Gels of syndiotactic polystyrene (sPS) in a binary mixture of 1,2-dichloroethane (DE) and 1-chlorotetradecane (CTD) have been investigated by attenuated total reflectance-Fourier transform infrared spectroscopy. Host-guest interactions into the clathrate phase induce not only the well-known selectivity in favor of the trans conformer but also a well-defined shift of the CH2 wagging mode of such conformer. Independent evaluations of the DCE content in the polymer-rich and polymer-poor phases, based on DCE conformer equilibrium and peak shift, give essentially identical results. As a consequence, an accurate evaluation of the amount and composition of the polymer-poor and polymer-rich phases of these gels from binary solvent mixtures can be achieved.