Current Trends

upercritical fluids have been used as unique solvents in a number of analytical techniques (l), such as nuclear magnetic resonance spectroscopy (2), thin-layer chroma-tography (TLC) (3), and field flow fractionation (4). The ana-lytical chemist, however, normally associates the prefix “supercritical fluid ” with chromatographic or extraction meth-odologies that have been extensively developed within the past 15 years. The “renaissance ” of supercritical fluid chromatogra-phy (SFC) occurred in the mid-1970s, largely as a result of improvements in injection and pumping devices, enhanced column efficiencies, and the refinement of transport mecha-nisms to deliver the separated solutes to modified gas (CC) and liquid chromatographic (LC) detectors (5). By contrast, super-critical fluid extraction (SFE), despite a long history as a phys-icochemical phenomenon (6) and a recent plethora o