Elution in affinity chromatography occurs after:
Affinity chromatography exploits highly specific, reversible biological interactions such as enzyme-substrate, antibody-antigen, or receptor-ligand binding. Matrix immobilized with ligand captures target molecule while others pass through. To achieve purity, initial binding step is followed by extensive buffer wash to remove unbound contaminants, then additional wash to eliminate non-specifically adsorbed molecules via low-stringency conditions. Only after clearance does specific elution occur using competitive ligand, pH shift, or high salt to disrupt interaction. Hence complete purification sequence involves ligand binding, non-specific washing, and final desorption, ensuring high-fold enrichment of desired biomolecule from crude extracts.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.