Separation system for fractionation of polyacrylamide by gel permeation chromatography

Samples of polyacrylamide were prepared by radical polymerisation of monomer in aqueous solution. Fractions of polyacrylamide were produced by a fractional precipitation technique with methanol as non-solvent. Molecular weights of the polyacrylamides were determined by solution viscometry. Analytical gel permeation chromatography (GPC) of the polyacrylamide samples and fractions was performed with porous silicas having a chemically bonded aminopropyl phase and with an eluent consisting of formamide-water (1:5). The GPC retention results indicated the successful separation of polyacrylamides having molecular weights in the range 10⁴–10⁶. GPC of polyacrylamide with this separation system appeared to be dominated by a steric exclusion mechanism.