Sizing and simultaneous quantification of nanoscale titanium dioxide and a dissolved titanium form by single particle inductively coupled plasma mass spectrometry

Abstract

As a consequence of their widespread use, titanium dioxide nanoparticles (TiO2NPs) have been released into the environment where they can act as stressors towards biota. For the assessment of the environmental impact of these NPs it is important to quantitatively determine their concentration, size distribution and the dissolved Ti fraction in different water samples. In the present work, a new analytical approach was applied for sizing and quantitative determination of TiO2NPs (anatase and rutile) and dissolved Ti in aqueous samples by the use of single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). The accuracy of the quantification of TiO2NPs by SP-ICP-MS was verified by calculating the recoveries between the determined and expected Ti concentrations (90–100%). The size distributions of TiO2NPs calculated by SP-ICP-MS (108±10nm for rutile, 29±2nm for anatase) were in a good agreement with data obtained by TEM (96–106nm for rutile, 21–38nm for anatase) and DLS (117±22nm for rutile, 42±30nm for anatase). The influence of different dwell times on the sizing and quantification of nanoscale titanium dioxide was also examined. Low limits of detection for NP diameter (37nm) and NP concentration (3.69×10−3ngTimL−1 for rutile and 0.058×10−3ngTimL−1 for anatase) were obtained. In order to apply the procedure developed for the sizing and quantification of TiO2NPs in environmental waters, the severe Ca isobaric interference at m/z 48 was overcome by measuring the Ti on m/z 47. It was demonstrated that the procedure optimized for the determination of Ti in environmental waters can be applied in the sizing and quantification of TiO2NPs in river water samples spiked with nanoscale anatase and rutile.