Modes of Chromatography

There are two main modes of chromatography: 1) flow-through chromatography, and 2) bind/elute chromatography. Flow-through chromatography allows impurities to bind to the chromatography column while the target molecule passes through. In bind/elute chromatography, the column first captures the target molecule on the resin, while impurities get washed out of the column, and later in the process run time, the target molecule is released from the column resin by elution.

Flow-through Mode

• Principle: Allows impurities to bind to the chromatography column while the target molecule passes through.

• Operation:

• The column is designed so that contaminants interact with the resin.

• The target molecule flows through unbound, collected directly in the effluent.

• Advantages:

• Faster process since no elution step is required.

• Lower risk of product loss or degradation.

• Simplifies downstream purification.

• Widely used in polishing chromatography.

Bind/Elute Mode

• Principle: The column first captures the target molecule on the resin, while impurities get washed out of the column, and later in the process run time, the target molecule is released from the column resin by elution.

• Operation:

• The column is loaded so the molecule of interest adheres to the resin.

• Unwanted species are washed away.

• The target is then eluted by changing buffer conditions (e.g., increasing salt concentration or altering pH).

• Advantages:

• High selectivity and purity.

• Effective for concentrating dilute samples.

• Flexible—conditions can be tuned to optimize binding and elution.

• Widely used in capture chromatography.