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 dio xide. Naphthalene derivatives were used as probe solutes in capillary supercritical fluid chromatography to determine the effects of fluid t ype, pressure, and temperature on selectivity and retention. Fluorofor m is much stronger in eluotropic strength than carbon dioxide or metha nol-modified carbon dioxide at the same temperature and pressure. Unde r the same reduced conditions, fluoroform is lower in eluotropic stren gth than carbon dioxide. Specific interactions between hydrogen bond a ccepting functional groups and fluoroform are observed. Functional gro ups 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 ca rbon dioxide.