Analytical nanometrological approach for screening and confirmation of titanium dioxide nano/micro-particles in sugary samples based on Raman spectroscopy - Capillary electrophoresis.

Analytical nanometrology is a present challenge in today's analytical science, particularly from a practical point of view and when it is addressed to routine/control laboratories. In this way, a screening-confirmation approach is described for the characterization and distinction between titanium dioxide nano/micro-particles in sugary food samples. The first step involves the confirmation of the presence of TiO in the sample (used as additive E171 in sugary samples), using a portable Raman spectrometer, in which the crystalline structure of TiO (anatase or rutile) in the positive samples can be also obtained in this step. Then, the second step was only applied to positive samples, and it involves the use of Capillary Electrophoresis (CE), which allows to distinguish between TiO-nanoparticles (<100 nm) from TiO-microparticles (>100 nm). Additionally, nanoparticles (TiO anatase (5 nm diameter) and TiO rutile (60 nm diameter) and rutile microparticles (0.1-0.2 μm diameter) can be electrophoretically separated. The general procedure is simple, fast, and low cost, providing a valuable analytical tool in the field of food safety and control, thus contributing to the development of the analytical nanometrology.