Electromembrane extraction of basic pharmaceuticals from biological matrices using a micro-pillar stabilized liquid membrane

In this work, a reusable microfluidic device for electromembrane extraction (EME) was fabricated from stoichiometric thiol-ene and evaluated for the extraction of a large set of pharmaceuticals across a broad polarity range and from urine and saliva samples. The device featured micro-pillar arrays for stabilization and straightforward renewal of the liquid membrane, enabling repeated use of the same microchip. The thiol-ene material provided a suitable balance of hydrophobic and hydrophilic properties, allowing controlled handling of both aqueous solutions and organic liquid membranes. Extractions were performed at sample and acceptor flow rates of 2.0 µL/min, an extraction potential of 2.0 V, and an extraction time of 10 minutes, using liquid membranes of different polarity. In total, the system was evaluated for the extraction of 61 basic pharmaceuticals covering log P values from -0.5 to 5.0 in water, urine, and saliva. Depending on membrane and matrix composition, typical recoveries were around 40%, while stable operation was observed with all three matrices. The method showed favorable greenness, with low power consumption and minimal waste generation. The thiol-ene microchip has a mass of 16 g and was reused for multiple extractions, while only 0.1 µL of liquid membrane was discarded per extraction, corresponding to more than 99.9% material reuse. Overall, this system provided a sustainable, reusable, and versatile microfluidic platform for EME of pharmaceuticals from biological fluids.