Thermo Scientific Slide-A-Lyzer Dialysis Cassettes (20K MWCO) facilitate simple and effective removal of buffer salts and small contaminants from proteins and other macromolecules that are larger than 20,000 daltons.The cassettes are constructed from two sheets of low-binding, regenerated-cellulose dialysis membrane that are hermetically sealed on either side of a silicone-like gasket inside an inert plastic frame. The membrane and cassette materials are compatible with most common laboratory chemicals and buffers. Liquid samples are easily added and removed by penetrating the self-sealing gasket with a hypodermic needle attached to a syringe. No knots, clips or caps are needed to seal the units and prevent leaking and sample-loss during the dialysis procedure.20K Dialysis Membrane Specifications:Composition: Regenerated cellulose synthesized by the Viscose method Thickness: 0.9 to 1.2mil (22.5 to 30µm) Hydration Required Before Use: 2 minutes Glycerol Content: None Sulfur Content: 0.04% Heavy Metals Content: Trace Highlights:Four cassette sizes – select the cassette that best suits your sample volume Color-coded – purple cassette frame specifies cassettes with the 20,000 MW pore size membrane Easy to use – no knots or clamps are needed; just inject sample into cassette and begin dialysis Fast dialysis – flat cassette chamber with two membranes provides high surface-area to volume ratio that maximizes diffusion rate compared to cylindrical dialysis tubing High recovery – rectangular cassette design maximizes recovery of entire sample volume via any one of the four corner injection ports