Verdringingsmethode

Verdringingsmethode, or the displacement method, is a chromatographic separation technique in which a displacer component with higher affinity for the stationary phase competes with and displaces bound analytes. This creates a moving front that elutes the target compounds in a relatively compact, well-defined zone, often yielding higher resolution than standard isocratic elutions.

The principle relies on adsorption/desorption equilibria between the solutes, the stationary phase, and the displacer in the mobile phase. When the displacer is introduced, it occupies binding sites on the stationary phase, forcing bound solutes to desorb and form a distinct elution boundary. The resulting separation depends on differences in affinity and the strength and shape of the displacer gradient. In practice, the displacer is added as a step or gradual gradient, and the elution profile is typically sharper and more controllable than other elution modes.

Procedure and scope vary by system, but common steps include selecting a suitable stationary phase, choosing a displacer with appropriate affinity, loading the sample, applying the displacer to create the displacement front, and collecting fractions corresponding to separated components. The method is used in preparative and analytical chromatography, especially for purifying proteins, peptides, nucleotides, and other biomolecules, as well as some small-mmolar compounds, often in ion-exchange or reversed-phase contexts.

Advantages include high loading capacity, sharp elution fronts, and good resolution for certain mixtures. Limitations involve the need for careful optimization of displacer concentration and gradient shape, sensitivity to flow and temperature, and potential for band broadening if conditions are not well controlled.