Ion exchange chromatography By Mennatallah Abdelshaheed

IEC, is a subdivision of liquid-solid chromatography. Stationary phase : Resin or gel Mobile phase : contains the inorganic salt dissolved in a suitable solvent, is applied to the column. Ion exchange chromatography

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

The separation occurs by reversible exchange of ions between the ions present in the solution ( mobile phase ) and those present in the ion exchanger ( stationary phase) We can say it is an adsorption phenomenon. The adsorption is electrostatic.

Principle: Ion Exchange chromatography principle, Exchange of ions is the basic principle in this type of Chromatography. In this process two types of exchangers i.e., cationic and anionic exchangers can be used. Cationic exchangers possess negatively charged group, and these will attract positively charged cations. These exchangers are also called “Acidic ion exchange” materials, because their negative charges result from the ionization of acidic group. Anionic exchangers have positively charged groups that will attract negatively charged anions. These are also called “Basic ion exchange” materials.

Applications of Ion Exchange Chromatography: It is extremely used in the analysis of amino acids. The amino acid “Autoanalyzer” is based on in exchange principle. To determine the base composition of nucleic acids. Chargaff used this technique for established the equivalence of Adenine and Thymine; Guanine and Cytosine. This is most effective method for water purification. Complete deionization of water (or) a non-electrolyte solution is performed by exchanging solute cations for hydrogen ions and solute anions for hydroxyl ions. This is usually achieved by method is used for softening of drinking water. Proteins are also successfully separated by this technique. It is also used for the separation of many vitamins, other biological amines, and organic acids and bases.

One of the main disadvantages of ion exchange chromatography is its buffer requirement: because binding to IEX resins is dependent on electrostatic interactions between proteins of interest and the stationary phase, IEX columns must be loaded in low-salt buffers. For some applications, this restriction may require a buffer exchange step prior to ion exchange chromatography.