HIGH-SPEED SOLVATING GAS-CHROMATOGRAPHY USING PACKED CAPILLARIES CONTAINING SUB-5-MU-M PARTICLES

In this study, fused-silica capillaries of 250 mu m I.D. were packed w ith spherical porous and nonporous octadecyl bonded silica particles h aving diameters of 1.5 and 3 mu m. These capillaries were used with CO 2 as mobile phase at elevated temperatures. At the column inlet, the m obile phase was a supercritical fluid, while at the column outlet, it was a gas. The mobile phase gradually changed from a supercritical flu id to a gas within the column. Because the mobile phase exhibited solv ating ability for the analytes being separated, in contrast to convent ional gas chromatography (GC) in which the mobile phase is only a carr ier, this variation has been named ''solvating gas chromatography'' (S GC). Using this technique, capillaries packed with small particles pro duced column efficiencies as high as 1200 plates s(-1) for retained so lutes. Therefore, packed capillary SGC is the method of choice to carr y out high speed GC separations. The effects of column inlet pressure, column length and particle characteristics on mobile phase linear vel ocity, retention factor, column efficiency, speed of analysis and reso lution were investigated. (C) 1997 Elsevier Science B.V.