History of supercritical fluid chromatography: instrumental development.

In the early days of supercritical fluid chromatography (SFC), it was categorized as high-pressure or dense gas chromatography (HPGC or DGC) and low boiling point hydrocarbons were used as supercritical mobile phase. Various liquids and gases were examined, however, by the late 1970s, carbon dioxide (CO₂) became the most preferred fluid because it has low critical temperature (31.1°C) and relatively low critical pressure (7.38 MPa); in addition, it is non-toxic, non-flammable and inexpensive. A prototype of a modern packed-column SFC instrument appeared in the late 1970s. However, in the 1980s, as open tubular capillary columns appeared and there was keen competition with packed columns. And packed-column SFC at once became less popular, but it regained popularity in the early 1990s. The history of SFC was of "the rise and fall." Advances in chiral stationary phase took place in the early 1990s made packed-column SFC truly useful chiral separation method and SFC is now regarded as an inevitable separation tool both in analytical and preparative separation.