THEORY OF CONCENTRATION EFFECTS IN GEL-PERMEATION CHROMATOGRAPHY

The change in elution volume following a change in the concentration of injected polymer solution in GPC is due to many contributing processes. In the theoretical model, three basic contributions are taken into account, namely, a change in the effective size of permeating molecules and thus a change in the distribution coefficient according to the respective calibration curve; viscosity phenomena in the interstitial volume; and, finally, secondary exclusion. The first two contributions lead to an increase in elution volumes, while the last, secondary exclusion, causes reduction in elution volumes with increasing concentration. Changes in the concentration of injected polymer solution were also considered which occur directly at the beginning of the column due to the distribution between the mobile and the stationary phase and also due to the longitudinal spreading. Mutual proportions between the individual contributions to the overall concentration effect were calculated. The relationships derived using dimensionless quantities may be interpreted as a calibration function explicitly involving the effect of concentration. © 1979, American Chemical Society. All rights reserved.