Dialysis is a simple process in which small solutes diffuse from a high concentration solution to a low concentration solution across a semipermeable membrane until equilibrium is reached. Since the porous membrane selectively allows smaller solutes to pass while retaining larger species, dialysis can effectively be used as a separation process based on size rejection. The conditions of dialysis can be controlled or manipulated to produce desired results for a variety of dialysis applications. The application depicts which Molecular Weight Cut Off (MWCO) yields the preferred molecular separation.

ADVANTAGES OF LAB DIALYSIS

• Very Gentle Conditions
  
• Easy Operation
  
• Wide Range of Sample Volumes
  
• Many Membrane Types & MWCO's
  
• Inexpensive Materials
  
• Disposable Membranes & Devices

Dialysis Applications

• Macromolecular Purification
  
• Protein Concentration
  
• Solute Fractionation
  
• Contaminant Removal
  
• pH Change
  
• Desalting
  
• Buffer Exchange
  
• Binding Studies
  
• Electro-elution

Selecting the Right Molecular Weight Cut Off (MWCO)

Since the dialysis membrane consists of a spongy matrix of crosslinked polymers, the pore rating referred to as Molecular Weight Cut Off (MWCO), is an indirect measure of the retention performance. More precisely, the membrane MWCO is determined as the solute size that is retained by at least 90%. However, since a solute's permeability is also dependent upon molecular shape, degree of hydration, ionic charge and polarity, it is recommended to select a MWCO that is half the size of the MW of the species to be retained and/or twice the size of the MW of the species intended to pass through.