Dialysis is a process where substances in solution are separated by their differences in molecular weight. The dialysis tubings are semipermeable, made of regenerated cellulose or cellulose ester having a gel-like structure. The driving force is the concentration difference between 2 solutions on opposite sides of the membrane. 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.

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. 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.

For many years, dialysis has been successfully used as a routine method for desalting and concentration of complex biomolecules in solution. In addition, macromolecules, differing substantially in molecular weight can be separated.


  • Desalting of protein solutions, e.g. for further purification by ion exchange chromatography
  • Concentration of protein solutions by embedding the filled tubing in dry PEG 20000 (cat. no. 33138) e.g. before further separation by gel permeation chromatography
  • Separation of high molecular weight proteins from low molecular weight peptides and other substances
  • Buffer exchange with solutions of proteins or other macromolecules
  • Desalting of metallo colloids


Product of the Month February:
Xpress Dialyzer

Western Blotting - New Brochure!
ICPL™ Quadruplex Plus Kit -

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SERVA Market Square:

February - March 2017

Save up to 30 % :

  • Antibiotics
  • Buffers and Buffer Solutions
  • Detergents
  • Staining Reagents
  • Western Blotting

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Product of the Month February:
Xpress Dialyzer

Fast Dialysis of Small Sample Volumes (10 - 1000 µl)

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The SERVA Catalog 2017/18:


• Biochemicals A-Z

• Sample Preparation

• Electrophoresis

• Laboratory Equipmeng

• Collagenase & Neutral Protease

• Life Sciences

• Enzymology

• Microscopy

• Ion Exchange Media

• Pharmacopoeia

Find the SERVA Online Catalog 2017/18 here!
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SERVA BlueNews 6/2016

Please find the latest information
on new products and services here:

• 1D SDS TA Gels
• EPO Doping Analytics
• DNADecon
• New Tools in Dialysis
• Product of the Month
• Western Blot Workflow
• Sample Preparation by Protein Ark
• LED Gel Scanner BIO-1000F
• Collagenase AF GMP Grade
• Top Ten YouTube Videos

BlueNews: Issue June 2016.pdf
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New Application Note:
ICPL™ - Coupled Immunoprecipitation

ImmunoPrecipitation (IP) is widely used as a method to selectively isolate protein complexes from primary tissues. However, due to lack of specificity and selectivity of most antibodies and unspecific binding of the carrier beads, the method can produce false positives. The ICPL approach, employing stable isotope labelling and mass spectrometry, can discriminate true positive from false positive IP complexes.

SERVA ICPL™ Quadruplex Plus Kit 39233
Application Note: ICPL-IP
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