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

Poly(ethylene glycol) (PEG) was fractionated by high osmotic pressure chrom atography (HOPC) with water and 1,4-dioxane as eluents. Using dimethyloctyl chlorosilane (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. C omparison between simulation and experiments indicated that adsorption of P EG molecules onto the surface of the column packing materials reduces the s eparation efficiency of HOPC fractionation. By preventing adsorption, PEG c omponents with higher MM and narrow molar mass distribution (MMD) were frac tionated even from a commercial PEG with narrow MMD.