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Industrial and Polymer Applications 329

Figure 12.22 SFC–GC analysis of aromatic fraction of a gasoline fuel. (a) SFC trace;
(b) GC trace of the aromatic cut. SFC conditions: four columns (4.6 mm i.d.) in series (silica,
silver-loaded silica, cation-exchange silica, amino-silica); 50 °C; 2850 psi; CO 2 mobile phase
at 2.5 mL min; FID detection. GC conditions: methyl silicone column (50 m 0.2 mm i.d.);
injector split ratio, 80:1; injector temperature, 250 °C; carrier gas helium; temperature pro-
grammed, 50 °C (8 min) to 320 °C at a rate of 5 °C/min; FID detection. Reprinted from
Journal of Liquid Chromatography, 5, P. A. Peaden and M. L. Lee, ‘Supercritical fluid chro-
matography: methods and principles’, pp. 179–221, 1987, by courtesy of Marcel Dekker Inc.

onto the second column. The first column was an aminosilane stationary phase
packed column and gave good resolution of the coal tar extract by chemical class
separation (i.e. of aromatic rings) due to high selectivity. The second column was an
open tubular fused-silica column (10.5 m 50 m i.d.) coated with a liquid crys-
talline polysiloxane stationary phase. The compounds were separated on the second
column according to shape-selective separation of the isomeric compounds, thus
leading to increased efficiency. By using a packed first column, this increased the
loading capacity and increased sample concentration, which may not be obtained
with an open tubular column.