Fractionation of poly(ethylene glycol) by high osmotic pressure chromatography

Poly(ethylene glycol) (PEG) was fractionated by high osmotic pressure chromatography (HOPC) with water and 1,4-dioxane as eluents. Using dimethyloctylchlorosilane (C-8)-modified controlled-pore glass (CPG) with 1,4-dioxane as eluent, high molar mass (MM) PEG components were fractionated. The average MM of the fractionated PEG samples strongly depends on the eluent and the polarity of column packing materials. PEGs dissolved in water were adsorbed onto the column packing materials more easily compared with 1,4-dioxane. Comparison between simulation and experiments indicated that adsorption of PEG molecules onto the surface of the column packing materials reduces the separation efficiency of HOPC fractionation. By preventing adsorption, PEG components with higher MM and narrow molar mass distribution (MMD) were fractionated even from a commercial PEG with narrow MMD.