Submitted to: Supercritical Fluids International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/1996
Publication Date: N/A
Technical Abstract: Extractions and chromatography in the supercritical fluid state have been a subject of some controversy among investigators. We report our experiences in blending high pressure gases with organic solvents, above and below the Tc and Pc, to enhance recovery and to control retention of target analytes with these hybrid solvents for extraction and chromatography. Experiments performed on non-polar polymeric-based stationary phases have shown the necessity for large modifier concentrations to moderate excessive retention while providing good separation and recovery of target analytes. Neither SC-CO2 nor organic modifiers appreciably swell these highly cross-linked resins, so the retention mechanism is predominately one of adsorption. Separation of pesticides from lipid interferences is but one example of the use of these hybrid solvent systems, and the chromatography can be performed on relatively simple and inexpensive systems. SC-CO2 modified with organic solvents has proven useful for the extraction of polar analytes from agricultural and food matrices. SFE of aflatoxins B1 and M1 from corn and beef liver, respectively, have been reported. SC-CO2 (at 68 MPa) with 15 mole% EtOH is critical for high recovery of phospholipids from soy meal. This means that modified SC-CO2 at lower extraction pressures is not always able to yield high analyte recoveries, and higher pressures abetted by cosolvent may be required.