Effect of Sample Matrix Dehydration During Supercritical Fluid Extraction on the Recoveries of Drug Residues from Fortified Chicken Liver

The role of H2O in the supercritical fluid extraction (SFE) of zoalene (3,5-dinitro-o-toluamide) and its metabolites from fortified chicken livers is reported. Dehydration of the sample matrix during SFE results in adsorption of the analytes, limiting their extraction. Adding 0.5 mL of additional water to the sample matrix prior to SFE prolongs the effective extraction period, thereby increasing the recoveries of the metabolites 12–20%. The following recoveries are found for zoalene, 3-amino-5-nitro-o-toluamide, 5-amino-3-nitro-o-toluamide, and N5-acetyl-3-nitro-o-toluamide extracted from a liver-Na2SO4 mixture with added H2O at 60°C and 1034 bar (density, 1.069) using 3 L CO2/min (expanded gas) for 30 min: 87, 92, 77, and 66%, respectively.