Abstract: A macroporous core-shell resin bead having carboxylic acid groups; the bead has from 3% to 100% of monomer residues derived from crosslinker, an average pore diameter of at least 1.5 nm, and an average particle size from 10 pm to 900 ?m; wherein at least 90% of the carboxylic acid groups in the bead are in the shell region, and the shell region comprises from 5% to 75% of the bead by volume.

Abstract: The present invention relates to an improved method of making a resin including steam stripping porogen from a polymer under vacuum. Optionally, the method includes diluting to remove process aids, and low pressure steam stripping to effect porogen removal. The invention makes adsorbent resins, and adsorbent resins free of animal derived products. In another aspect, the invention provides for a resin made using the improved method, and a downstream product made utilizing the resin in a manufacturing process used to make the product. The downstream product is a drug or precursor thereof, and is optionally cephalosporin C and insulin.