ion exchange are its widespread applicability, its high resolving power, its high capacity, and the simplicity and controllability of the method. 2. The theory of ion exchange Purification using Ion Exchange Chromatography depends upon the reversible adsorption of charged solute molecules to immobilized ion exchange groups of opposite charge. Most ion exchange experiments are performed in five main stages. These steps are illustrated schematically. The first stage is equilibration in which the ion exchanger is brought to a starting state, in terms of pH and ionic strength, which allows the binding of the desired solute molecules.
eBook - PDF- Dean F. Martin, Barbara B. Martin, Dean F. Martin, Barbara B. Martin(Authors)
- 2013(Publication Date)
- IntechOpen(Publisher)
Through its continuous growth, chromatography became the most widely used analytical separation technique in chemistry and biochemistry. Thus, it is not exaggeration to call it the technique of the 20th Century. Figure 1. Schematic diagram of the principles of chromatography as discovered by Tswett (1901). Column Chromatography 2 2. Ion chromatography Classical liquid chromatography based on adsorption- desorption was essentially a non-linear process where the time of retardation (retention time) and the quantitative response depend on the position on the adsorption isotherm. Essentially, it was a preparative technique: the aim was to obtain the components present in the sample in pure form which could then be submitted to further chemical or physical manipulations [3]. Ion Exchange Chromatography (or ion chromatography, IC) is a subset of liquid chromatog‐ raphy which is a process that allows the separation of ions and polar molecules based on their charge. Similar to liquid chromatography, ion chromatography utilizes a liquid mobile phase, a separation column and a detector to measure the species eluted from the column. Ion-exchange chromatography can be applied to the determination of ionic solutes, such as inorganic anions, cations, transition metals, and low molecular weight organic acids and bases. It can also be used for almost all kinds of charged molecule including large proteins, small nucleotides and amino acids. The IC technique is frequently used for the identification and quantification of ions in various matrices. 2.1. Ion chromatography process [4] The basic process of chromatography using ion exchange can be represented in 5 steps (as‐ suming a sample contains two analytes A & B): eluent loading, sample injection, separation of sample, elution of analyte A, and elution of analyte B, shown and explained below. Elu‐ tion is the process where the compound of interest is moved through the column.
eBook - PDFChemical Analysis
Modern Instrumentation Methods and Techniques
- Francis Rouessac, Annick Rouessac, John Towey(Authors)
- 2022(Publication Date)
- Wiley(Publisher)
Chemical Analysis: Modern Instrumentation Methods and Techniques , Third Edition. Francis Rouessac and Annick Rouessac, translated by John Towey. © 2022 John Wiley & Sons Ltd. Published 2022 by John Wiley & Sons Ltd. Companion Website: www.wiley.com/go/Rouessac/Analysis3e Ion Chromatography Chapter 4 I on-exchange chromatography (IEC) is the main technique in ion chromatography (IC), which also includes ion-pair chromatography (IPC) and ion-exclusion chromatography. IEC enables the study of organic compounds as long as they are polar. It shares numerous common features with HPLC, yet can be differentiated by the principle of separation. The mobile phase is composed of an aqueous ionic medium and the stationary phase is a solid that behaves as an ion exchanger. Among the many detection methods available, those based on Chapter 4: Ion Chromatography 118 the conductivity of solutions are preferred. However, the current applications of IC (environmental and biochemistry analyses) are far broader than the analysis of simple cations or anions by which the technique first gained renown. 4.1 BASICS OF ION CHROMATOGRAPHY Ion-exchange chromatography is mostly used for the separation of polar compounds, whether organic or mineral, depending on their charge. Stationary phases are made up of polymers or organic resins or silica gel, on the surface of which ionized functional groups are covalently bound, capable of reversibly exchanging charged species present in the analytes. If a compound has a high charge density, it will be retained a longer time by the stationary phase. This exchange process is much slower when compared with those found in other types of chromatography. IEC instruments have the same modules as those found in HPLC (Figure 4.1), with suitable characteristics to manage the aggressiveness of solutions and acidic or basic mobile phases.
