Preparation of Fe3O4@PPy magnetic nanoparticles as solid-phase extraction sorbents for preconcentration and separation of phthalic acid esters in water by gas chromatography–mass spectrometry

• We introduce a micro-solid phase extraction method of separating and determining of phthalic acid esters (PAEs).
• PPy-coated Fe3O4 magnetic nanoparticles (Fe3O4@PPy MNPs) which was uniformly wrapped and distributed in matrices were served as sorbents.
• Orthogonal experimental design was applied to investigate the optimum extraction conditions through the least experiments.
• The applicability of the developed method for the determination of PAEs in real water sample was confirmed.

The purpose of this paper is to introduce a solid-phase extraction method of separating and determining of phthalic acid esters (PAEs) by PPy-coated Fe3O4 magnetic nanoparticles (Fe3O4@PPy MNPs). In the process, nanoparticles were served as sorbents and the optimal conditions of the extraction have been explored. The composite was synthesized through the chemical oxidation method, combining pyrrole monomer with Fe3O4 magnetic ball in the form of aggregation state and the coated nanoparticles possessed core–shell construction. The PPy-coated Fe3O4 magnetic microspheres have been extensively characterized by transmission electron microscopy, Fourier transform infrared spectroscopy and vibrating sample magnetometry. The optimum conditions were investigated by orthogonal experimental design, which was used to testing the influence of main factors and the interactions among them. The orthoplan is famous for the merit that it can study the whole experiments comprehensively through minimal tests. Under the optimal extraction conditions: 20 mg of modified magnetite nanoparticles, eluting with acetic ester of 2 mL, 40 min of MSPE, eluting in 1 h and 20 mL of sample volume, good linearity (r2 > 0.9912) of all calibration curves was obtained in validation experiments. And the limits of detection (LODs) were from 0.006 to 0.021 ng/mL. The recoveries in different sample matrices were in the range from 80.4% to 108.2% with relative standard deviations less than 12.8%. The present work demonstrates the applicability of the developed method for the determination of PAEs in water sample and the results justified that it can be applied successfully to the selective isolation and enrichment of PAEs in real water samples.