To concentrate or desalt dilute solutions, use Ultracel regenerated cellulose membranes. The hydrophilic, tight microstructure of Ultracel membranes assures the highest possible retention with the lowest possible adsorption of protein, DNA or other macromolecules. To concentrate or desalt higher volumes of more concentrated samples (recommended for protein concentrations greater than 1.0 µg/mL), use Biomax polyethersulfone (PES) membranes. These membranes are recommended for samples such as serum, plasma, or conditioned tissue culture media.