Biomedical Engineering Reference
In-Depth Information
Aqueous samples may be concentrated using dialysis tubing.
After dialysis, the tubing containing the sample is surrounded with
dry GPC medium, e.g., Sephadex 200, or polyethylene glycol, e.g.,
PEG 20000 (if PEG is used, parts of the polymer with significantly
lower molar mass may penetrate the membrane resulting in pre-
cipitation of the protein within the tubing). After several hours at
4
◦
C, water and buffer substances are sucked off and the volume of
the dialysate is diminished. The buffer composition is not altered
by this very smooth concentration method.
