Pore flow effects in electrically driven size-exclusion chromatography

The applicability of electrically driven (ED) size-exclusion chromatography for the separation of synthetic polymers was investigated in capillary columns packed with 5 mu m particles with different pore sizes using dimethylformamide as the mobile phase. It was found that under ED conditions a significant intraparticle pore flow was generated. The relative intraparticle velocity with respect to the average interparticle velocity increased with the pore size and ionic strength. It was also observed that with increasing pore flow the plate height of polymers decreased considerably. On the other hand, the intraparticle velocity impaired the selectivity of the separation. In some cases the loss in selectivity was so large that hardly any separation of polymers was achieved. The effect of pore flow on the retention of polymers in porous particles could be described well with a simple theory. (C) 1999 Elsevier Science B.V. All rights reserved.