Jerry W. King

Supercritical Fluid—Adsorbate—Adsorbent Systems: Characterization and Utilization in Vegetable Oil Extraction Studies

Supercritical fluid (SCF) extraction of vegetable oils from a seed matrix may require the incorporation of an adsorbent bed to remove odoriferous compounds from the recycle gas stream. In this study, an elution pulse chromatographic technique has been developed which allows the determination of breakthrough volumes (BTV) for an array of odor-causing sorbates on Tenax-TA, KAD resins, and activated carbon adsorbents. Data taken over a 100-400 atmosphere range at three different temperatures indicate that the adsorbent retention capacity is rapidly lost at pressures beyond 200 atmospheres. In specific cases with the synthetic polymer sorbents, the supercritical carbon dioxide changes the sorption capacity of the resin phase by altering the physical morphology of the sorbent. Differential heat of adsorption measurements suggest that modification of the gas-solid interface by the supercritical fluid is enhancing migration of the sorbates through the column bed. Calculations incorporating the derived BTV data base illustrate how conditions can be altered to improve trapping efficiency by varying the fluid pressure, temperature, flow rate, and sorbent charge.

Supercritical Fluid Extraction of Aflatoxin M1 from Beef Livert

Supercritical fluid extraction (SFE) and a pressurized-fluid-extraction process were applied for the removal of aflatoxin M1 from beef liver samples. Various pressures, temperatures, quantity of supercritical carbon dioxide, and organic modifiers were investigated to optimize the extraction methods. Organic modifier was found to be essential for quantitative recovery of aflatoxin M1. Extracts were cleaned up by solid-phase extraction and were analyzed via high-performance liquid chromatography coupled with fluorescence detection of the trifluoroacetic acid derivative. Solvent-modified carbon dioxide SFE achieved recoveries comparable to an AOAC-approved method involving organic solvent extraction. SFE allowed the traditional amounts of sample and organic solvent to be reduced. Also, the supercritical-fluid extraction permitted the use of carbon dioxide modified with acetonitrile: methanol (2:1) to replace methylene chloride as the organic solvent for the extraction step.