PACKED CAPILLARY COLUMN SUPERCRITICAL-FLUID CHROMATOGRAPHY USING SE-54 POLYMER ENCAPSULATED SILICA

A new method of preparing stationary phases for packed capillary colum n supercritical fluid chromatography (SFC) is presented. Surface deact ivation of silica particles was carried out by dehydrocondensation of the silicon hydride groups in polymethylhydrosiloxane with the silanol groups on the silica surface. The deactivated particles were then coa ted with a thin film of SE-54 stationary phase. The coated layer was i mmobilized by a crosslinking reaction between the methyl groups of the surface-bonded polymethylhydrosiloxane and the SE-54 stationary phase using dicumyl peroxide as a free radical initiator. With these two re actions, the polar groups on the silica surface were more completely c apped than with bonding only a monomolecular polymeric layer on the si lica surface. The SFC performance of the newly developed packing mater ials was evaluated using a standard polarity mixture, a series of fatt y acid methyl esters, a peppermint oil, and several high-molecular-mas s and complex polymers.