A modified zeolite/iron oxide composite as a sorbent for magnetic dispersive solid-phase extraction for the preconcentration of nonsteroidal anti-inflammatory drugs in water and urine samples

This study is the first to use a new ZSM-5 zeolite-based composite decorated with iron oxide magnetic nanoparticles and modified with hexadecyltrimethylammonium bromide surfactant (i.e., HDTMA-ZSM-5/Fe2O3) as an efficient sorbent for magnetic dispersive solid-phase extraction (MDSPE) of nonsteroidal anti-inflammatory drugs in water and urine samples with subsequent measurement by liquid chromatography diode array detection. Experimental factors affecting MDSPE were optimized using a multivariate optimization strategy. The optimum experimental conditions were: amount of sorbent, 40 mg; sample pH, 2.2; NaCl concentration, 2.5%; extraction time, 2 min; eluent solvent, methanol; eluent solvent volume, 424 μL; and elution time, 2 min. The linearity of the method was studied from 3.3 to 400 μg L−1 (N = 8) for ketoprofen, from 1.7 to 400 μg L−1 (N = 8) for felbinac, from 6.6 to 400 μg L−1 (N = 7) for diclofenac and from 9.9 to 400 μg L−1 (N = 6) for ibuprofen. Method repeatability was evaluated at 10 and 200 μg L−1 spiking levels, obtaining coefficients of variation between 2 and 5% (n = 6). Limits of detection, determined empirically, were 1.0 μg L−1 , 0.5 μg L−1, 2.0 μg L−1 and 3.0 μg L−1 for ketoprofen, felbinac, diclofenac and ibuprofen, respectively. Tap water, reservoir water, wastewater and five urine samples were selected to assess method applicability. Recovery values ranged between 86–107% and 80–112% for water and urine samples, respectively, showing negligible matrix effects. Finally, this method was employed to monitor ibuprofen excretion in real urine samples.The authors would like to thank the Spanish Ministry of Economy and Competitiveness and European Union (FEDER funds) (project n. CTQ2016-79991-R) for the financial support. P. Baile also thanks Ministry of Education, Culture and Sports for her FPU grant (FPU14/04589)