FUNCTIONAL-GROUP SELECTIVITY USING FLUOROFORM AS A MOBILE-PHASE FOR SUPERCRITICAL-FLUID CHROMATOGRAPHY

The eluotropic strength and chromatographic selectivity of fluoroform is compared to that of carbon dioxide and methanol-modified carbon dioxide. Naphthalene derivatives were used as probe solutes in capillary supercritical fluid chromatography to determine the effects of fluid type, pressure, and temperature on selectivity and retention. Fluoroform is much stronger in eluotropic strength than carbon dioxide or methanol-modified carbon dioxide at the same temperature and pressure. Under the same reduced conditions, fluoroform is lower in eluotropic strength than carbon dioxide. Specific interactions between hydrogen bond accepting functional groups and fluoroform are observed. Functional groups capable of accepting hydrogen bonds contribute less of an increase in retention when using fluoroform while those capable of dispersive interactions contribute less of an increase in retention when using carbon dioxide.