A Triple Functional Approach To Simultaneously Determine the Type, Concentration, and Size of Titanium Dioxide...

The large-scale manufacturing and use of titanium dioxide (TiO₂) particles in food and consumer products significantly increase the likelihood of human exposure and release into the environment. We present a simple and innovative approach to rapidly identify the type (anatase or rutile), as well as to estimate, the size and concentration of TiO₂ particles using Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS). The identification and discrimination of rutile and anatase were based on their intrinsic Raman signatures. The concentration of the TiO₂ particles was determined based on Raman peak intensity. Particle sizes were estimated based on the ratio between the Raman intensity of TiO₂ and the SERS intensity of myricetin bound to the nanoparticles (NPs), which was proven to be independent of TiO₂ nanoparticle concentrations. The ratio that was calculated from the 100 nm particles was used as a cutoff value when estimating the presence of nanosized particles within a mixture. We also demonstrated the practical use of this approach when determining the type, concentration, and size of E171: a mixture that contains TiO₂ particles of various sizes which are commonly used in many food products as food additives. The presence of TiO₂ anatase NPs in E171 was confirmed using the developed approach and was validated by transmission electron micrographs. TiO₂ presence in pond water was also demonstrated to be an analytical capability of this method. Our approach shows great promise for the rapid screening of nanosized rutile and anatase TiO₂ particles in complex matrixes. This approach will strongly improve the measurement of TiO₂ quality during production, as well as the survey capacity and risk assessment of TiO₂ NPs in food, consumer goods, and environmental samples.