Electromigration behavior of polysaccharides in capillary electrophoresis under pulsed-field conditions.

Various polysaccharides can successfully migrate through entangled polymer solutions during high-voltage capillary electrophoresis. For neutral polysaccharides, complexation with borate provides the electric charge needed for electromigration, while a fluorescent tag is needed to detect the solute bands with adequate sensitivity. At constant potentials between 50 and 300 V/cm, the charged polysaccharides undergo molecular stretching, resisting the desired separation according to their molecular mass. This problem can be overcome through the use of variable fields, pulsed along the separation capillary at a 180 degree angle. Variables of the pulsing experiment appear to have a profound influence on molecular shape rearrangements of polysaccharides with respect to the separation medium, as demonstrated here with highly efficient separations of polydextrans (8,000-2,000,000 Da).