ABSTRACT
Another approach for separation is to adjust chromatographic conditions to maximize chemical or apparent molecular size differences of dissolved components. Then, chemically different groups can be fractionated by size exclusion stationary phases even if molecular weights are similar. In the absence of salts or buffers (to reduce charge effects) sample components may be separated due to factors other than molecular weight. Distilled water may increase the apparent molecular size of ionic dissolved components due to hydration layer formation or other hydrogen bonding or ionic repulsion mechanisms. Sample column interactions, causing fractionation, may result from charge attractions or repulsions in the absence of salts or buffers in the mobile phase.
