Ion exchange chromatography
Ion-exchange chromatography separates proteins and/or molecules according to their net charge. The stationary phase of the column will have a specific charge which is created by ion-exhcnage resins which come in two forms: polyanions (negatively charged) and polycations (positively charged).
For example negatively charged proteins (anions) will bind to a positively charged diethylaminoethylcellulose (DEAE-cellulose) columns. The negative proteins bound to column can by eluted by adding a negatively charged buffer which will compete with the protein for binding to the column. Proteins that have lower charge density will be eluted first from the column [1].
The stationary phase is an insoluble matrix which will either carry a positve or negative charge. Whilst diethylaminoethylcellulose (DEAE-cellulose) is positively charged, an negatively charged matrix includes carboxymethylcellulose (CM-cellulose) [2][3].