Electromembrane extraction was performed using equipment based on conductive vials to house the sample and acceptor solution, provided by Extraction Technologies Norway (Ski, Norway). The equipment is illustrated in Figure . Unless otherwise stated, conductive vials with a total inner volume of 600 µL and a working volume of 200-500 µL were used. For EME, a pair of vials -one for the sample and another for the acceptor-were fastened into a custom-designed Teflon union that housed the supporting membrane infused with the liquid membrane, together forming a single extraction cell. The 9 mm diameter supporting membrane comprised polypropylene (PP2E, Extraction Technologies Norway). In this configuration, the conductive vials thus served as the anode and cathode. Up to 10 extraction cells were loaded into a 10-position holder mounted on a horizontal shaker (Extraction Technologies Norway) and covered by a lid with one printed electrode for each vial. The lid was connected to a power supply (model ES 0300-0.45, Delta Elektronika BV Zierkizee, Netherlands) and a multimeter (Fluke287, Everett, WA, USA) to monitor the current during extraction.