Phosphoric acid functionalized magnetic sorbents for selective enrichment of TiO2 nanoparticles in surface water followed by inductively coupled plasma mass spectrometry detection

Phosphoric add functionalized superparamagnetic iron oxide was synthesized, and different adsorption behavior of TiO2 NPs and titanium ions on it was found. By means of dispersion -corrected density functional theory (DFTD), the adsorption mechanism of TiO2 NPs and titanium ions on the functionalized sorbents was explored, and the difference in the adsorption behavior was attributed to the different deprotonated forms of phosphates and the competitive adsorption of OW anion with respect to either TiO2 NPs or aqueous titanium ions. Based on the different adsorption performance of phosphoric acid functionalized sorbents for TiO2 NPs and titanium ions under pH 3, a method by combining magnetic solid phase extraction (MSPE) with inductively coupled plasma mass spectrometry (ICP-MS) was established for the selective quantification of trace TiO2 NPs in environmental water. Under the optimal experimental conditions, the detection limit of TiO2 NPs was 17 ng, L with an enrichment factor of 400. The developed MSPE-ICPMS method was applied to the detection of trace TiO2 NPs in the Yangtze River and the East Like water. Sub pg/L level of TiO2 NPs was found in the tested water samples, and recoveries of 91-110% and 90-110% were obtained for TiO2 NPs at three concentration levels in spiked water samples, respectively. The developed method exhibited high adsorption capacity and low detection limit for target TiO2 NPs, and was demonstrated with great potential for monitoring TiO2 NPs in the environment. (C) 2018 Elsevier B.V. All rights reserved.