LAUSR

A switchable hydrophilicity solvent membrane-based microextraction (SHS-MME) strategy for simple and highly-available sample pretreatment of complex matrices has been proposed. The SHS-MME procedure based on extraction of target analytes from an aqueous sample into a porous hydrophobic membrane impregnated with a switchable hydrophilicity solvent (SHS) followed by SHS ionization and back-extraction of the analytes in alkaline acceptor solution. The medium-chain fatty acids were investigated as SHS for the SHS-MME of fluoroquinolones (fleroxacin, lomefloxacin, norfloxacin and ofloxacin). The SHS-MME was successfully coupled with a HPLC-FLD for the determination of fluoroquinolones in shrimp samples with no further sample pretreatment. The calibration graphs were linear over the concentration ranges of 3-1500 μg L-1 for ofloxacin, 10-1000 μg L-1 for norfloxacin, 15-1500 μg L-1 for lomefloxacin and fleroxacin. The limits of detection, calculated from a blank test based on 3σ, were 1 μg L-1 for ofloxacin, 3 μg L-1 for norfloxacin and 5 μg L-1 for lomefloxacin and fleroxacin. The SHS ionization can be considered as new potential fields in analytical application of membrane-based liquid phase microextraction.