How do you do ion exchange chromatography?

The general steps of ion-exchange chromatography procedure are as follows:

1. A sample with proteins to be purified is loaded onto the ion exchange chromatography column at a particular pH, which ensures that the proteins are ionized and soluble.
2. Charged proteins will bind to the oppositely charged functional groups in the resin, and uncharged impurities are wash away.
3. A salt gradient is used to elute and separate proteins. Proteins with stronger binding are eluted at a higher salt concentration. A pH gradient may also be used, but cautions should be taken to make sure proteins are stable and soluble.
4. Unwanted proteins and impurities are removed by washing the column.