CYANOBIPHENYL-SUBSTITUTED POLYMETHYLSILOXANE ENCAPSULATED PARTICLES FOR PACKED CAPILLARY COLUMN SUPERCRITICAL-FLUID CHROMATOGRAPHY

Nine isomeric cyanobiphenyl-substituted (25%) polymethylsiloxane (CBP) stationary phases were coated and immobilized by free-radical crossli nking on silica packing materials for use in supercritical fluid chrom atography (SFC). The selectivities of these packing materials to benze ne derivatives, polycyclic aromatic hydrocarbons (PAHs), and double bo nds in fatty acid methylesters (FAMEs) were determined. Among the nine isomeric CBP-coated packing materials, the o, p-CBP phase was found t o be the most selective to both double bonds and aromatic isomers unde r SFC conditions. The durability of the packing; materials was evaluat ed by measuring the changes in selectivity with SFC use. The loss iri selectivity was less than 0.20% after being continuously washed by sup ercritical carbon dioxide at 100 degrees C and 300 atm for more than 1 00 h. (C) 1995 John Wiley & Sons, Inc.