The present disclosure provides materials and methods related to the purification of a biologic from a biological fluid. In particular, the present disclosure provides compositions, and related methods, comprising peptide ligands capable of removing process-related impurities (e.g., host cell proteins, nucleic acids, and media components) and product-related impurities (e.g., product fragments, product aggregates, and inactive forms derived from product degradation by or association with other species in the cell culture harvest) from biological fluids during the production of a biologic.