Size separation of polystyrene sulfate particles (189 to 1085 nm radius) in solutions of methyl-hydroxypropyl-cellulose of different chain lengths

Polystyrene sulfate particles of 189 to 1,085 nm radius are retarded in their electrophoretic migration in solutions of methyl-hydroxypropyl-cellulose (4,000 and 15,000 cP viscosity for a 2% solution). The retardation is proportional to polymer concentration and increases inversely with particle size. This suggests a separation mechanism based on size-dependent exclusion from the polymer network, as found previously in other liquid polymer media. In the size range of approximately 200 to 600 nm radius, the 4,000 cP polymer exhibits a steeper decrease of retardation with particle size than the 15,000 cP polymer, but fails to exhibit any size dependent retardation beyond that range.