The preparation of affinity chromatography resins through coupling bio-specific ligands to pre-activated resins represents a well-established and widely applied technology. NHS-activated Singarose 4 FF is a pre-activated agarose-based affinity chromatography resin with a 4% highly cross-linked agarose matrix, exhibiting excellent physical and chemical stability. This resin is commonly used for coupling primary amine-containing proteins or other molecules to form chemically stable peptide bonds, making it particularly suitable for immobilizing small molecule proteins and peptide ligands. The highly cross-linked pre-activated resin incorporates 6-aminocaproic acid as a spacer arm attached to Singarose 4 FF, with its terminal carboxyl group activated via hydroxy succinimide esterification. Ligands containing primary amine groups can be directly coupled to the activated ester, forming chemically robust peptide bonds primarily used in the separation and purification of proteinaceous biomolecules.