eBook - PDF- Erich Heftmann(Author)
- 1991(Publication Date)
- Elsevier Science(Publisher)
This interaction is often called reversed-phase interaction. Thus, ion-exchange chroma- tography has a very wide field of application, ranging from the simplest inorganic cations and anions to the very large ions of proteins and nucleic acids. Carbohydrates can be separated by ion exchange, as can the optical isomers of amino acids. Ion exchange was first recognized in soils, where it is responsible for the retention of fertilizers and plant nutrients. In industry, the earliest and still the most important use of ion exchange is water conditioning. Hydrometallurgy is another very important application. However, this book is concerned with chromatography. The emphasis of this chapter will be on high-resolution, high-performanceliquid chromatography that uses ion exchange or ion-exchangingmaterials. 5.2 ION EXCHANGERS 5.2.1 General considerations For a solid substance to exchange ions with a solution, it must have ions of its own, and these ions must be able to move freely in and out of the molecular structure. The exchange can occur at the surface, and this is the case with clay minerals and with porous silica, but in general the solid must have an open, permeable structure. It must also carry ionic, electrically charged groups that are anchored to the solid structure. These are called the fixed ions. Balancing the charges of the fixed ions are the mobile ions or exchangeable ions, also called counterions. These are the ions that take part in ion exchange. A229 Ion exchangers can be inorganic or organic. They can have organic structures grafted on to an inorganic core, generally porous silica. An interesting class of inorganic ion exchangers is the artificial zeolites or molecular sieves; their crystal structure has large cavities and channels in which the mobile ions reside. They are very important as cata- lysts and in special separation processes, but they have no applications to chromatography, so we shall not describe them here.
eBook - ePub- (Author)
- 2009(Publication Date)
- Academic Press(Publisher)
Liquid Chromatography: Mechanisms: Ion Chromatography
P.R. Haddad University of Tasmania, Hobart, Tasmania, AustraliaIntroduction
The term ion chromatography (IC) does not refer to a single, specific chromatographic technique, but rather to the specialized application of a collection of established techniques. When introduced in 1975 IC referred only to the separation of inorganic anions and cations using a specific combination of ion exchange columns coupled to a conductimetric detector. Since that time, the definition of IC has expanded greatly and it can be best categorized in terms of the type of analytes separated rather than the manner in which the separation is achieved. We can therefore define IC to be:the use of liquid chromatographic methods for the separation of inorganic anions and cations and low molecular weight water-soluble organic acids and basesWhile a range of chromatographic methods (e.g. reversed-phase ion interaction chromatography) can be used to separate these types of analytes, it is true to say that the majority of IC separations are performed by ion exchange using specialized stationary phases. In the interests of brevity, the discussion of IC will therefore be confined to ion exchange methods only. The interested reader seeking a broader coverage of the technique is referred to any of the standard texts listed in the Further Reading section.IC methods employing ion exchange can be divided somewhat arbitrarily into two main groups, largely on the basis of historical development and commercial marketing influences. These groups of methods are referred to as ‘nonsuppressed ion chromatography’ and ‘suppressed ion chromatography’.Nonsuppressed IC comprises all those methods in which an ion exchange column is used to separate a mixture of ions, with the separated analytes being passed directly to the detector . The hardware configuration employed is shown schematically in Figure 1A
eBook - PDFHPLC
Practical and Industrial Applications, Second Edition
- Joel K. Swadesh(Author)
- 2000(Publication Date)
- CRC Press(Publisher)
Chromatogr. , 637, 63, 1993. 79. Smith, R. E., Yourtee, D., Bean, T., and McQuarrie, R. A., Ion chromatography on a new moderate capacity anion exchange column, J. Chromatogr. Sci., 31, 366, 1993. 80. Amey, M. D. H. and Bridle, D. H., Application and development of ion chro-matography for the analysis of transition metal cations in the primary coolants of light water reactors, J. Chromatogr., 640, 323, 1993. 81. Jensen, D., Weiss, J., Rey, M. A., and Pohl, C. A., Novel weak acid cation-exchange column, J. Chromatogr., 640, 65, 1993. 82. Nair, L. M., Saari-Nordhaus, R., and Anderson, Jr., J. M., Simultaneous sepa-ration of alkali and alkaline-earth cations on polybudaiene-maleic acid-coated stationary phase by mineral acid eluents, J. Chromatogr., 640, 41, 1993. 83. Lee, D. P., A new anion exchange phase for ion chromatography, J. Chromatogr. Sci. , 22, 327, 1984. 84. Xianren, Q., Chong-yu, X., and Baeyens, W., Computer-assisted predictions of resolution, peak height and retention time for the separation of inorganic anions by ion chromatography, J. Chromatogr., 640, 3, 1993. 85. Benson, J. R. and Woo, D. J., Polymeric columns for liquid chromatography, J. Chromatogr. Sci. , 22, 386, 1984. 86. Brenman, L. and Schmuckler, G., Quantitative determination of anions in fertilizers using ion chromatography, LC-GC, 11(4), 298, 1993. 87. Fujiwara, M., Matsushita, T., Kobayashi, T., Yamashoji, Y., and Tanaka, M., Preparation of an anion-exchange resin with quaternary phosphonium chlo-ride and its adsorption behavior for noble metal ions, Anal. Chim. Acta , 274, 293, 1993. 88. Michigami, Y., Kuroda, Y., Ueda, K., and Yamamoto, Y., Determination of urinary fluoride by ion chromatography, Anal. Chim. Acta, 274, 299, 1993. 89. Cassidy, R. M. and Elchuk, S., Dynamic and fixed-site ion-exchange columns with conductimetric detection for the separation of inorganic ions, J.
