ABSTRACT
Supercritical fluid extraction (SFE) is a technique in which the extracting “liquid” is a supercritical fluid. The sample is usually in a solid or semisolid state and, in environmental applications, can be sludge, soil, sediment, or biological tissue. Even liquids may be extracted by SFE if the liquids are first passed through a solid phase extraction (SPE) material, such as an Empore filter, to sorb the analytes of interest onto a solid bed, with the solvent (not of analytical interest) passing to waste. The solid phase material containing the analytes of interest is then placed in the SFE extraction vessel for the last stage of sample preparation. Examples of this will be discussed in later sections of this chapter.
