Highly selective capture and efficient concentration of trace titanium dioxide nanoparticles in environmental waters by phosphorylated ferroferric oxide

Abstract

Selectively and efficiently capturing trace titanium dioxide nanoparticles (TiO₂NPs) in environmental waters is a prerequisite for their determination to understand their occurrence, behavior and effects in the environment. Herein, we report the determination of TiO₂NPs by using magnetic microextraction with phosphorylated Fe₃O₄ as a selective adsorbent, followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. The phosphorylated Fe₃O₄ was prepared by modifying phosphoric acid groups on the surface of synthesized Fe₃O₄, added into the water samples to selectively adsorb and agglomerate with TiO₂NPs, and collected using a permanent magnet. Under the optimized extraction parameters, the factors including sizes and concentrations of TiO₂NPs, volumes of water samples, and dissolved organic matter (0–30 mg C L⁻¹) showed little effects on the extraction process. The feasibility of the method was further validated by the analysis of natural water samples, with spiked recoveries of 81.9–99.1% and an extremely low detection limit of 0.4 ng L⁻¹. This method is capable of accurately detecting and quantifying the concentration of trace TiO₂NPs in aquatic systems, which contributes to monitoring the fate of TiO₂NPs in the environment and assessing their hazards.