Four grams of alperujo were placed in an extraction chamber, which was assembled and filled with the leaching carrier impelled by a peristaltic pump. After filling, the extraction chamber was immersed into a water bath at room temperature, maintained during the extraction time. The leaching carrier (methanol - water (1:3, v/v)) was then circulated through the solid sample for 13 min preset time under ultrasonic irradiation. During extraction, the direction of the leaching carrier (at 2 mL/min flow rate) was changed each 40 s, thus minimising both dilution of the extract and increased compactness of the sample in the extraction cell that could cause overpressure in the system. After extraction was complete, the extract (6 mL) was collected.

Column conditioning: The columns were washed with 3 mL methanol and 3 mL water.

Sample aspiration: 6 mL sample were passed through the column.

Column washing: The column was rinsed with 3 mL water.

Elution: 3 mL methanol.