The mixture of supercritical CO2 and co-
solvent passed through the extraction cell, where the extraction
took place. A thermo-resistance maintained the desired tempera-
ture, which was measured in the internal flow before and after the
vessel. After extraction, the mixture of solvents was expanded by
a medium-flow high-pressure metering valve inserted in a water
bath at 40 ◦C to avoid CO2 freezing caused by sudden expansion.
CO2 gas at atmospheric temperature passed through a flow meter
before being vented. The extract and the co-solvent were collected
in 20 mL of ethanol and they were afterwards separated by rotary
evaporation. All experimental runs were carried out in duplicate.
The average and the standard deviation were calculated on the base
of the two measures.