To separate large biomolecules, such as peptides and proteins by reversed phase (RP), the pore size of the support particle is an important consideration. Because retention can be strong and the mobile phase contains an organic modifier, RP is usually avoided with proteins that are needed to be recovered in their active forms. Tosoh Bioscience offers reversed-phase columns for biopolymer separations packed with silica or methacrylate particles. The hydrophilic backbone of polymer-based reversed phase columns improves recovery and reduces secondary interactions. The polymethacrylate particles are also stable from pH 1 to 12 and do not swell in organic solvents; they can withstand rigorous cleaning with either acid or base. TSKgel Octadecyl-NPR columns are packed with non-porous methacrylate particles of uniform 2.5 micron size for high efficiency separations and fast analyses of peptides and proteins. The non-porous particle structure limits product isolation to sub-microgram loads.