Effects of Fe3O4 Magnetic Nanoparticle Functionalization with Ionic Liquids and a Double-Chained Surfactant on the Pretreatment of Plasma Samples during Drug Extraction

Ionic liquids (ILs), also known as “designer solvents,” comprise a large group of compounds that can improve overall sample preparation performance due to their unique physical and chemical properties. Some of them have a comparable structure to surfactants, which can be also considered as effective extraction solvents. In this study, nine different ILs and a double-chained surfactant were investigated as potential coating materials for iron oxide-based nanoparticles (NPs) used in the pretreatment of human plasma samples. Various methods of synthesizing and functionalizing NPs were employed in fabricating the magnetic sorbents, with the physicochemical properties of the resultant extraction phases (i.e., naked NPs, NPs coated with silica, and NPs coated with silica and selected IL or surfactant) being characterized via X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TG), and transmission electron microscopy (TEM). The effectiveness of the developed NP-based extraction phases was tested by applying them for the extraction of epirubicin hydrochloride (EPI) from plasma samples, followed by analysis via liquid chromatography with fluorescence detection (LC-FL). The results showed that NPs coated with both silica and IL or silica and surfactant provided significantly higher extraction efficiency compared to naked NPs and NPs coated solely with silica. Additionally, the findings also revealed that the adsorption of analytes depends not only on the coating procedure but also on the type of coating material used to functionalize the NPs. Among the tested structures, didodecyldimethylammonium bromide provided the best performance for the functionalization of NP sorbents previously coated with silica.