CORRELATION BETWEEN COLUMN SURFACE-AREA AND RETENTION OF POLAR SOLUTES IN PACKED-COLUMN SUPERCRITICAL FLUID CHROMATOGRAPHY

The retention of organic acids, amines, aminophenols, and amides was directly proportional to the surface area of Diol coated silica particles. Surface area was measured in situ using the method of Hong and Parcher [Anal. Chem., 62 (1990) 2313-2317]. Linear regression analysis was performed on the results from four pore diameters (100, 300, 500 and 4000), plus the origin. Correlation coefficients between retention and surface area were as high as 0.9991. Both the surface area of the chromatographic support and solute retention changed by more than 14 times. All the solutes tested behaved similarly, indicating that changing the surface area is a viable means of retention control. The smallest pore diameter tested (100 angstrom) produced the same efficiency as some of the larger pore sizes (i.e., 300 and 500 angstrom) suggesting that still smaller sizes, like 60 angstrom, might be useful for supercritical fluid chromatography. Particles with 4000 angstrom pores produced poor efficiency, due to peak tailing, which suggests that deactivation was inadequate.