Supercritical fluid extraction
Capillary gas chromatography
Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Summary The potential advantages of supercritical fluid extraction (SFE) over other extraction technologies stem from the properties of supercritical fluids. Specifically, the gas-like viscosities of supercritical fluids permit the rapid penetration of pores in a solid matrix (e.g. soils and sediments). Moreover, the high diffusion coefficients of solutes in the supercritical fluid media permit rapid mass transfers out of complex matrices. Typical SFE times range from a few minutes to less than one hour depending on the complexity of the sample matrix and the relative solubilities of the respective solutes of interest. The use of SFE can improve productivity with regards to both time and extraction efficiencies. Supercritical CO2 allows the extracting solvent to be vaporized while transferring the extraction effluent directly to a gas chromatograph. Since typically low temperatures (ambient to 100°C) are used in SFE, thermally labile components can be safely extracted. By changing solvent strengths, namely, using different supercritical fluids, modifiers, or densities (i.e., presures and temperature) different extraction selectivities are possible for specific solutes or classes of compounds. This paper will focus on and demonstrate the applicability of the direct coupling of SFE to a capillary gas chromatograph, and the use of SFE/GC for quantitative analysis. This will be demonstrated in terms of percent recoveries and transfer reproducibilities. Highlighted applications will include the determination of purgeable halocarbons in sediment, polynuclear aromatic hydrocarbons in carbon black, and hydrocarbons in crude oil source rocks.
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