Prospects of surfactant assisted dispersive liquid–liquid microextraction for the selective extraction of silver and titanium dioxide nanoparticles from tap water and determination by spICP-MS

Abstract

The widespread use of inorganic nanoparticles (NPs), especially silver (Ag) and titanium dioxide (TiO₂) NPs, has led to growing concern about their impact on human health and the environment. Inorganic nanoparticles are present in a large variety of products including cosmetics, foodstuffs, and medical goods, and NPs releasing from consumers' products into the environment can be therefore expected. Because of the low concentration levels of NPs in water, special care must be taken when developing new reliable analytical methods. In the current research, the possibilities of surfactant-assisted dispersive liquid–liquid microextraction (SADLLME) in combination with single-particle inductively coupled plasma mass spectrometry (spICP-MS) have been explored/discussed. Optimum conditions for the pre-concentration of TiO₂ NPs and Ag NPs were 10 mL of water sample, 1.0 mL of the Triton X114/1,2-dichloroethane (49 : 1) mixture, vortexing at 1500 rpm for 30 s, and centrifugation at 3500 rpm for 5 min. The collected organic phase was finally diluted to 1–2 mL with 1% (w/v) glycerol, leading to an enrichment factor within the 5–10 range. The developed procedure (sample pre-treatment and spICP-MS) led to a size detection limit (5σ criteria) of 65.8 and 16.7 nm for TiO₂ NPs and Ag NPs, respectively. The limit of detection in number concentration was 6.06 × 10⁶ L⁻¹ for Ag NPs and 2.85 × 10⁶ L⁻¹ for TiO₂ NPs, whereas the limit of detection for dissolved Ag and Ti mass concentrations was found to be 0.435 and 9.82 ng L⁻¹, respectively. The operational simplicity, low cost and less consumption of organic solvents make SADLLME a greener and faster choice compared to classical liquid–liquid extraction techniques.