Carbon dioxide based supercritical fluid chromatography

Carbon Dioxide Based Supercritical Fluid Chromatography... 

Supercritical fluid chromatography uses most of the same or slightly modified hardware. The greatest difference is that most of the normal liquid used as the mobile phase in HPLC is replaced with a liquefied gas, like carbon dioxide. Fluids other than carbon dioxide can be used, but for all practical purposes, SFC means C02-based chromatography. 

Supercritical fluid chromatography has at least one extra control variable compared to HPLC. Many people still associate the name SFC with syringe-pump-based systems in which pure carbon dioxide was used with pressure programming. Modern SFC sometimes still operates in this manner but only for nonpolar solutes. SFC is somewhat different from HPLC. It is useful to discuss the relative effects of different control variable on retention and selectivity. The relative effects of several control variables are represented schematically in Fig. 5. 

The method based on immunosorbents coupled on-line with liquid chromatography-atmospheric pressure chemical ionization mass spectrometry [109], discussed in section 9.4.2.1, has been applied to the determination of substituted urea type herbicides. Supercritical fluid extraction with methanol modified carbon dioxide has been applied to the determinants of sulfonyl urea herbicides in soil [261],... 

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