eBook - PDF- James S. Fritz, Douglas T. Gjerde(Authors)
- 2009(Publication Date)
- Wiley-VCH(Publisher)
The metal ions studied are either retained as a sharp band or quickly pass through the column. Thus, we have an ‘all-or-nothing’ situation, and excellent group separations are obtained. Chromatographic separations of individual ions are also possible, and many have been published. An example is shown in Figure 1.2. Ion exchange in non- aqueous and mixed media has been reviewed [26]. Figure 1.2 Separation of nickel(II) and manganese(II) on a 6.0 × 2.2 cm column containing Dowex 1 × 8 resin, with partly nonaqueous eluents. (From Ref. [25] with permission.) 7 1 Introduction and Overview Systems containing dimethylsulfoxide, methanol and hydrochloric acid have been studied for the anion-exchange behavior of 26 elements [27]. Numerous sep- arations of two- to four-component mixtures of metal ions were carried out with quantitative results. 1.2.4 On-line Detection At this stage in the development of ion-exchange chromatography, separation of cations or anions was still a slow and laborious process. It was becoming apparent that widespread use of ion-exchange chromatography as an analytical tool would require a system that gave fast separations with automatic recording of chromato- grams. In 1971 an apparatus for ‘forced-flow chromatography’ was described in which the eluent was pushed through the analytical column by compressed nitrogen [28]. Detection of eluted ions was by UV-Vis spectrophotometry using a 30 mm × 2 mm flow cell. Iron(III) (10–90 lg) could be separated from most other metal ions and measured quantitatively in only 6 min. Forced-flow methods were soon developed for the chromatographic separation of a number of other metal ions [29–32]. The chromatograph was modified in 1974 so that a complexing reagent such as PAR or Arsenazo could be added to the column effluent via a mixing tee [33]. This made it possible to detect virtually any metal ion that could form a highly-colored complex.
eBook - PDF- Walter G. Berl(Author)
- 2013(Publication Date)
- Academic Press(Publisher)
In the opinion of the authors, the opportunity of performing difficult Chromatographie separations with ion-exchange resins has been overlooked by many analysts. A reason for this neglect may be the difficulty of finding by trial and error the most favorable set of elution conditions for a desired separation. The plate theory of ion-exchange chromatography permits the substitution of mathematical logic for guess work in the selection of the concentration and pH of the eluent, in the decision to add or not to add a complexing agent to the eluent, and in the choice of the length of the column. It is hoped that the rather complete presentation of the plate theory in this volume will encourage its use and extend the usefulness of ion-exchange chromatography. The use of ion-exchange resins in Chromatographie separations that do not involve exchange reactions is a comparatively recent development. Ion exclusion has found industrial rather than analytical applications. On the other hand, the value to chemical analysis of salting-out chromatography and solubilization chromatography has been conclusively demonstrated. Further analytical applications of these techniques are confidently expected. The discovery of ion-retardation resins is a new and very interesting development which has not yet been put to work in the cause of chemical analysis. Quite the reverse situation exists in regard to chelating and redox resins. It is certain that analysts would be quick to apply a really good chelating resin, one that would combine the stability and reaction velocity of the sulfonated cross-linked polystyrenes with high specificity. Likewise, 218 WILLIAM RIEMAN, III AND ROGER SARGENT many applications are waiting for the production of fast-acting, stable redox resins.
