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Title: HELIUM ENTRAINED CO2 AND OTHER BINARY CO2 GAS MIXTURES FOR SUPERCRITICAL FLUID EXTRACTION OF LIPID RICH SAMPLES

Author
item Zhang, Zhouyao
item King, Jerry

Submitted to: Pittsburgh Conference
Publication Type: Abstract Only
Publication Acceptance Date: 3/21/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: When SFE is used for residue chemical analysis of lipid rich samples, a time consuming clean-up step is often necessary to remove the lipid content from extracts before GC analysis. This lipid solubility in supercritical fluid can be significantly reduced when helium entrained CO2 is used as a gas source, although the reason for this phenomenon is not fully understood. In this study, an Anton Parr density meter and GC equipped with a thermal conductivity detector have been used to monitor the density and composition of the supercritical fluid generated from a helium headspace (HHS) CO2 cylinder over the duration of its use. The highly accurate density measurements (up to 10**-4 g/mL) show that the supercritical fluid density from HHS CO2 is 2-4% lower than that from a pure CO2 source. The reduction in density is the result of helium entrainment in CO2 when HHS CO2 is used. Solubilities of a soybean oil in supercritical fluids with different helium compositions have been measured and related to both supercritical fluid density and composition. A binary CO2 gas mixture with nitrogen can be used to extract pesticide residues in chicken fat. Because of the low solubility of fat in the supercritical CO2 binary mixture, selective extraction of trace pesticides devoid of lipid content is possible. This new approach minimizes the need for clean-up of lipid matter after SFE.