CAPILLARY SUPERCRITICAL FLUID CHROMATOGRAPHY AT PRESSURES ABOVE 400 ATM

Selectivity and efficiency advantages often occur in capillary supercritical fluid chromatography (SFC) when the column temperature is raised. However, the slopes of the mobile phase density-pressure Isotherms drop with increasing temperature. Commonly used SFC pumps (and other chromatographic components) specify a somewhat arbitrary pressure limit, often around 400 atm. This results in a severe reduction of the accessible density range (and mobile-phase strength range) when higher temperatures are chosen. The potential of using capillary SFC with pressures up to 560 atm to extend the range of eluted solutes is demonstrated with several chromatograms. Eventually, the permissible temperature ranges for typical SFC columns must be determined in the presence of high-pressure mobile phase. Then the upper pressure limit required, corresponding to the maximum density desired with each mobile phase at its upper temperature limit, can be specified. © 1990, American Chemical Society. All rights reserved.