Supercritical fluid-solid chromatography using a carbonaceous stationary phase

Abstract

Results from a preliminary evaluation of a porous glassy carbon (PGC) material for packed-column supercritical fluid chromatography (SFC) are reported. The material is characterized in terms of its retention characteristics. Increasing temperature at constant pressure causes initial increases in solute capacity factors with subsequent slow decreases when sufficient temperatures ({approx}145{degree}C) are reached. Variation of temperature at constant carbon dioxide mobile phase densities yields enthalpies of interaction for low molecular weight organics (C{sub 8}-C{sub 12}) from {minus}0.5 to {minus}1.5 kcal/mol. PGC is highly retentive; use of a supercritical fluid mobile phase that competes with solutes for adsorption onto the PGC allows significant control of solute retention. PGC offers potential advantages not provided by other materials. PGC-SFC exhibits reverse-phase characteristics similar to those found for PGC-HPLC, retention behavior previously unavailable in SFC. PGC is highly stereospecific and will be useful in SFC applications requiring separations of isomers and molecules with only slight structural differences.