Abstract: This disclosure relates to an affinity polymer composite comprising a product of reacting a precursor mixture comprising at least one cross-linking monomer component having two or more ethenyl moieties suitable for polymerization; wherein the affinity polymer composite has a first binding energy with a purine compound that is at least 1 kcal/mole more favorable than a second binding energy with a flavor compound in a complex mixture. Some embodiments include a filtration medium comprising the affinity polymer composite described herein, wherein the affinity polymer composite has a primary particle diameter of about 45 micrometers to about 150 micrometers. Some embodiments include a filtration column comprising the filtration medium described herein. Some embodiments include a method for the removal of a purine compound from a complex mixture using the filtration medium described herein.