Analytical Methods

A procedure to determine the presence of nano- or micro- TiO₂ particles in commercial cosmetic formulations, which may have a daily use, is proposed. Two identification techniques the Square Wave Voltammetry (SWV) and ICP-AES were employed to determine the amount of TiO₂ in six foundation creams sold in Italy and the USA. A new SWV method, based on an acidic microwave-assisted digestion of the sample, has been set up and the results were compared and critically commented with those obtained by the established ICP-AES method. The analytical procedure was verified by analyzing the P-25 Degussa sample. The sizes of the particles contained in the foundations were investigated through Sedimentation (SdFFF) and Flow Field-Flow Fractionation (FlFFF) by analyzing aqueous slurries obtained from the foundation through a solvent extraction procedure. The FFF techniques synergically coupled with the ICP-AES made it possible to assess the sizes of the TiO₂ particles. The content of the extracted slurries was also checked by TEM observation.