Deep eutectic solvent - loaded Fe3O4@MIL-101(Cr) with core–shell structure for the magnetic solid phase extraction of non-steroidal anti-inflammatory drugs in environmental water samples

A novel deep eutectic solvent - loaded magnetic solid phase extraction (DES-L-MSPE) method was proposed, which was based on the direct loading of a hydrophobic DES composed of L-menthol and lactic acid (1:2) into the pores of core–shell magnetic Fe3O4@MIL-101(Cr) nanoparticles. The function of DES was to condition the Fe3O4@MIL-101(Cr) and promote liquid phase microextraction for the analytes. Through coupling with HPLC-UV analysis, this method was utilized for the determination of six non-steroidal anti-inflammatory drugs (NSAIDs), including ketoprofen, naproxen, flurbiprofen, diclofenac sodium, ibuprofen, and mefenamic acid in environmental water samples. The influencing parameters such as type and ratio of DES, amount of adsorbent, sample solution pH, salt concentration, extraction time, elution solvent and time were investigated and optimized in detail. Under the optimal conditions, the method exhibited good linearity (5.0–1000 μg/L for ketoprofen, ibuprofen, 1.5–600 μg/L for flurbiprofen, mefenamic acid, 2.5–1000 μg/L for naproxen and 3.0–600 μg/L for diclofenac sodium with the correlation coefficients ranging from 0.9972 to 0.9993), low limits of detection (0.20–1.1 μg/L), and high precision (RSD < 8.2 %). Besides, the recoveries in spiked lake and river water samples were 89.8 %–110.4 % and 83.8 %–109.0 %, respectively. Taken together, the established method was proved to be simple, fast, highly sensitive and accurate for the determination of NSAIDs from aqueous matrices.