Deep Eutectic Solvent Functionalized Graphene Oxide Based Ferrofluid for the Liquid Phase Microextraction of Fluoroquinolones from Water Samples

The development of smart materials have a significant impact on sample preparation and preconcentration methods. Ferrofluid or magnetic fluids (FF) are smart colloidal suspensions of single domain magnetic nanoparticles in a polar or non-polar liquid carrier. In this study, graphene oxide magnetite (GO@Fe3O4) and deep eutectic solvent-based choline chloride and ethylene glycol as a carrier liquid were utilized to form GO@Fe3O4-DES FF. The synthesised GO@Fe3O4-DES FF was characterized using FTIR, SEM, TEM and vibrating sample magnetometer (VSM). GO@Fe3O4-DES FF was further developed for the application of GO@Fe3O4-DES FF-liquid phase microextraction (LPME) for enrofloxacin as test compound. Several parameters such as type of FF composition and volume, extraction time, desorption solvent volume, desorption time and solution pH were optimised and analysed using HPLC-UV. Under optimum conditions, the developed GO@Fe3O4-DES FF-LPME method showed good linearity, R2 ≥ 0.9921, repeatability, RSD 0.57 – 9.40 %. The developed GO@Fe3O4-DES FF-LPME method was applied for the determination of enrofloxacin in water samples from Langat River Basin, Selangor and the recovery of 71.6 – 112.3% was obtained. In conclusion, the developed GO@Fe3O4-DES FF-LPME method for the determination of enrofloxacin showed excellent sensitivity and precision and may be an excellent alternative method for the extraction on water samples.