In-line and off-line trapping of lipids extracted from chicken liver by supercritical carbon dioxide

This supercritical fluid extraction study determined the retentive properties of neutral alumina sorbent as an in‐line trap for lipids in the dynamic state over a pressure range of 490–680 bar and temperatures of 40 and 80°C. Lipids were extracted from a chicken liver matrix using supercritical carbon dioxide over a 40‐min period at a flow rate of 3 L/min (expanded gas), then were quantified by high‐performance liquid chromatography using an evaporative light‐scattering detector. Approximately 30 and 18%, respectively, of the total extracted lipids were trapped on the in‐line alumina sorbent bed at 40°C as the operating pressure increased from 490 to 680 bar, while the remaining lipids were trapped off‐line after CO2 decompression. The major lipid classes trapped in‐line were fatty acids and cholesterol, whereas only minor amounts of the less polar lipid classes such as sterol esters and triacylglycerols were retained. At 80°C and 680 bar, less than 1.5% of the extracted total lipids was trapped in‐line, indicating the lack of adsorptive selectivity for lipids by alumina under these conditions.