Diethylaminoethyl cellulose chromatography is a weak anion-exchange mode in which diethylaminoethyl groups are covalently attached to a cellulose matrix. The tertiary amine groups are protonated over the usual working range, giving the stationary phase a positive charge that reversibly binds negatively charged solutes ^[1]. Retention depends on the solute’s net charge, the buffer pH, ionic strength, ligand density, and accessibility of exchange sites within the hydrated cellulose. Bound species are released by increasing the concentration of a competing salt or by changing pH to reduce the charge difference between solute and exchanger ^[2]. The method is distinct from cation-exchange chromatography on carboxymethyl cellulose, from size-exclusion separation by pore access, and from affinity chromatography based on a biospecific ligand. Its necessary elements are a DEAE-functionalized cellulose stationary phase, an aqueous mobile phase that controls ionization, and reversible electrostatic exchange as the dominant retention mechanism.