Preparation of magnetic iron oxide nanoparticles modified with imidazolium-based ionic liquids as a sorbent for the extraction of eight phthalate acid esters in water samples followed by UPLC-MS/MS analysis: an experimental design methodology

Abstract

In the present study, different ionic liquid modified magnetic nanoparticles have been prepared and tested as nano-metric adsorbents for the analysis of eight phthalic acid esters (PAEs) from water samples using dispersive micro solid-phase extraction (D-micro-SPE). Determination and identification of the PAEs were performed by ultra performance liquid chromatography-tandem mass spectrometry. Compared with ionic liquid functionalized magnetic nanoparticle adsorbents, benzimidazolium-chloride modified iron oxide nanoparticles (Fe₃O₄@[Bimi]Cl NPs) show higher extraction efficiency for all PAEs. The Fe₃O₄@[Bimi]Cl NPs were fully characterized by Fourier-transform infrared spectroscopy, field emission-scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and zeta potential analysis. The D-micro-SPE conditions, including sample pH, adsorbent dosage, extraction time, type of desorption solvent, volume of elution solvent, and desorption time, were optimized using both univariate and multivariate techniques based on response surface methodology. Under optimized conditions, the developed method was validated for PAE analysis in different water samples, including river water, tap water, bottled mineral water, well water, and wastewater. The method features wide linearity and low limits of detection ranging from 0.002–0.012 μg L⁻¹. In addition, recoveries ranging from 83% to 111% with a precision (RSDs) of lower than 8% were obtained. Therefore, the proposed method is an efficient pretreatment procedure and can be utilized for the sensitive determination of PAEs in different water samples.