Submitted to: Federation of Analytical Chemistry and Spectroscopy Societies Final Program
Publication Type: Abstract Only
Publication Acceptance Date: October 20, 1995
Publication Date: N/A
Technical Abstract: Extraction enhancement or suppression in supercritical fluid extraction (SFE) is important for controlling the processes' selectivity with respect to isolating the desired target analyte(s). In this presentation, we shall report on methods and the use of physicochemical data to optimize the extraction, fractionation, and recovery of solutes utilizing supercritical fluids. Techniques which have proven useful in controlling the selectivity of supercritical fluids are changing the supercritical fluid (CO2 vs. HCF3), the introduction of fluids lower in TCS than CO2, the use of binary extraction fluids or cosolvent addition, and the suppression of extraction or solubility solute by sorbent moderation. The use of these techniques will be illustrated for the determination of pesticides in fat-containing matrices, cholesterol analysis in food products, and lipid speciation in natural products. Finally, the use of physicochemical data such as viral and activity coefficients, as well as chromatographically-derived measurements can be used to optimize the extraction and recovery solutes (analytes) with and from supercritical fluid media, respectively. Several examples will be given on how the magnitude and sign of the second mixed gas-solute viral coefficient, the activity coefficient of the analyte in trapping solvent, and the chromatographically-measured specific retention volumes can influence the choice of extraction and collection conditions in SFE.