What is the purpose of the Wash Buffer (WB) in chromatography?

The purpose of the Wash Buffer (WB) in chromatography is to remove unbound proteins. During the chromatography process, proteins are typically loaded onto a column where specific binding conditions are applied. The Wash Buffer is used to gently wash the column after the initial binding step, ensuring that any proteins that did not bind to the column or were only loosely associated with it are removed. This purification step helps to increase the purity of the desired protein by clearing away contaminants or non-specifically bound proteins.

Maintaining a specific ionic strength is important in chromatography, but that is not the primary role of the Wash Buffer. The viscosity of the buffer may have technical implications for the flow through the column but is not a direct function of the Wash Buffer’s purpose. Moreover, the goal is not to elute all proteins with the Wash Buffer; that would defeat the objective of purifying the target protein. Instead, the Wash Buffer is carefully formulated to retain the bound proteins while washing away those that are not specifically retained, enhancing the overall yield and purity of the eluate in subsequent steps.