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