Multicore Magnetic Nanoparticles Coated with Oligomeric Micelles: Characterization and Potential for the Extraction of Contaminants over a Wide Polarity Range.

Oligomeric micelles from sodium undecylenate (oSUD) were chemisorbed to magnetic iron oxide nanoparticles (MNPs) through a single-step synthetic route involving the simultaneous nanoparticle formation and functionalization in an aqueous medium. The resulting spherical nanoparticles (MNPs-oSUD) consisted of a concatenation of iron oxides cores, with an average size of 7.7 nm, bound by oSUD micelles (particle average diameter ca. 200 nm). Micellar coverage was around 50% by weight of the MNP-oSUD and offered multiple retention mechanisms (e.g. dispersion, hydrogen bonding, polar and ionic) for solute solubilization while keeping it intact during analyte elution. The high density of micelles and variety of interactions provided by this sorbent rendered it highly efficient for the extraction of aromatic amines in a wide polarity range (log Kow from -0.80 to 4.05) from textiles, urine and wastewater. Extraction took 5 min, no cleanup or evaporation of the extracts was needed and the method, based on LC-MS/MS quantitation, proved matrix-independent. Recoveries for 17 aromatic amines in samples were in the range 93-123% while those with negative log Kow values were in the range 69-87%. Detection limits for aromatic amines in textiles (0.007-2 mg kg-1) were well below the EU legislated limits (30 mg kg-1) and those in urine and wastewater (0.004-1.5 µg L-1) were at the level usually found in real-world. All the analyzed samples were positive in aromatic amines. The easy synthesis and excellent extraction properties of MNPs-oSUD anticipate their high potential not only for multiresidue analysis but also in other fields such as water remediation.