Liquid phase microextraction integrated into a microchip device for the extraction of fluoroquinolones from urine samples

For the first time, liquid phase microextraction miniaturized into a microfluidic chip device (μLPME) combined with a HPLC procedure using diode array (DAD) has been developed for the determination of four fluoroquinolones: marbofloxacin (MRB), norfloxacin (NRF), ciprofloxacin (CPR) and danofloxacin (DNF). The microfluidic chip consisted of two symmetrical channels which contained the acceptor and sample solution separated by a flat polypropylene membrane. Also, a comprehensive study was carried out in order to determine the importance of geometry optimization in microchips based liquid phase microextraction. The optimal channel size was 23 mm length, 3 mm width and 60 μm depth. Both solutions were delivered to the chip using two syringe pumps and the extract collected was directly analyzed by HPLC. The extractions were carried out under double-flow conditions and completed after 7 min. The procedure was successfully applied to urine samples obtaining recoveries within the range of 35 and 62% for all compounds and 10 μL sample consumption. This miniaturized μLPME-chip device significantly reduced the analysis time and the sample consumption compared to the existing sample preparation techniques for fluoroquinolones.