Chromatographic separation immobilized metal affinity

Immobilized-metal affinity chromatography (IMAC) is a separation technique that uses covalently bound chelating compounds on solid chromatographic supports to entrap metal... 

Metal interaction chromatography is an HPLC technique that can separate many biopolymers because of their differential ability to form complexes with metal ions [1]. It employs a stationary phase with an appropriate metal immobilized via chelating functions bound to the surface. Retention and separation of the sample components occur largely by their interaction with the chelated metal. Although immobilized metal affinity chromatography (IMAC) is a common name for the technique, it is called metal interaction chromatography (MIC) in this book to conform to the nomenclature used for the other interactive chromatographic methods for biopolymer separation by HPLC. 

Particularly, immobilized-metal affinity chromatography (IMAC) is a separation technique that uses covalently bound chelating compounds on solid chromatographic supports to chelate metal ions, which serve as affinity ligands for various proteins, making use of coordinative binding of some amino acid residues exposed on the surface. Most commonly used are Cu(II), Ni(II), Zn(II), Co(II), and Fe(III) transition-metal ions, which are electron-pair acceptors and can be considered as Lewis acids. MAC technique can be used to separate proteins and peptides, with exposed histidine residues, which are primarily responsible for binding to immobilized metal ions. 

Ion-exchange chromatography (lEX) has been used for more than 50 years for the separation and purification of proteins. In comparison with other chromatographic methods, 40% of all protein separations are related to lEX, 18% to SEC, and 29% to affinity chromatography (including immobilized-metal-affinity and dye-affinity chromatography) [1]. 

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