An attempt to extend ordinary capillary gas chromatography to supercritical fluid chromatography (SFC)

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Abstract
Since capillary columns with well immobilized stationary phases are expected to withstand contact with supercritical fluids, we wished to study their amenability to SFC. Simultaneously, we wished to learn how far SFC can be accomplished with the ordianary tools of capillary GC.The study demonstrates that truly supercritical, not just relatively high, pressure is required to ensure the typical effects of SFC. Results obtained with sub‐and supercritical pressure are compared and discussed. A comprehenshive study of the parameters permitting SFC with capillary GC equipment showed a clear preference for CO2 as a carrier, FID detection, and oncolumn sampling. While no additional equipment is required, a critical feature is the flow restrictor to be mounted on the end of the column. The production and properties of this restrictor are discussed in detail. It is reasonable to hope that SFC with 0.1 mm id capillary columns can be realized in the pressure range of 100–150 bar, where substances which cannot be eluted from a capillary colum under GC donditions are expected to be analyzed.