Page 336 - Multidimensional Chromatography

326 Multidimensional Chromatography

chromatograph. The determination of the heart-cut times are achieved by monitor-
ing the response from the on-line ultraviolet absorbance and flame ionization detec-
tors. A schematic diagram of the instrumental setup used for these analyses is given
in Figure 12.19.
In addition, solute focusing is possible by maintaining a low initial temperature
(e.g. 40 °C) for a long period of time (8–12 min ) to allow the mixture of decom-
pressed carbon dioxide, helium gas and the solutes to focus on the GC column. The
optimization of the GC inlet temperature can also lead to increased solute focusing.
After supercritical fluid analysis, the SF fluid effluent is decompressed through a
heated capillary restrictor from a packed column (4.6 mm i.d.) directly into a hot GC
split vaporization injector.

Figure 12.19 Schematic diagram of the interface system used for supercritical fluid
chromatography–gas chromatography. Reprinted from Journal of High Resolution Chro-
matography, 10, J. M. Levy et al., ‘On-line multidimensional supercritical fluid chromatogra-
phy capillary gas chromatography’, pp. 337–341, 1987, with permission from Wiley-VCH.