Submitted to: Research and Development Magazine
Publication Type: Trade Journal
Publication Acceptance Date: 10/1/1997
Publication Date: N/A
Technical Abstract: Analytical supercritical fluid extraction (SFE) has progressed in recent years beyond the extraction mode and more specialized techniques have been developed to make the technique more analyte specific and versatile. In this overview, basic instrumentation requirements are enumerated and several specific topics addressed, namely: alternatives to supercritical carbon dioxide (SC-CO2), integration of the extract cleanup step, and coupling reaction chemistry in supercritical fluid media to make derivatives for chemical analysis. Alternative fluids that are finding utility include fluoroform, which has a low propensity to coextract fat, new Freons, and multi-phasic systems which enhance the extraction of analytes from complex sample matrices. A special note is made of the potential future role of water as a complimentary extraction to CO2 and the need to employ this moiety in its subcritical state. Sample cleanup using critical fluids is afforded by employing selective sorbents, a novel mode called "inverse" SFE, and binary gas mixtures consisting of CO2 and nitrogen. Derivatization of analytes after extraction from the sample matrix is demonstrated for several specific cases and shown to be of unique advantage in applying SFE for nutritional fat analysis. Other techniques, such as enzyme immunoassay (EIA) and solid-phase micro fibre extraction (SPME), can be employed with SFE to minimize solvent usage in the laboratory or for on-site analysis. Finally, specific cases are cited that demonstrate that SFE has transcended from a research and development tool to everyday use by the food analyst for toxicant, nutrient, and contaminant detection in foods.