A new model has been developed for inverse gas chromatography experiments for binary polymer-solvent systems. The model includes both bulk and surface effects and has been solved using the method of Laplace transforms. Retention data near the glass transition temperature were collected from the literature and correlated and predicted with the model. Frequently investigators estimate a polymer's glass transition temperature (T-g) from the Z-shaped retention data that often occur in this temperature range. The results presented here suggest that there is little or no correlation between the Z-shaped retention diagram and the glass transition temperature. New results are also presented on the origins of the Z-shaped retention diagram and on how a combination of bulk absorption, bulk diffusion, and surface adsorption contribute to it.