Immobilized textile dyes, most commonly sulfonated triazine dyes such as Cibacron Blue F3GA, constitute the ligand class that defines dye affinity chromatography. The dye is covalently attached to a hydrophilic chromatographic matrix and presents a planar, charged, and hydrogen-bonding surface that mimics nucleotide cofactors or other binding pockets, so that a subset of proteins, enzymes, and certain polysaccharides is retained by a combination of electrostatic, hydrophobic, and pseudoaffinity contacts ^[1]. Elution is effected by a competing ligand, by a change of ionic strength or pH, or by additives that weaken the dye–solute contact ^[2]. The method is therefore a form of affinity chromatography whose selectivity originates in the dye structure rather than in an antibody, lectin, or immobilized metal. Conceptual boundaries exclude ordinary ion-exchange or hydrophobic-interaction chromatography that lacks a dye ligand, and they also exclude free-solution dye precipitation. Essential features are a chemically defined immobilized dye, a matrix that does not itself dominate retention, and a reversible binding equilibrium that can be displaced without destroying the target ^[3]. Retention of both sulfated polysaccharides and nucleotide-binding enzymes confirms that selectivity follows dye–solute recognition rather than membership in a single analyte class ^[4].