Ion Exchange Chromatography is a technique for ionic separation based on exchange with resins in stationary phase and the eluents in mobile phase. These stages are based on the exchanges in an anion column to attract anions or in a cation column to attract cations. cations. A column measures the conductivity of a particular ion based on its affinity/attraction to it. The speed of movement of ions through the ion chromatograph columns depends not only on the diameter of the column but basically on the affinity of the ion to the specific resin or elute selected, the size of the interacting molecules and also the resultant distance between them based on the degree of attraction and repulsion. The ions with strong affinity for resin pass faster through the eluent as compared to the ions which have weaker affinity, which take more time to be …show more content…
In a Cation Exchanger, pH range of 0.5 – 1.5 units lesser than the isoelectric point of the protein of interest is chosen. These are the stable ranges of the pH in which either the polypeptide will get attached or get eluted. If this range is not maintained, and the pH is highly increased or decreased beyond its stability range, then the polypeptide will get denatured. Equilibration – For the system to be ready for ion exchange the starting conditions are set up. All the mobile ions get attached to the opposite charge of the stationary phase resin molecules. This happens when the right buffer conditions are applied. When this kind of conditions are successful where ions are completely attached to the resin, then equilibrium is said to have reached. Sample Application –The sample is loaded inside the column using a syringe, typically. The neutral proteins or the one with similar charge as the resin will get eluted and the ones with the opposite charge get attached to the resin