LIQUID-CHROMATOGRAPHIC RETENTION BEHAVIOR OF POLYSTYRENE HOMOPOLYMERS ON A C4, BIMODAL PORE DIAMETER, REVERSED-PHASE COLUMN

The isocratic retention of a series of homopolymer polystyrenes was studied on a C4, bimodal pore diameter column using two different binary mobile-phase systems. A significant difference in retention behavior was observed between data obtained using the tetrahydrofuran:acetonitrile system, THF:ACN, as the mobile phase and data acquired using the methylene chloride:methanol system, CH2Cl2:MeOH, as the mobile phase. Using the THF:ACN system it was possible to separate isocratically a series of polystyrenes of different molecular weight, and the molecular weight range that was separated could be adjusted by changing the proportions of THF and ACN in the mobile phase. It was found that in addition to a dependence on the nature of the mobile phase, the retention behavior of polystyrenes may be affected by the exclusion properties of the column, the ability or inability of the stationary phase to preferentially adsorb one of the mobile-phase components, and the nature of the stationary phase itself.