eBook - PDF- Danilo Corradini(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
Although the chromatographic peaks are tailing for the presence of pores in the SUDD inducing slow diffusion, this seems a very interesting and promising approach. Permanently or dynamically coated reversed-phase monoliths with ion-exchangers suffer from variations in coating stability and are sensitive to temperature and changes in the composition of the eluent. Monolithic columns with chemically bonded ion-exchange groups could be a valid alterna-tive to overcome these problems. Since at present this kind of stationary phases has been investi-gated but the separation mechanism is more a chelation than an ion exchange, they will be discussed in the appropriate chapter (chelation ion chromatography). 14.2.6 L IGAND -A SSISTED C ATION AND A NION E XCHANGE Since the selectivity coefficients of transition and heavy metal ions (M n + ) for cation exchangers are similar, their separations using conventional ion-chromatographic columns (e.g., sulfonated cation exchangers) were performed with eluents containing one or more weak ligands (e.g., oxalic acid, citric acid, tartaric acid, 2-hydroxyisobutyric acid) that reduce the charge density of metal ions and change their selectivity through the formation of neutral or anionic complexes (MeL) [9]. In addition, the ligand avoids the formation of insoluble or hydroxo-species of metal ion when an acidic eluent is not suitable for separation. In catIon Exchange Chromatography, metal ions, during the time spent in the eluent, are at equilibrium between their ionic free form, are available for the ion-exchange with the stationary phase, and their complex form originates with the ligand. For these separations, the chelating agent type, pH, and ionic strength play a relevant role. The type of ligand [106–108] influences the selectivity of the separation through the different stability constants with the same metal ions, and by modifying the pH, the stability constants of metal complexes are modified.
- Karen M. Gooding, Fred E. Regnier, Karen M. Gooding, Fred E. Regnier(Authors)
- 2002(Publication Date)
- CRC Press(Publisher)
Ion-Exchange Chromatography Fred E. Regnier Purdue University West Lafayette, Indiana Karen M. Gooding Eli Lilly and Company Indianapolis, Indiana tNTRODUCTtON Ion-exchange chromatography has been used inthe separation of ionic species for more than half a century. Early separations were achieved with either sulfonated or quatemized polystyrenedivinylbenzene (PSDVB). Unfortunately, these materi- als are often unsuitable for protein separations because the strong nonspecific adsorption between the hydrophobic sorbents and proteins necessitates the use of organic solvent or extremes in pH to achieve elution. Such conditions are sufficiently harsh to denature protein three-dimensional structure and, con- sequently, alter biological activity. In 1958, Sober and Peterson [1] described the use of diethylaminoethyl (DEAE)-derivatized cellulose in the anton-exchange separation of proteins. This hydrophilic matrix overcame many of the problems of the PSDVB-based materials. Shortly thereafter,carboxymethyl-derivatized cellulose was introduced for the cation-exchange chromatography of proteins. Separations achieved using 81 82 Regnier and Gooding cellulose-based ion-exchange sorbents had high protein recovery, good loading capacity, and outstanding chemical stability in the pH range 2-12. With the addition of dextran and agarose support matrices in the early 1960s, a wide variety of carbohydrate-based ion-exchange materials became available for protein separations. These materials have ptayed a major role in the evolution of both separation science and modern biochemistry because most fully char- acterized proteins have been purified at some stage using ion-exchange chroma- tography. Soft gel materials, which include most carbohydrate matrices, have the primary limitation of poor mechanical strength.This precludes their use at high mobile phase velocity and in small particle diameters, both of which substantially increase the performance of liquid chromatography columns.
eBook - PDF- J. Inczédy, I. Buzás(Authors)
- 2016(Publication Date)
- Pergamon(Publisher)
Determination of the separated compounds is possible photometrically by various colour reactions. The different adsorption power of alcohols makes possible the separ-ation of various alcohols by simple selective sorption. 316 Ι Ο Ν E X C H A N G E R S IN O R G A N I C A N A L Y S I S 8.5.3. Separations on the basis of sizes of ions or molecules An ion-exchange column prepared from a resin of adequate small pore size is suitable for the separation of ions of different size. While ions of large size do not pass into the pores of the resin and therefore in solution they pass through the resin column, ions of small size can be bound. The efficiency of separations of this type depends on (1) The size and form of the ions to be separated. (2) The pore size of the ion exchanger. (3) The surfacial capacity of the resin. (4) The flow rate. The size of ions is fixed, but it can be increased in some cases by complex formation or compound formation. The pore size of the synthetic resin-based ion exchangers can be affected by the degree of cross-hnking, i.e., by changing the divinylbenzene content (see Chap-ter 2). Because synthetic resins, in contrast to the silicate-based ion exchangers, are hetero-capillary, i.e. do not have a uniform pore size, with uniform internal diameter, their selectivity is not too high with respect to separation according to the size. A good separation can be obtained by them only if the difference in size of the ions to be separ-ated is large enough. Because ion-exchange can take place on the sur-face of the resin particles independently of the size of ions, the surface is not selective in respect of ion sizes. The relative extent of surfacial ion-exchange, being disadvantageous in respect of the separation, can be decreased to some extent by increasing the grain size or more efficiently by ''blocking the active groups of the surface.
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