Spectroscopic measurement of solute and cosolvent partitioning between supercritical CO2 and polymers

Cosolvents exhibit significant effects on the partitioning behavior of dilu te solutes between a supercritical CO2 fluid phase and cross-linked siloxan e-based polymers. A spectroscopic technique was developed and applied that allows us to measure the partition coefficients of both the cosolvents and solutes between the two phases. The Sanchez-Lacombe lattice fluid equation of state was extended to represent a two-phase, four-component system and w as quantitatively successful in representing the volumetric and phase-equil ibria properties of such systems. We then apply the model and our data to i nvestigate the magnitudes of stationary-phase effects in supercritical flui d chromatography and explore opportunities to use the model for a priori pr ediction of separation.