Identification and quantification of titanium nanoparticles in surface water: A case study in Lake Taihu, China

Abstract The accurate detection and quantification of nanoparticles ( NPs) in aquatic environments are essential for toxicological and ecological risk assessment. Herein, we used single particle inductively coupled mass spectroscopy (SP-ICP-MS) to quantify titanium nanoparticles (Ti- NPs) in the extraction fractions of surface waters, and transmission electron microscopy coupled with an energy dispersive X-ray spectrometer (TEM-EDS) to specifically identify the nanoparticles. By using gold- NPsas reference standard, this approach achieved a Ti- NPssize detection limit in water of 25 nm with a particle numberconcentration limit of 102 particles/ml. We measured Ti- NPsconcentrations in surface watersfrom Lake Taihu, China. The results revealed that the particles concentration was 2.78 × 105 particles/ml with the mean size of 67 nm in October 2016, and the particles concentration of 2.28 × 105 particles/ml with the mean size of 65 nm in April 2018, respectively. Based on TEM-EDS observation, various shapes of Ti- NPswere further identified, including regular cubes, long rods and flaky. We further measured the total organic carbon(TOC), and found that there was a positive correlation between Ti- NPsand TOC. This method enabled accurate detection and quantification of Ti- NPsconcentration in environmental surface waters, which could be hugely useful for environmental risk assessment in aquatic systems.