Methylene Selectivity and Eluotropic Strength Variations in Subcritical Fluid Chromatography with Packed Columns and CO₂-Modifier Mobile Phases

This work has consisted of better understanding the chro-matographic behavior in subcritical fluid chromatography with CO(2)-acetonitrile and CO(2)-methanol mobile phases. To that end, the changes of solute solubility in the mobile phase have been studied by determination of methylene selectivity of a homologous series. Moreover, eluotropic strengths have been calculated for mobile phases containing from 5 to 45% modifier. To carry out the studies in all ranges of the subcritical area, experimental designs have been used. The influences of analytical temperature (from 10 to 30 °C) and outlet pressure (from 10 to 20 MPa) have also been investigated both on solubility and on eluotropic strength. A more general comparison of elu-otropic strengths of subFC and HPLC has been achieved.