Ion Exchange Chromatography Selection Guide
Introduction and Product Selection Table
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:
|Type of Ion Exchanger||Common Abbreviation||Functional Group||Pall Product|
|Strong Anion||Q||Quarternary Ammonium||
|Weak Anion||DEAE||Diethylaminoethyl||DEAE Ceramic HyperD® F
AcroSep with DEAE Ceramic HyperD® F
|Strong Cation||S||Sulfonic Acid||Mustang S
Acrodisc with Mustang S
AcroPrep with Mustang S
|Weak Cation||CM||Carboxymethyl||CM Ceramic HyperD® F
AcroSep with CM Ceramic HyperD® F
Pall 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.
What Flow Rate to Use?
What Buffer to Use?
What pH to Use?
What Salt to Use for Elution?
The effectiveness of displacement for commonly used cations is: Ca2+ > Mg2+ > Na+ > K+ >NH4+
The order of displacement effectiveness for commonly used anions: PO43- > SO42- > COO- > Cl-
These rankings correlate with the Hofmiester series, and the strongest eluting salt is not always best. Ideally, several salts should be tested, and finding optimum elution conditions often involves trial and error. Most users will start with either NaCl or KCl simply because they are readily available in the lab. However, CaCl2 or MgCl2 may be used. For some proteins, those salts may actually end up being a better choice. Regardless of eluting salt selection, the effect on the purity, stability, and activity of the target molecule will have to be assessed.