STUDY OF THE STERIC PARTITION-COEFFICIENT IN SIZE-EXCLUSION CHROMATOGRAPHY BY MONTE-CARLO SIMULATION

Monte Carlo generation of polymer chains allows evaluation of the ster ic partition coefficient, K, for any pore shape and any chain flexibil ity. This in turn enables the chromatographic radius of macromolecules , R(c), to be defined as the radius of a sphere with the same K value and allows the ratio R(c)/R(eta) to be studied. R(eta) is defined as t he radius of the sphere with the same product [eta]M, where M is the m olar mass and [eta] the intrinsic viscosity. R(c) is shown to depend o n the pore geometry. For a given pore geometry, R(c)/R(eta) is not str ictly independent of the flexibility and the relative thickness of the macromolecule. Experimentally, for flexible polymers, the so-called u niversal calibration is often found to work well. However, simulations show that the universal calibration is not strictly valid and deviati ons are expected in particular when the global flexibility of standard and sample are different.