Corning Spin-X UF centrifugal concentrators offer a simple, one step procedure for concentrating or desalting proteins and other biomolecules with 90% or better recovery. Integrated dead stop design eliminates risk of spinning to dryness; no respinning necessary Spin-X UF 6 for samples up to 6 mL Low binding polyethersulfone (PES) membranes are available with five molecular weight cut-offs (MWCO): 5,000, 10,000, 30,000, 50,000 and 100,000 to meet all of your concentrating needs. Choose an MWCO 1/2 to 1/3 smaller than the protein to be concentrated. The MWCO and graduations are printed right on the side of the concentrator tube to avoid mix-ups. Spin-X UF 6 concentrators can be used with either swinging bucket or fixed angle rotors minimum rotor angle is 25º.