Ion exchange chromatography separates compounds based on net surface charge. Molecules are classified as either anions (having a negative charge) or cations (having a positive charge). Some molecules (e.g., proteins) may have both an anionic and cationic group. A positively-charged support (anion exchanger) will bind a compound with an overall negative charge. Conversely, a negatively-charged support (cation exchanger) will bind a compound with an overall positive charge.
Ion exchange matrices can be further categorized as either strong or weak. Strong ion exchange matrices are charged (ionized) across a wide range of pH levels. Weak ion exchange matrices are ionized within a narrower pH range. The four most common ion exchange chemistries are shown here:
[table=98%]
[td=1,1,36%]Type of Ion Exchanger [td=1,1,30%]Common Abbreviation [td=1,1,29%]Functional Group
Membrane Solutions offers ion exchange resins, pre-packed columns, and membranes. In many areas, chromatography resins are the media of choice for chromatography applications, but in some cases where resin-based methods have limitations (e.g., purification of viruses or large molecules) membranes have proven to be a robust, scalable, and economic alternative. Membranes perform well in such applications because of their faster flow rates compared to resins.